Scientific and technological advances from DCNS_no. 2

Transcription

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RESEARCH
Scientific and technological advances from DCNS_no. 2
CONTENTS
04_ EDITORIAL
06_ FOREWORD
08_ NEWS
11_ PERFORMANCE AT SEA
AND MARINE PLATFORM DYNAMICS
Virtual Ship: integrated
ship design in the preliminary project phase
MAX: generic autonomous model
for submarine manoeuvrability studies
17_THROUGH LIFE RESISTANC
Modelling of mechanical propulsion transmissions
Composite material antenna systems
Multifunctional composite materials for
military naval applications
COVER ILLUSTRATION: computer-generated
image representing fibre optics.
25_ENERGY OPTIMISATION
Optimised operation of ships: simulations and optimisations
29_ONBOARD INTELLIGENCE
Architecture of a guidance system for autonomous vehicles
33_INFORMATION MANAGEMENT
New data association processing solutions
Tracking manoeuvring targets in 3D
Innovation and human factors
43_STEALTH AND ANTENNA INTEGRATION
Vibroacoustic radiation by plates in transient states
47_PRODUCTIVITY AND COMPETITIVENESS
OF INDUSTRIAL PROCESSES
Evaluation of friction stir welding (FSW) on high yield
strength steels for shipbuilding
The development of TOFD at DCNS
Biofilms and corrosion of corrosion-resistant alloys in sea water
Digital engineering and future shipyard
60_OUR SCIENTIFIC PUBLICATIONS
RESEARCH_2. The DCNS scientific and technological review. Executive editor: Gilles LANGLOIS _Editorial board:
Christian AUDOLY, Julien BÉNABÈS, Alexia BONNIFET, Luc BORDIER, Marc BOUSSEAU, Jean-Michel CORRIEU, François CORTIAL, Xavier DAL
SANTO, Sylvain FAURE (CEA), Fabien GAUGAIN, Anne-Marie GROLLEAU, Joëlle GUTIERREZ, Emmanuel HERMS (CEA), Guillaume
JACQUENOT, Dann LANEUVILLE, Cédric LEBLOND, Jean-Jacques MAISONNEUVE, Thierry MILLOT, Pol MULLER, Adrien NEGRE, Antoine
PAGÈS, Fabian PÉCOT, Mathieu PRISER, Ygaal RENOU, Lucie ROULEAU, Céline ROUSSET, David ROUXEL, Florent SAINCLAIR, David-François
SAINT-CYR, Jean-François SIGRIST, Camille YVIN _Design and production:
_Photo credits: DCNS – all rights reserved.
RESEARCH_2
03
EDITORIAL
“The acceleration of worldwide
competition both in shipbuilding
and in the marine renewable energy sector
necessitates the development
of new design and production methods.”
Gilles Langlois, head of DCNS Research
DCNS Research is one of the growth drivers of the
also regularly produce innovative test protocols for the
Group. Its contribution will enable us to take up the
aerospace industry.
boldest challenges in shipbuilding, energy and the
sustainable development of the oceans.
To speed up the international development of DCNS,
DCNS Research practises innovation in all its forms:
DCNS Research brings together internationally-reputed
1 • technological: we invite you to read about some
researchers, experts with experience of complex pro-
examples i n issue no. 2 of the DCNS RESEARCH
grammes and engineers eager to identify the emergent
magazine;
trends with DCNS customers.
2 • marketing: our experts are working continuously
on the market positioning of our innovations;
04
Bringing together areas of excellence as varied as
3 • operating concepts: our teams are working on the
corrosion, materials, acoustics and algorithms, not for-
exploration of new technological building blocks which,
getting hydrodynamics, DCNS Research makes a wide
like drones, will revolutionise military operations and
range of contributions to the DCNS Group: from expert
exploitation of the oceans in the years to come;
assessment on submarines in service to the develop-
4 • process: through open innovation and collaborative
ment of technology for significantly increasing the ope-
research, international partnerships and integration
rational capabilities of the ships produced by DCNS, we
since 2008 of a true SME, SIREHNA®, into the Group.
RESEARCH_2
EDITORIAL
Spearhead of DCNS Group R&T thanks to the com-
The world is accelerating, let’s accelerate!
bination of expertise, research and modelling, DCNS
In conclusion, I want to stress that the application of
Research contributes to the vision and to the deve-
innovations in emerging markets and the development
lopment of the Group. It is a vector of international
of industrial and research partnerships enable us to
growth for the DCNS Group, for example through its
observe that the results and work of DCNS Research
cooperation projects with research centres in France,
lead to competitive advantage, customer satisfaction,
in Europe and around the world.
but also a real career boost for our employees.
DCNS Research is heavily involved in the development
I wish you excellent reading of the second issue of
of a collaborative framework, in particular with the IRT
RESEARCH magazine.
Jules Verne, the IRT SystemX, the “l’Usine du futur”
(future factory plan) research group, competitiveness
clusters such as EMC2 and academic and industrial
partners in all sectors of activity. The research work in
the shipbuilding and marine renewable energy sector
concerns the design and manufacturing processes for
metal structures, and the behaviour of these structures
in the marine environment (resistance to the sea,
shocks, corrosion, etc.).
The research & development and innovation
of the Group gets organised in France
In a few months, the DCNS Research activ ities in
Nantes will be relocated to the Technocampus Océan
(Nantes/Bouguenais). In addition to its fi nancial investment in this project, the Pays de la Loire regional
council is project manager for the architectural project
comprising 16,000 m 2 of offices and laboratory space.
The platform will combine common, office and workshop spaces for collaborative projects and facilities, as
well as private spaces, rented by companies and university researchers. The complex will be a true scientific
showcase, a tremendous vector of the region’s capacity
for innovation. Information-related activities applicable
to embedded systems and to maritime surveillance and
security networks will be relocated to the Technopôle
de la Mer at Ollioules (south-eastern France).
RESEARCH_2
05
FOREWORD
The Océanides project
Claudie Haigneré, President of Universcience
Throughout history, the oceans have always been
innovation amplify the flourishing of ideas and speed up
sou rces of power a nd prosper it y for hu m a n it y.
the emergence of new technologies.
That is what the Océanides project is intended to study
and illustrate. Sponsored by the minister of Ecology,
But there are also considerable human issues. One of
Sustainable Development, Transport and Housing, the
these issues is in education and training. Our world is
Océanides project, a DCNS initiative, is being carried out
changing every day, our time is fi lled with uncertainties
in partnership with some twenty companies, local autho-
and, little by little, some citizens are fi nding themselves
rities, higher education institutions, research institutes
on the margins of this society of knowledge. We must
and professional federations, with active support from
also prepare our young people to master, and tomorrow
the French Cluster Maritime.
invent, this ever-changing technology. How can not only
sound knowledge but also the thirst for understanding,
Sustainable development of the oceans and protection of
the appetite for learning and the enthusiasm for creating
marine resources are today still areas full of promise for
be transmitted to as many as possible?
the future and new opportunities for our industries.
It is now necessary to invent, in society as in compa-
06
However, the growth and the industrial recovery that
nies, new forms of communication, more interactive,
our country needs, in a globalised environment where
more participative and more creative, restore pas-
the most precious resource is knowledge, necessitate an
sion to the professions of industry, give new life to the
increased effort in the areas of research and innovation.
technical sector.
There are scientific and technical issues underlying this
I salute the DCNS initiative to publish the latest results
effort. Industry, public-sector laboratories, universities
of its technological research. Much of this work is being
and other higher education institutions must collaborate
done by brilliant doctoral students. I hope that they
to invent, innovate and develop new concepts, new pro-
contribute to mobilising yet more young people for the
ducts and new services. Collaborative research and open
fi ne professions of the sea.
RESEARCH_2
FOREWORD
RESEARCH_2
07
NEWS
DCNS is developing research
programmes with Dalhousie University
At the end of November 2013, Patrick Boissier announced the signature of
a partnership with Dalhousie University in Halifax for developing bilateral
research programmes.
The MoU (Memorandum of Understanding) defines the general framework for
collaboration programmes for five years. According to Jean-François Sigrist,
manager of the research team at DCNS Research, this MoU represents a nonnegligible competitive advantage for DCNS: “We are going to develop new research
work with Dalhousie University on the ‘dynamics of structures’ (surface ships,
submarines, offshore platforms, etc.) and their behaviour in the marine environment.
We are also planning scientific exchanges between France and Canada, and hosting
of students (master, doctorate).”
These encouraging prospects for DCNS, in the position of challenger in the face
of competition from the United States, echo the announcement by Prime Minister
Harper and President Hollande in June of a roadmap for bilateral cooperation,
covering for example international security and defence. They also contribute to a
climate of strengthened economic partnership following the recent signature of a
free trade agreement between Canada and Europe.
DITCHING TESTS
DCNS Research and SIREHNA® are working together on rigorous ditching tests.
In recent years, the study of the behaviour
of helicopters in the event of ditching at
sea has become essential in the context
of the certification of the floatation and
safety systems fitted to these aircraft.
Ditching tests also provide data that
can only be obtained experimentally, as
full-scale ditching tests are inconceivable.
For the manufacturer and/or the supplier
of floatation systems, the objective is
to validate the dynamic stability of the
helicopter for various float and centre of
gravity configurations and environmental
conditions (sea state and wind), stability
which will enable the crew to evacuate
the helicopter in the event of ditching.
At present, there are two types of sea landing
test: dynamic stability tests, the objective
of which is to validate the seaworthiness of the
helicopter once it has landed in the sea, and
ditching tests proper, the objective of which
is to characterise the sea landing phase. For
these two types of test, the goal is for DCNS
Research/SIREHNA® to supply a complete test
package: specification and production of the
model and the floatation system; balancing;
choice of test facility; running and analysing
the tests.
2013 RESEARCH PROJECTS
Fabien Gaugain
“Experimental analysis and numerical
simulations of fluid-structure
interaction of an elastic hydrofoil in
cavitating and subcavitating flow.”
Doctoral Thesis, École nationale
supérieure d’arts et métiers de Paris,
2010-2013.
Marine Robin
“Validation of a fluid-structure
coupled calculation chain for
dimensioning structures under flow.”
École nationale supérieure de
l’énergie, l’eau et l’environnement,
Grenoble INP, 2013.
Élise Chevallier
“Towards numerical simulation
of fluid-structure interaction in
large displacements.” EnseirbMatméca intership report,
September 2013.
David Louboutin
“Experimental data acquisitions
on DCNS configurations:
comparisons with simulation (civa
and athena) and modelling (mina)
software.” Internship report 2013:
“Ultrasound waves propagation in
austenitic welds”, Institut français de
mécanique appliquée.
Alexandre Rochas
“Feasibility of a seawater pump
impeller made of composite materials
– surface ship application”, Ensiacet
internship report, August 2013.
Lucie Rouleau
“Vibro-acoustic modelling of
sandwich structures with viscoelastic
material layers”. Doctoral thesis,
Conservatoire national des arts
et métiers de Paris, October 2013.
08
RESEARCH_2
NEWS
KEY EVENTS
2013 RESEARCH DAYS
Nantes-Indret (France), 25-26 June 2013.
On 25 June, in partnership with
the Audencia management school
and the consultancy firm Bessé,
more than 220 persons from regional
and national entities involved in
the economy, research and education
met at the initiative of DCNS Research
with 15 experts and specialists to
initiate a constructive dialogue on risk
management, a key factor in innovation.
INDIA-FRANCE TECHNOLOGY SUMMIT
New Delhi (India), 23-24 October 2013.
Participation in the Technology Summit
and presentation of technological advances
and innovations, and also partnerships
with Indian universities (MoU).
From rapid prototyping…
to direct production!
Additive manufacturing, or 3D printing, combines all the processes enabling
a physical object to be produced from a digital object by adding material
layer by layer.
These numerous processes can be categorised by type of material (metallic,
polymer, ceramic, in liquid, powder, sheet or wire form) or by deposition technique
(seven major families including directed energy deposition and powder bed fusion
for metallic materials). This approach has a number of advantages: unrivalled
freedom of geometrical design, manufacturing of parts close to the final dimensions
and with short lead times. Current applications involve many fields, including
medical, tools, vehicles and fashion, as well as energy and aerospace.
The potential for applications at DCNS is very broad: for parts with complex
geometry, for coatings or even parts with composition gradients, for repairs in
EUROPORT 2013
Rotterdam (Netherlands) 5-8 November
2013. DCNS Research was at the
international meeting place for marine
science and technology. The programme
included improvement of energy
consumption and limitation of pollution
emissions.
METS 2013
Amsterdam (Netherlands),
18-20 November 2013. SIREHNA®
exhibited its latest innovations and
technological advances in the Super
Yacht Pavilion at the Marine Equipment
Trade Show.
OMAE 2013
Nantes (France), 9-14 June 2013. DCNS
Research was present at the OMAE 2013
forum to present its latest technological
advances and discuss the development
of the oceans with experts, researchers,
engineers, technicians and students.
new-build or maintenance, process on its own or in combination with others (hot
isostatic compaction of powders, for example), etc. Encouraging initial work has
already been done by DCNS Research to assess the potential of the process for
stainless steels and titanium alloys, and its technical and economic interest, in
particular for the manufacture of plate heat exchangers, difficult to produce by
conventional methods.
RESEARCH_2
OFFSHORE EUROPE 2013
Aberdeen (UK), 3-6 September 2013.
For the 40th anniversary of the Offshore
Europe show, attended by more
than 63,000 persons, DCNS Research
participated in talks on the theme “The
next 50 years”.
09
10
RESEARCH_2
PERFORMANCE
AT SEA AND
MARINE PLATFORM
DYNAMICS
Hull drag computation, model tests in a hydrodynamic basin, simulating the seakeeping characteristics of a structure, optimising propulsion units,
design of dynamic stabilisation systems, analysing
the launch of underwater weapons: this sector
embraces all activities enhancing the effectiveness
and reliability of powered and unpowered marine
platforms in mission execution.
RESEARCH_2
11
PERFORMANCE AT SEA AND MARINE PLATFORM DYNAMICS
Virtual Ship: integrated
ship design in the
preliminary project phase
AUTHORS: Benoît Rafine and Julien Bénabès
Virtual Ship is an R&D project initiated by DCNS Research. Its goal is the production of a software
environment for optimum whole warship architecture design in the pre-sale phase. Virtual Ship is
a multiphysical, multidisciplinary and multiscale collaborative digital integration platform. The
project is led by the CEMIS in collaboration with SIREHNA®.
Project context
The design of a naval system is one of the most complex major
industrial projects. For example, Le Terrible, the latest French
SSBN, weighing more than 12,000 tons, incorporates a million components; its construction requires 15 million hours
of work and involves 6,000 contractors under DCNS project
management. In comparison, a car weighing 1.9 tons has “only”
3,000 parts, with assembly requiring 23 hours of labour. The
construction budget of a warship is generally between 1 and 10
billion euros, for a limited quantity of 1 to 10 vessels with service lifetimes of around fi fty years. A warship must incorporate
a large number of subsystems and equipment items manufactured independently of the project. It also incorporates a very
large number of different and sometimes confl icting functions,
and it has to be able to operate in a hostile and hazardous
environment.
Many varied scientific disciplines are involved in the technical
and operational defi nition of the ship. These disciplines do not
handle the same design variables and do not need the same
level of detail nor the same computing time. Warship design is
consequently a multidisciplinary design activity, in which the
challenge for the naval system architect is to have an overview
of system performance in order to facilitate the design choices.
The preliminary “pre-sale” design phase is fundamental in the
overall design process of the ship. During this phase, there is
a close relationship between the customer and DCNS in order
to structure and clarify the customer’s need and identify the
optimum technical-economic configurations for the ship.
This phase provides the greatest freedom of design choices,
12
so innovative solutions can be explored. Lastly, knowledge of
the overall behaviour of the ship must increase rapidly in this
phase: the objective is to minimise the technological risks as
quickly as possible so as to control costs and be in a position to
submit a binding proposal to the customer.
Product control over the project life cycle.
Design Review
Contract
Development
Concept Design
Feasibility
Contract
Design
Definition
Validation
Contract
reference
cost
Budget
Assessment
System
knowledge
Design Review
Detailed
Design
Development
reference
cost
Production
reference
cost
100%
Ideal
Real
In this context, DCNS Research initiated the Virtual Ship
R&D project. The goal of the project is the production of a
multiphysical, multidisciplinary and multiscale collaborative
integration software environment for optimum whole warship
architecture design in the pre-sale phase.
RESEARCH_2
Meta-model
NATO Architecture
Framework
Technical Requests Rules
& Standards Environment
Budget Technology
Ship Concept Cost
Estimate Technology Plan
Models
Functional
Physical
(Digital
Mock-Up)
Behavioral
Probabilistic
NDMS
ASRU
EHCLS*
EHCLS*
Decoy launcher
DECOY'S
LAUNCHERS
Design Space
Mutli-physics
Simulation
Optimization
Strategy
Visualisation
Multi-objectives
Analysis
Architecture of the Virtual
Ship environment.
Objectives and expected results
The following main scientific results are expected for the Virtual
Ship project:
• better management, structured and shared at system level,
of the design requirements (customer need, manufacturing
constraints, budgetary constraints, etc.);
• connection between the functional modelling (requirements
and functions) of the ship and its digital mock-up (physical
description);
• seamless direct relationship between the ship performance
simulation results and the ship’s functional architecture;
• a more automated approach to the pre-sale phase in order to
shorten the response time and gain design study time;
• effective exploration (more complete and optimal) of the design
space;
• better justification and traceability of design choices;
• facilitation of knowledge management from the pre-sale phase;
• closer collaboration between the different entities involved.
Technological obstacles
The development of the Virtual Ship software platform necessitates the overcoming of several technological and industrial
obstacles, in particular:
• the production of a global warship architecture model: the
NATO Architecture Framework (NAF) will be adapted for description of the operational (customer need) and functional (ship
functions and technical requirements) sub-models. This NAF
will be connected to the physical model of the ship (physical tree
structure and digital mock-up);
• linkage and consistency of all the models contributing to the technical and operational definition of the ship. This involves enabling
dialogue between the ship performance models and the architecture
model of the ship itself (interoperability between models);
• seamless relationship between the whole warship architecture
modelling and the multiphysical simulation programmes in order
RESEARCH_2
to enable direct coupling between the functional analysis of
the ship and its requirements and the numerical performance
simulations;
• implementation of multiphysical and multidisciplinary optimisation strategies for Pareto-optimal exploration of the design
space under time and resource constraints;
• incorporation of often contradictory and sometimes subjective
expert opinions into collaborative decision-making;
• data management in a context of complex system and collaborative working environment;
• minimal modification of existing whole warship performance
models for their integration and use in the software platform;
• introduction of industrial constraints into the Virtual Ship tool;
• qualification of all the performance models and consistency of
the scope of their validity.
Virtual Ship is an ambitious project federating the activities of
DCNS Research. It is based on close collaboration with DCNS
engineering. The goal is to supply a practical aid tool for management of a complex system that imagination and experience alone
cannot grasp totally.
_REFERENCES
A. BOVIS. Naval Systems: The Virtual Ship. Proceedings of the CSD&M
Conference, 2013.
C. KERNS, A. BROWN, D. WOODWARD. Application of a DoDAF
Total-Ship System Architecture in Building a Design Reference Mission for
Assessing Naval Ship Operational Effectiveness. Proceedings of the ASNE
Global Deterrence and Defense Symposium, 2011.
M. BOLE, C. FORREST. Early Stage Integrated Parametric Ship Design.
Proceedings of the ICCAS Conference, 2005.
A. PAPANIKOLAOU, S. HARRIES, M. WILKEN, G. ZARAPHONITIS.
Integrated Design and Multiobjective Optimization Approach to Ship
Design. Proceedings of the ICCAS Conference, 2011.
13
MAX(1): generic
autonomous model
for submarine
manoeuvrability studies
AUTHOR: Jérémie Raymond
The hydrodynamic design of a submarine means that the skin shape has to be frozen very early in the
preliminary project phase. Digital methods are employed to test different hydrodynamic configurations
for a vessel project. They are used in the preliminary project phase to compare designs and rank their
performance. Nevertheless, the hydrodynamic design of a submarine remains an empirical science. It is
consequently not possible to rely completely on the digital approach. Once a design has unanimous
acceptance, it must be characterised in the “real” world, by testing. This is the stage at which the new
model MAX becomes involved. It can obtain this “real world” characterisation very rapidly. In addition,
several steering gear variants can be compared. MAX enables the analysis of complex manoeuvres that
cannot as yet be modelled by numerical simulations. It can also be used to validate computer codes and
is positioned as a development in parallel to and complementing the “digital tank”.
MAX: a multifunction underwater drone
Design and manufacturing, started in December 2011, were
cont r a cted by SM A En g i neer i n g to DCNS R ese a rch /
SIREHNA®, which is also responsible for operational implementation of MAX when it is in use. Simple and rapid to put
into operation, MAX is autonomous, autopilot-controlled
underwater and on the surface, reprogrammable for rapid testing of different confi gurations and adaptable to the hydrodynamic scales representative of the whole range of DCNS
submarines.
It can be used to:
• dimension the steering gear;
• perform manoeuvrability tests (DG, DT) for identification
of the mathematical model of the vessel;
• study the impact of specific appendages (stringers, deck
shelters, etc.);
14
• defi ne the control laws;
• conduct specific studies such as the effect of sea bed proximity on vessel behaviour.
2012 was spent designing the model, while 2013 saw model
assembly and qualification trials at sea.
General concept
The general concept adopted is that of a generic tool, i.e. easily
adaptable to the shapes and the characteristics of the DCNS submarine range. The model has a generic core structure comprising
a watertight aluminium body 4 metres long to which specific elements (bridge fin, external shapes, steering gear) of the submarine to be represented can be fitted. The assembled model is
between 7 metres and 10 metres long, according to the submarine being modelled, with a diameter of about 80 cm and a mass
of about 2 tons. Designed to operate at depths down to 70 metres,
the working depth is between 15 metres and 40 metres.
RESEARCH_2
Onboard systems
MAX has six independent actuators for rudder and plane control. Propulsion is handled by a 2 kW motor and the propulsion
unit is adaptable to each new project. Control and safety
device management functions are performed by two instrumentation and control computers. Test data is acquired by a
dedicated acquisition unit. An IMU90 inertial measurement
unit and an electromagnetic log give the speed and attitude of
the submarine at any time. The weight regulating system is
automatic, using a closed ballast. An acoustic communication
device is used to determine the approximate position of the
model when diving and tracking it during its movements.
A Wi-Fi communication system is used for control on the surface and test data retrieval as soon as the model surfaces and
for planning the next mission.
View of the steering gear.
Tests and initial conclusions
After a seven-month assembly and workshop acceptance phase
(January-July 2013), MAX went to sea for the first time in
September. For the occasion, it was con figured as the
Scorpene® Chile, a submarine for which a large volume of data
is available for comparing the behaviour of the model with that
of the real submarine.
The tests took place from September to November at the
La Ciotat site (between Toulon and Marseille). They validated
the major operational qualities of the model (ability to perform
complex manoeuvres, ease of use, productivity) and the representativeness of MAX with respect to the real submarine.
2014 prospects
With its shelter and dedicated test logistics, MAX can be
deployed rapidly to different sea or lake test locations. 2014
should see testing conducted by the SCO400 programme to
d i mension the steer i n g gear a nd for tests speci f ica l ly
designed to determine the manoeuvrability model. The possibility of using a torpedo version of MAX to study swim out
is also being considered.
A major development for DCNS, confi rmed by Vincent Geiger,
Deputy Director Deterrent Overall Architecture (AED) at
SMA: “MAX should divide the hydrodynamic design work
cycle time by two and the costs by four.”
MAX operating on the surface.
(1) In homage to the father of submarine manoeuvrability studies, Mr Max Aucher.
Max Aucher (Ecole Polytechnique, class of 1942), director of the Bassin d’essais
des carènes (model testing basin) from 1979 to 1982, completed the mathematical
model of submarine manoeuvrability, developed a method of extrapolation to full
scale of surface ship resistance and self-propulsion model tests, and contributed to
propulsion system noise reduction research.
Launching.
RESEARCH_2
15
16
RESEARCH_2
THROUGH LIFE
RESISTANCE
Throughout their working life, structures, whether
metallic or not, undergo natural or accidental
attack: corrosion, water impact, fire, shocks. Day
after day, they also face the phenomena of fatigue
and ageing. These attacks and other phenomena
call for calculations and testing to assess the durability of structures, as well as identify and try out
technological solutions to improve it.
RESEARCH_2
17
THROUGH LIFE RESISTANCE
Modelling
of mechanical propulsion
transmissions
AUTHOR: Romain Fargère
Power transmission is a major concern on a ship and affects the whole of the transmission system, from
the reduction gearbox to the propulsion propeller. Many factors are involved, including reliability, acoustic discretion and production cost. For an effective response to each of the issues, DCNS Research has
been working for several years on the development of dedicated numerical tools specifically designed to
take account of coupling between the various components and the physical processes. Used for a long
time in research applications, these tools are being rolled out in the engineering departments concerned.
They provide new perspectives, both in terms of working methods, favouring numerical/experimental
correlations, and in terms of design choices for the various components on future ships.
Power transmission
Power transmission is a concern with very major issues involving a number of complex components and consequently a number of physical processes: shaft lines, housings, gearing,
bearings, coupling components, etc.
Overall shaft line and housing vibration processes giving rise to
acoustic discretion problems are combined with very localised
processes. The latter mainly concern tooth contacts and bearings,
and necessitate particular attention in both the design and the
manufacturing phases.
Development
of dedicated tools
Propeller
(low speed)
without links between them, necessitating a large number of
manual iterations and providing a relatively simplified description of the physics of the problems. The increasingly demanding
discretion or cost constraints and the complexity of current systems make it necessary to develop new tools at the junction of
several fields of physics. These tools are being developed by the
DCNS Research engineers using an approach that can be summarised in a few main stages:
• problem analysis/literature survey;
• defi nition of equations;
Gearbox teeth in contact:
excitation
Gearbox casing
Excited shaftline
For a long time, DCNS has been
using high-performance tools
based on a high level of empiricism and on the experience of
its technicians and engineers.
More recently, with the development of numerical tools, the
engineering and design departments have had access to tools
w ith high performance but
18
Propeller
(low speed)
Fluid bearings
Schematic diagram of the transmission system of a ship.
RESEARCH_2
• digitisation/discretisation;
• development of the solving method;
• development of the communication interfaces (HMI).
An example of transfer:
reduction gearing simulation software
A hydrodynamic bearing software program has already been
transferred from the DCNS Research teams to the engineering
departments concerned, and a reduction gearing dynamic
behaviour simulation program is being transferred. The latter
software is also an example of collaborative work, as it has
been developed in part in collaboration with a laboratory that
has extensive experience on this topic: LaMCoS at INSA Lyon.
The tool in question comprises a human-machine interface
(HMI), facilitating data input and post-processing, and a computing core for setting up and solving a nonlinear secondorder differential system w ith parametric excitation of
the form:
HMI
PRE-PROCESSING
Geometry, meshing, running conditons...
Computing
code
Thermal
loop
Static calculation
Bearings
solutions
Time
increase
Update
teeth
contact
Solution of
linéarized
equation
Bearings convergence?
Teeth convergence?
POSt-PROCESSING (bearing reactions and
temperatures, tooth loading, varios coefficients…)
Gearbox behaviour simulation software architecture.
[M] Ẍ + [C] Ẋ + [K + Keng (t ; X)] X = Q + Qpal (X ;Ẋ) + Qeng (t ; X)
The difficulties raised by certain nonlinear terms (for example
contact terms such as bearings [pal] and gears [eng]) make it
necessary to develop a specific numerical method [1], based on
the substantial feedback from the university partner [2].
Tool qualification, the last stage before use
In general, these tools require a long qualification phase, to
which DCNS Research contributes. During this phase, each
function is tested according to a strict specification and the
results compared with proven results. To this end, a series of
experiments is carried out on a high-precision, high-power
(several hundred kW) test bench in order to compare the
results of simulations with the vibration, temperature, load
and other readings, supplementing a previous series [3].
From the point of view of the end user, this work remains
transparent, and in the end the users have a near-custom tool
meeting their specific needs in terms of both modelling precision and pertinence of the input and output data (loading
[time and spectral distributions and analyses], pressures, temperatures, etc.), enabling completely conventional application
of the tool in phases:
• parameter input;
• calculation by the tool;
• processing and interpretation of the results.
Conclusion
The work described above represents some of the tools applicable to
power transmission transferred to the engineering departments.
The development of extensions to these tools is under study
(gearboxes with complex architectures, bearings with various
geometries, housing behaviour, etc.). This work is evidence of the
RESEARCH_2
Single-stage reduction gear test bench.
importance of the links between DCNS Research and the
engineering departments, and of the role played by the research
partners of the Group.
_REFERENCES
[1] R. FARGÈRE: “Simulation du comportement dynamique des
transmissions par engrenages sur paliers hydrodynamiques”.
Doctoral thesis, Institut national des sciences appliquées de
Lyon, Villeurbanne, France, 203 p., 2012.
[2] P. VELEX, M . MATAAR: “A mathematical model for analyzing
the influence of shape deviations and mounting errors on gear
dynamic behaviour”. Journal of Sound and Vibration, 191(5),
p. 629-660., 1996.
[3] S . BAUD; “Développement et validations sur banc d’essai de
modèles du comportement dynamique de réducteurs à
engrenages à axes parallèles”. Doctoral thesis, Institut national
des sciences appliquées de Lyon, Villeurbanne, France, 194 p.,
1998.
19
Composite material
antenna systems
AUTHOR: Patrick Parneix
The SAMCOM collaborative project covers two aspects of the problem of insertion of antenna
functions into composite material structures: design of antennas made entirely of composite
materials, and most compact achievable integration of networked antenna elements into composite
material load-bearing structures.
Strong technical ambitions
Changing technical and operational needs are leading to
increasing use of telecommunications facilities and consequently of antennas on the platforms. This rapid increase is
generating growing integration difficulties: problems of
intrinsic performance of equipment (SWR(1)), masking problems, problems of electromagnetic compatibility between
systems, physical installation problems, signature (radar or
visual) degradation risks, problems of vulnerability in operational environments.
The ambition of the SAMCOM project is to provide solutions to
these various problems by means of composite materials and
technologies, and more specifically:
• by developing compact wideband communication antennas
usable at sea and on land;
• by developing methods for compact integration of antennas
and antenna arrays in composite panels.
Towards “custom” multifunctional composite
materials
For more than thirty years, radiocommunication systems operating in demanding environments have been using composite
materials successfully as framework and protection for the
metal radiating elements of antennas.
Making use of DCNS experience, for example in naval shipbuilding, the goal of the SAMCOM project is better exploitation of
the potential of composite materials: local adjustment of
radioelectric characteristics (dielectric, conducting, insulating, etc. materials), integration of periodic components or
patterns, multifunctional elements; in other words, production
of a “custom” composite panel.
20
Principal details of the SAMCOM project.
SAMCOM (composite material
antenna systems):
• collaborative project FUI 9;
• co-labelled by the EMC2 and Mer Paca clusters;
• DCNS Research project lead partner;
• 6 partners: Thales Communications
& Security, Institut d’électronique et des
télécommunications de Rennes (IETRUMR-6164, Rennes-1 university), Plastima
Composites, CERPEM, CEMCAT and DCNS;
• T0: 1/12/2010 – Duration: 54 months;
• DCNS teams involved: DCNS Research
CESMAN (lead), DCNS Research CEMIS;
• DCNS ING SMA, DCNS ING SNS (Composite
Developments – Communications
Department), SER Brest.
Each of the functions necessary for a composite antenna and
for installation of antennas or antenna arrays in panels imposes
specific requirements sometimes in conflict with the other
functions. Consequently, one of the essential steps in SAMCOM
is to compile the widest possible database of existing materials
or materials to be developed within the project. Substantial
work has been done by the IETR to develop reliable measurement methods for materials of very different natures and over
extended frequency bands.
In addition to the concepts of “conventional” materials, customary in composites even though here the performance targets
are very demanding, periodic material concepts such as highimpedance surfaces have also been considered.
RESEARCH_2
“All-composite” wideband antennas
The use of carbon fibre fabrics as radiating element(s) of antenna
structures has been investigated, initially in antennas with simple
geometry as illustrated below, then in more complex systems.
New communications antenna designs made entirely of composite materials have been developed both for civil applications
and for more specifically military applications. Prototypes of
each design are in the validation phase.
The developed antennas succeed in the challenge of obtaining
high microwave performance while achieving the initial objectives of compactness and frequency bandwidth. Operation of the
antennas in panels will be validated on demonstrators representative of their actual environment, in a civil context for land application and in a naval and military context (work planned in 2014).
Load-bearing panels favouring compact
antenna installation
The aim of this part of the project is to develop the necessary
technologies and defi ne the rules for installation of antennas in
composite panels, so as to:
• optimise the radiation patterns of the integrated individual
antennas;
• ensure decoupling enabling physical proximity of the antennas.
New solutions have been developed and will themselves be validated on the demonstrators mentioned above. This ultimate
phase of the project should enable evaluation of the ability of the
system to operate in an array and provide continuous search
capability, as well as the operation of the individual antennas in
different layout configurations.
A highly collaborative project
Like all the FUI (French single interministerial fund) projects,
SAMCOM is an applied research project aiming to develop
products or technologies likely to be put on the market in the
short or medium term. At this stage of the project, it is evident
that tangible advances have been recorded, some leading to
patent applications. Some of these advances are likely to be
exploited commercially in the short term, and perhaps even
before the end of the project.
The quality and the involvement of the partners, the support of
the co-funders (State, Pays de la Loire Region), the excellent
collaborative spirit favoured by the small number of partners,
their complementarity and geographical proximity are no doubt
the keys to the effectiveness of the project.
DCNS is taking an active part in the project, as lead partner
(DCNS Research) and also through the decisive contribution of
t h e t e a m s of t h e C E S M A N ( M a t e r i a l s), t h e C E M I S
(Electromagnetism), SMA (Engineering), SNS (Composite
Materials Workshop, Communication Systems Dept) and SER
(Brest Microwave Laboratory).
(1) Stationary wave rate.
_REFERENCES
P. PARNEIX. Systèmes antennaires en matériaux composites.
13es Journées de caractérisation micro-ondes et matériaux.
Nantes (France), 24-26 March 2014.
L. MANAC’H, X. CASTEL, M. HIMDI. Carbon-Fiber Tissue as Radiating
Element: Toward Pure Composite Materials Antennas.
“International Conference on Electronic Materials.”
IUMRS-ICEM 2012, 23-28 September 2012, Yokohama, Japan.
L. MANAC’H, X. CASTEL, M. HIMDI. “Performance of a lozenge
monopole antenna made of pure composite laminate.”
PIERS Letters. Volume 35, 115-123, 2012.
Example of evaluated conducting material.
Composite antennas with copper or carbon fibre radiating elements [2].
RESEARCH_2
Examples of the radiation patterns in different frequency bands
of an antenna array integrated into a composite mast.
21
Multifunctional composite
materials for
military naval applications
AUTHORS: Patrick Parneix and Mathieu Priser
The intrinsic properties of composite materials make them naturally multifunctional materials. These
properties were first exploited to produce lightweight non-magnetic structures, durable in the marine
environment. Gradually, the choice of components and the design of panels have been optimised in
order to make use of this multifunctionality, either through the use of fibres, resins and core materials,
themselves multifunctional, or by exploiting the capacity of composites to incorporate foreign components into their structure. This trend is growing, as increasing efforts are being made, often for reasons
of increased durability or performance, to incorporate into the panel itself functions previously externalised (mainly as coatings), or to design coatings that are themselves multifunctional. New material
concepts are emerging, such as “smart” materials and metamaterials.
Naturally multifunctional materials
The very fi rst applications of composite materials, and more
specifically in naval shipbuilding, were based on their absence
of corrosion and more broadly on their good ageing in the
marine environment. This property remains a strong argument for the durability of naval structures made of composites
and their moderate cost of ownership.
The non-magnetism of these materials was a determining factor
for their use as hull materials for minehunters. Lightness, low
thermal conductivity, transparency to acoustic waves: there are
many examples where the specific characteristics of composite
materials have led to structural applications, multifunctional
since the choice of the designer was guided as much by the
capacity of the composites to fulfi l a structural role as by the
particular function provided by this family of materials.
Towards “custom” multifunctional composite
materials
Step by step, the preoccupation with optimisation of structures has led to work on incorporating new functions into
composites by choosing the components no longer on the sole
criterion of their mechanical performance, but also on the
22
basis of other performance criteria for functions that they
would contribute to the end product. Furthermore, use has
been made of the ability of composites to incorporate into
their very structure foreign components providing a new function while minimising the impact on their mechanical performance. The development of production processes such as
vacuum infusion moulding is making a large contribution to
this innovation.
> New functions by incorporation of foreign components
into the structure
One of the earliest examples is the incorporation of the electromagnetic shielding function into dielectric panels. Various
technologies have been employed, such as the incorporation of
fine metal grids or metallised fabrics between the layers of
glass fibre composites.
The ability to incorporate sensors and to carry information on
the strain or the internal health of composite structures was
subsequently exploited, for example by means of optical fibre
Bragg gratings [1]. More recently, work has also been done on
other internal health monitoring methods, including the incorporation of piezoelectric sensors for obtaining information on
RESEARCH_2
Eridan-class minehunter.
SSBN/NG Le Triomphant.
local damage states of composite material structures [2] [3].
The antenna function is another function that can be incorporated. It will be seen below that recent work advocates antennas made entirely of composite materials. The insertion of
periodic patterns in composite panels can form frequencyselective surfaces, which can be used to produce frequency
fi lters for radome walls, for example.
Organic matrix composite materials show relative versatility
regarding their ability to incorporate foreign components.
Nevertheless, the “foreign bodies” introduced into the composite structure generally act as defects, the impact of which on
the overall mechanical performance of the panel should be
minimised.
> New functions through choice of components that are
themselves multifunctional
If the choice is available, preference is given to components
that are themselves multifunctional, in order to confer upon
the composite part purposes other than purely structural. For
electromagnetic shielding, for example, it is advantageous to
replace the grids by structural carbon fabrics. Antenna functions can be fulfi lled entirely using composite materials, and
decoupling between antennas incorporated into panels can be
achieved by using very specific composite materials. The use
of certain core materials and appropriate choices of reinforcing fibres or resins or panel designs results in load-bearing
structures that are transparent to electromagnetic waves or,
conversely, absorbent.
It is very clear that the choice of multifunctional components
offers greater assurances about the lifetimes of composite
material structures, and developments in naval shipbuilding
are moving significantly in this direction. The principal difficulty is to identify and qualify the right materials.
Future concepts
The search for multifunctional materials is particularly active in
all areas. In the naval area, three lines of development can be
highlighted:
RESEARCH_2
Insertion of
piezoelectric sensors.
Frequency-selective surfaces.
• continuation of incorporation within the structure of functions
at present more usually fulfi lled by coatings;
• development of smart materials, ranging from simple sensitive
materials to materials capable of reaction;
• emergence of new material concepts.
Following the logic leading to the search for increasingly functionalised load-bearing panels, it is natural to consider inserting
into the structures function previously handled by coatings.
Among the functions mentioned in this communication, the
example of radar stealth is significant. The thickness and the
sandwich structure of superstructure panels mean that various
absorbing structural panel designs can be considered, providing
broadband performance difficult to obtain with a simple coating. Incorporation of the function into the core of the structure
also provides an additional assurance of durability in comparison with coating solutions: no degradation of the absorbent, no
delamination, easier maintenance, etc.
The smart materials concept covers a very broad area which can
be defined as encompassing materials designed “with one or
more properties that can be changed significantly in a controlled manner by external stimuli such as mechanical stress,
temperature, humidity, pH, magnetic or electrical fields (currents), etc.” All of these functions are evidently of interest to naval
shipbuilding for various applications, and work has been undertaken from the early 1990s. The evolution towards increasingly
autonomous smart materials is a major line of development, mainly
in the areas of acoustics and electromagnetism: adaptive acoustic
materials (piezoelectricity, electrorheology), adaptive microwave
materials (stealth, antenna incorporation, etc.), nanotechnologies.
Over the last few decades, new material concepts have emerged.
These materials draw their characteristics from their sub-wavelength-scale structural elements rather than from the intrinsic
properties of their constituents. They form a new category of
materials, with properties that cannot be found in natural
23
materials. These metamaterials fi nd applications in many areas
of physics, and more particularly in electromagnetism, even
though new concepts are starting to emerge in acoustics.
This was the context in which DCNS funded the work for a thesis defended in 2013 entitled “Étude des interactions élastoacoustiques dans des métamatériaux formés d’inclusions
résonnantes réparties aléatoirement” (Study of elastoacoustic
interactions in metamaterials formed of randomly-distributed
resonant inclusions) [5]. This work showed that particle local
resonance mechanisms in an elastomer matrix could be
exploited to increase the performance of hull acoustic coatings.
This may turn out to be of particular interest in the area of low
frequencies, by adjusting the geometry of the particles and the
constituent materials.
Radial stress field related to a dipolar
resonance mechanism of a core-shell
particle subjected to an incident
acoustic wave [6].
In-pool characterisation of the
reflection and transmission
coefficients of acoustic panels
consisting of a random dispersion
of spherical particles.
The basic principle applied in these materials is to use the substructure (random or periodic) of the material to generate interferences between objects at this sub-scale and produce apparent
“exotic” properties at a macroscopic scale, representative of the
material. Nevertheless, these materials usually show effectiveness in a relatively narrow band related to the characteristic size
of their substructure (pitch of a periodic array, size of the
objects of a random structure, etc.). One of the challenges is
consequently to be able to demonstrate these properties over a
broader frequency range.
At present, metamaterials are a very active research topic and
one of the keys to overcoming the technological barriers to the
invisibility cloak concept, which would provide military naval
structures with a level of stealth (radar or acoustic) constituting
a technological breakthrough compared with present levels.
In conclusion, as in other areas, the composites employed in
naval shipbuilding are evolving rapidly. Over time, there has
been a transition from multifunctionality limited to exploitation
of the natural properties of these materials to a “targeted” multifunctionality, leading to complex panels themselves constituting integrated systems. New concepts are emerging, making use
of unsuspected properties, shaking up the conventional perceptions and classifications in the field of materials. Obviously
DCNS has to be active in this area, as illustrated by the example
of the thesis mentioned above.
24
_REFERENCES
[1] M. BUGAULT, P. FERDINAND, S. ROUGEAUD, V. DEWYNTERMARTY, P. PARNEIX, D. LUCAS. Health Monitoring of Composite
Plastic Waterworks Lock Gates Using in-Fibre Bragg Grating Sensors.
4th European Conference on Smart Structures and Materials,
Harrogate, United Kingdom, July 1998.
[2] M. GRESIL, P. PARNEIX, M. LEMISTRE, D. PLACKO, J.-C. WALRICK.
Lamb wave propagation in a hybrid Glass/Carbon composite
laminate for electromagnetic shielding. 7th International Workshop
on Structural Health Monitoring, Stanford, United States,
September 2009.
[3] M. GRESIL, P. PARNEIX, M. LEMISTRE, J.-C. WALRICK, D. PLACKO.
Effet de l’insertion de blindage électromagnétique sur la
propagation des ondes de Lamb dans un composite à renforts
de fibres de verre. 16e Journée nationale sur les composites,
Toulouse, June 2009.
[4] P. PARNEIX, M. PRISER. Matériaux composites multifonctionnels
pour applications navales militaires. ATMA 2013, Paris.
[5] G. LEPERT. “Étude des interactions élasto-acoustiques dans des
métamatériaux formés d’inclusions résonnantes réparties
aléatoirement”, doctoral thesis, I2M, Bordeaux, December 2013.
[6] G. LEPERT, C. ARISTÉGUI, O. PONCELET, T. BRUNET, C. AUDOLY
and P. PARNEIX. Study of the acoustic behavior of materials with
core-shell inclusions. Journées anglo-françaises d’acoustique
physique (AFPAC) conference, Fréjus,January 2013.
RESEARCH_2
ENERGY
OPTIMISATION
At a time when fossil fuel is becoming rarer and
more costly, it is vital to consider all solutions to
reduce energy consumption. This entails shape
optimisation of hulls, energy saving control systems,
lightweight structures, or even recovering a vessel’s
stabilisation energy. New energy, including marine
renewables, in search of higher yields, are also at
the forefront of research solutions to recover energy
better, and to store and transfer it.
RESEARCH_2
25
ENERGY OPTIMISATION
Optimised operation
of ships: simulations
and optimisations
AUTHORS: Charles-Édouard Cady and Christophe Gaufreton
As part of the EONAV FUI project, a decision support tool has been developed to provide recommendations
for optimising the control of a ship. The tool generates savings of around 2% on the fuel consumption of a
ship. Three types of optimisation are currently being developed: speed, electrical load-shedding and
generator load optimisation. The genericity of the architecture used enables other types of optimisation
(e.g. refrigeration, water production) to be accommodated.
Introduction
Changes in international regulations (target of a 20% reduction of
CO2 emissions by 2020) and the lasting increase in the cost of oil
are leading all shipbuilding industry leaders to propose innovations to improve the energy efficiency of ships both in the design
phase and in operational use.
The EONAV optimised ship operation system for reducing energy
consumption and emissions is a response to this concern with
protection of the environment and with control of energy costs for
ship operators. The emphasis placed by DCNS Research on
energy optimisation conforms to its strategic development priority for managing tomorrow’s energy issues and for broadening its
range of innovating products.
Decision support tools (DST)
Optimisation
The EONAV system has been designed to help a crew optimise the
energy management of a ship through various levers: optimum
speed, configuration of the generating plant and configuration of
the electrical substations for load-shedding. Other optimisations
such as water production and trim can be added to these in order to
improve performance, but speed management is a major factor, as it
accounts for 60% to 80% of the total energy consumption of a ship.
DST energy model
The core of the application is based on a complex multiphysical
energy model of the ship comprising the following components:
• hydrodynamic model incorporating the environmental constraints;
26
• mechanical model containing the “propulsion” part of the ship;
• electrical model including the generators and the loads;
• thermal model including the cold/heat producers and the loads;
• emission model.
The optimisation algorithms use all or part of the energy model to
minimise fuel consumption. The reduction of emissions is a direct
consequence of the lower fuel consumption.
User modes
With the energy model of the ship, there are three DST user mode
options:
• planning mode: for voyage preparation, recommending optimum speeds for the various routes and suggesting electricity
generating plant configurations according to operational activity and system availabilities;
• monitoring mode: used during the voyage for displaying the
environmental indicators (EEOI, CO2, SOx and NOx) and for
following up the recommendations. The tool adjusts and
updates the optimisation solutions according to the route
actually followed and to be taken;
• analysis mode: for analysing and comparing completed voyages
using the data recorded by the system. It contributes to the
SEEMP imposed by the regulations. This mode can also be used
to compare the model with the recorded data and detect any
drift in the equipment.
RESEARCH_2
ENERGY OPTIMISATION
Monitoring mode HMI.
Speed
Technical innovations
Design of a formal computing core
The optimisation algorithms require the calculation of gradients,
Jacobians and Hessians. These functions can be coded manually,
but this takes a long time, is a source of error and is not very
maintainable. For these reasons, a formal calculation core has
been developed specifically for this task. It uses principles derived
from the λ-calculation, with simplifications applied when the
expressions are defined in order to keep the computing time close
to that of direct coding.
Manipulation of embedded simulators
A simulator manipulation grid has been produced making it
easy to add models and force values (or even replace a model by
playback of recordings in real time) without having to establish
a nd ma i nta i n con nections bet ween models ma nua l ly.
To achieve this, a forward/backward chaining algorithm automatically infers the dependencies between the modules.
Substantial performance gains are achieved using a lazy evaluation algorithm.
average
Time
Start
End
Speed
average
Time
Start
End
Speed
Optimisations performed
Speed
The speed profile, with respect to the seabed and for a defined
route, is optimised taking into account the environmental forces.
Each speed profile is simulated and the profiles are compared
according to the total fuel consumption that they generate on the
trip. To reduce the size of the domain to be explored, speed profiles
RESEARCH_2
average
Time
Start
End
Profile of speed over bottom on defined track.
27
ENERGY OPTIMISATION
that are constant by segment are applied, and refined recursively
while keeping the total trip time constant.
Diesel generators
The electrical load is distributed between the diesel generators so
as to minimise total instantaneous consumption. This is done
using consumption/load curves which can be manipulated as
mathematical functions thanks to the formal computing core. A
solver implementing the inner point method is then used to solve
the optimisation problem.
Load shedding
The electrical loads to be connected to the network are optimised
taking into account their importance (vital, semi-vital, non-vital)
and their propensity to disturb the network. Mathematically, this
is a linear discrete problem under linear constraints which is
solved using a linear programming solver. The formal computing
core enables this problem to be written simply.
Functions
supplied
such that
supplied
requested
Optimization problem
Recommendation example: the breakers marked in red correspond to the differences between the current state and the proposed optimisation.
Conclusion
The tool has been validated using consumption data recorded on
the cruise ship Norwegian Epic. The saving was calculated by
comparison between the actual and optimised consumption on
the same voyage. The results show that the decision support tool
improved fuel consumption by 2% on a ship with an already substantially optimised design. The cost optimisation is derived from
the application of speed optimisation and electrical energy production optimisation.
This project is an initial step in ship energy management using
decision support tools. These results enable ship consumption
and emission reductions of 5% to be targeted by adding new optimisation strategies: refrigeration, water production, trim, etc.
Lastly, the decision support tool using energy indicators is a response to the regulations for ship operators, enabling them to
manage the energy efficiency management plans of their ships.
28
RESEARCH_2
ONBOARD
INTELLIGENCE
Faced by increasingly complex maritime operations
related to reduced crews, operators must be supported
by partly or completely automated systems, using
advanced control rules, which need to be constantly
improved and adapted to new situations. Security and
energy saving requirements are also to be integrated
into control algorithms and system architectures. If we
push this logic further, we enter the world of drones or
unmanned vehicles (UxVs), autonomous devices capable
of carrying out tasks without human intervention.
RESEARCH_2
29
ONBOARD INTELLIGENCE
Architecture of
a guidance system for
autonomous vehicles
AUTHOR: Denis Gagneux
The use of aerial drones (Unmanned Aerial Vehicles) has grown exponentially over the last few years. Long
restricted to military uses, they are now becoming available in the civil sector.
Surface drones (Unmanned Surface Vehicles [USV]) and underwater drones (Unmanned Underwater Vehicles [UUV]), complementing aerial drones, have also seen their use become more
widespread. They save manpower, either for carrying out repetitive tasks or for work in hostile environments. Since the early
2000s, combining its knowledge of marine platforms and automatic pilots, SIREHNA® (DCNS Research) has been contributing
to this revolution through its work on guidance systems.
The guidance systems are the heart of autonomous vehicles.
Developed by SIREHNA®’s engineers for marine drones, these
software and hardware architectures are the fruit of a decade of
research work and experimentation. USVs and UUVs are autonomous vehicles that can be used in very diverse environments,
ranging from secured zones (reserved exclusively for the drone)
to zones of dense maritime traffic (ports, commercial shipping
routes, etc.). In the near future, the adaptability of the level of
autonomy of these drones will enable military and civil users to
vary their uses: as remote-controlled vehicles, as vehicles whose
movements are monitored by remote operators, and as fullyautonomous vehicles. The architecture of their guidance systems enables all navigation requirements to be met, while
ensuring the safety of the vehicle and of its environment.
vehicles or objects in its environment. If an abnormal event is
detected, the secondary computer takes control of the vehicle in
order to make it safe. It is powered by a different, redundant
power source from that of the main computer, so that it can be
operational in the event of main system electrical failure. It is
also linked with a remote supervision station via a dedicated
communication link separate from the one used by the main
computer, enabling an operator to take action in the event of
failure of the main system communication link. The technology
used for the communication link depends on the environment of
the autonomous vehicle. If it operates on the surface, a microwave link is used, while for underwater operation the link is
acoustic. The architecture may incorporate various sensors to
avoid collisions with objects in its environment: radar, AIS, laser,
video camera or sonar (the only sensor that can be used on
underwater vehicles). The technologies of these sensors are
complementary, increasing the vehicle’s perception of its
environment.
The guidance system consists of a main computer
(Command & Control) and a secondary computer
(Safety)
The main computer performs the functions related to navigation,
for example by incorporating an autopilot. The secondary computer ensures the safety of the vehicle and of its environment: it
checks the consistency of the commands output by the autopilot
and detects vehicle failures and potential collisions with other
30
RESEARCH_2
ONBOARD INTELLIGENCE
Graphic interface of the supervision station. The operator monitors the movement of the vehicle using the digital map module.
The architecture is currently deployed on a surface drone (Remorina) and on a non-tethered underwater model (MAX).
RESEARCH_2
31
32
RESEARCH_2
INFORMATION
MANAGEMENT
The expanded use of electromagnetic, optronic and
acoustic sensors in diverse operational situations
has led to tremendous increases in data availability.
Effective information management has thus become
essential and now requires automated processes for
better localisation, identification, characterisation and
tracking. The underlying goal is to provide operators
with reliable, relevant and real-time information that
exposes the best possible decision.
RESEARCH_2
33
INFORMATION MANAGEMENT
New data
association processing
solutions
AUTHOR: Olivier Marceau, Daniel Vanderpooten(1) and Jean-Michel Vanpeperstraete
The sensors on board a vessel supply descriptive measurements of the objects around the platform. The
data association function plays a key role in obtaining a synthetic representation of the environment of
the vessel on the basis of these measurements. Work at DCNS Research aims to propose data association
processing solutions which consume kinematic and qualitative information, without constraining
assumptions (scan assumption) about the structure of the sensor measurements on reception.
Description of the problem
The data association function of a multisensor system (radar,
infrared imager, etc.) is a critical technical component of
search management. While each sensor supplies elementary
information (positions, angles, identifications) describing the
targets that it has detected, the data association function aims
to combine information from sensors which designate the
same target.
(
).
describes the accumulation of
scans:
(1)
Mathematical modelling of the association problem
All the measurements are assumed to be made at fi xed times
with
A candidate hypothesis models a combination hypothesis for
measurements that designate the same target. More precisely,
is defi ned as a subset of measurements from
such that:
(in reality, the measurements are generally asynchronous). At each
time , the sensor supplies a set of measurements called a “scan”.
where
is the number of measurements received in scan and is the
-th measurement received in scan . The composition of a measurement depends on the sensor: for example, a 2D radar measures
the distance and the azimuth angle of each potential target
34
for any
.
(2)
(3)
(2) indicates that each candidate hypothesis cannot contain
more than one measurement of each scan.
(3) states that a candidate hypothesis contains at least one
measurement.
RESEARCH_2
The quality of a partition is assessed through the quality of
its constituent candidate hypotheses
. Each candidate hypothesis of partition describes a combination of
kinematic measurements
which is more relevant the
more consistent the measurements are with a kinematic
behaviour of the targets to be detected. This kinematic consistency is assessed using a probability
Candidates
hypotheses
.
The optimum partition is thus the one that maximises a consistency criterion of the following form ([9]):
(7)
Tracks
Measurements
Figure 1. Examples of candidate hypotheses.
where designates the set of partitions
and (6).
The output of the data association processing is a set
sisting of
candidate hypotheses.
con-
(4)
must form a partition
The candidate hypotheses
of
. In other words, each measurement of
belongs to
one, and only one, constituent candidate hypothesis of .
for any
(5)
(6)
Candidates
hypotheses
satisfying (4), (5)
Problem (7) is a discrete optimisation problem, which has no
guaranteed exact solution in polynomial time for all instances
where
is strictly greater than 2 ([9]). This optimisation problem in fact belongs to the category of NP-complete problems
([4]).
Solving the association problem
Equations (1) to (7) constitute the standard mathematical
model of the data association problem. When the number of
dimensions equals 2, the data association problem corresponds
to the classic assignment problem, for which there are very
effective exact polynomial algorithms (e.g. [1,2]…). Many publications (e.g. [3,5,8,9]…) propose algorithms that are suboptimal
but efficient in terms of computing time when the number of
dimensions is strictly greater than 2.
Despite the large number of solutions available, DCNS
Research is developing innovative solutions for associating
data, for the following main reasons:
• the scan structure constraint;
• the use of qualitative data.
Tracks
Measurements
Figure 2. Example of partition.
RESEARCH_2
The scan structure constraint
The scan concept is central to the modelling of the association
problem, and most algorith ms make critical use of the
concept.
The scan models how the sensor measurements are presented
to the data association processing. In the case of a rotating
radar sensor, the scan is the set of measurements acquired
during one complete antenna rotation. However, today operational problems are arising where the asynchronism of the
measurements renders the modelling constraint imposed by
the scan structure problematic. To deal with this problem,
35
DCNS Research has developed innovative and particularly
effective data association methods which are not constrained
by the scan concept.
The use of qualitative data
Most of the publications describe solutions which automatica l ly process the k i nematic measu rements (d ista nce,
azimuth), the errors of which are characterised by a statistical
model.
In contrast, few publications ([6]) describe solutions for using
qualitative information that is not characterised in statistical
terms. Identification information is an example of qualitative
information. However, qualitative data can be an essential
additional information source for improving data association
processing.
Thanks to a partnership with the Lamsade laboratory, DCNS
Research has obtained promising initial results on the use of
qualitative data ([7]).
DCNS Research is continuing its work with Lamsade in order
provide technical data association solutions in the medium
term capable of using the available qualitative information
(1) PSL, Paris university Dauphine, Lamsade, place du Maréchal-de-Lattre-deTassigny, 75775 Paris Cedex 16.
_REFERENCES
[1] D. P. BERTSEKAS: “The auction algorithm: a distributed relaxation
method for the assignment problem”. Annals of Operations Research,
vol. 14, p. 105-123, 1988.
[2] R. BURKARD, M. DELL’AMICO, S. MARTELLO. Assignment Problems,
SIAM 2009.
[3] A. CAPPONI: “Polynomial time algorithm for data association
problem in multitarget tracking”. AES IEEE, p. 1398-1410, 2004.
[4] M. GAREY, D. S. JOHNSON: Computers and Intractability.
A Guide to the Theory of NP-Completeness. Ed Freeman.
[5] H. GAUVRIT: “Extraction multipistes : approches probabiliste
et combinatoire”. Thesis, Rennes university, 1997.
[6] H. HUGOT, D. VANDERPOOTEN, J. M. VANPEPERSTRAETE:
“A bi-criteria approach for the data association problem”.
Annals of Operations Research, vol. 147, no. 1, p. 217-234, 2006.
[7] O. MARCEAU, J. M. VANPEPERSTRAETE: “Automatisation
des traitements et aides à la décision”. Internship report, 2013.
[8] K. R PATTIPATI, S. DEB, Y. BAR-SHALOM,R. B. WASHBURN:
“A new relaxation algorithm and passive sensor data association”. IEEE
Trans on Automatic Control, vol AC-37, no. 2, p. 198-213, February 1992.
[9] A. POORE: “Multidimensional assignment formulation of data
association problems arising from multitarget and multisensor
tracking”. Computational Optimization and Applications, p. 27-57,
1994.
36
RESEARCH_2
Tracking
manoeuvring targets
in 3D
AUTHOR: Dann Laneuville
Surveillance systems, the purpose of which is to determine the tactical situation in an extended zone
covered by search sensors, and tracking systems focusing on a particular object, are sometimes confronted
with particular situations in which certain objects in the scene are highly manoeuvrable. This may be the
case of a personal watercraft or an inflatable boat in the context of asymmetric threat countermeasures, or
of an ASBM (antiship ballistic missile) in the context of ABMD (antiballistic missile defence), for example.
Such manoeuvres, combined with the potential presence of
false alarms, are a real problem for the tracking algorithm,
which may “lag”, showing an estimation bias (loss of precision), or even break lock, i.e. lose the track of the pursued
object, obliging the system to regenerate the track after a possible search phase in the event of tracking. In both cases, the
loss of performance can prove fatal if a threatening target has
to be engaged. Consequently, the availability of a robust, highperformance manoeuvring target tracking algorithm appears
to be an essential component of surveillance and tracking
systems. The purpose of this work is to study a new algorithm
for tracking a manoeuvring target that can manoeuvre vigorously in two or three dimensions.
State of the art
The state of the art in manoeuvring target tracking algorithms
is represented by the IMM (Interacting Multiple Model) fi lter
introduced in the 1990s ([2]). This is a recursive algorithm
using several Kalman fi lters in parallel, each dedicated to a
particular phase of the trajectory, for example a fi lter for the
uniform movement phases (constant speed = no manoeuvre)
and a fi lter for the manoeuvre phases, such as uniform turns
(in which the speed does not var y and the turn rate is
constant). This fi lter has recently been revised to take strict
account of the case of fi lters of different dimensions in each
mode ([7]), as will be the case here, and improved in its
approach with respect to the optimum filter ([5]) with the
RESEARCH_2
GMIMM (Gaussian Mixture based IMM), which retains the
most probable r hypotheses in each mode, whereas the IMM
merges them all into a single hypothesis.
Today, the two most widely used models in an IMM fi lter are
the NCV (Nearly Constant Velocity) model, which describes
the u n i for m movement phases w ith state vector ([1])
X(t) = [x y z vx v y v y]’, and the NCT (Nearly Coordinated
Turn) model for the coordinated turns in the horizontal plane
([1]) with state vector X(t) = [x y z vx v y ω]’ where ω is the
turn rate in the plane. Until [3], the turns tracked by the IMM
were in the horizontal plane. The recent approach developed
in [3] also enables manoeuvres to be tracked in a vertical
plane, but at present no fi lter satisfactor i ly processes
manoeuvres made simultaneously in the two planes (genuinely 3D manoeuvres). That is the goal of our approach.
New approach
The two models above are described at present in Cartesian
coordinates (CC) in the literature. We propose a new mixed
representation: Cartesian for the position and spherical for the
speed.
This gives state vector X(t) = [x y z s ψ θ]’ for the fi rst model,
where s is the modulus of the speed, ψ et θ are the two angles
defi ning the direction of the speed vector (see fi gure 1 below),
and X(t) = [x y z s ψ θ ω1 ω2]’ for the second model, where ω1 is
37
Figure 2. Scenario 1.
38
RESEARCH_2
the turn rate in the horizontal plane and ω2 is the vertical turn
rate.
the second-order discretisation of which is given by ([6]):
dx1 = x 4 sin(x5) cos(x6)dt
x1D = x 01 + tx 04 sin(x5) cos(x 06)
t x x cos(x ) cos(x )
+—
05
06
2 04 07
2
t
– — x x sin(x ) sin(x )
2
dx2 = x 4 cos(x5) cos(x6)dt
dx 3 = x 4 sin(x6)dt
2
dx 4 = σ 1 dW1
08
05
06
x2 D = x 02 + tx04 cos(x 05) cos(x 06)
dx5 = x 7 dt
t x x sin(x ) cos(x )
–—
05
06
2 04 07
t2 x x cos(x ) sin(x )
–—
2
dx6 = x 8 dt
dx 7 = σ 2 dW2
04
and
dx 8 = σ 3 dW3
2
04
08
05
06
(3)
t2 x x cos(x )
x3D = x 03 + tx 04 sin(x 06) + —
06
2 04 08
x 4D = x 04
x5D = x 05 + tx07
Figure 1. Speed in spherical coordinates.
x6D = x06 + tx08
x 7D = x07
x8D = x 08
The corresponding models of change over continuous time are
given by the following stochastic differential equations:
dx 4 = σ1 dW1
dx5 = σ2 dW2
Examples of results
dx 4 = σ1 dW1
and
dx6 = σ 3 dW3
dx5 = x 7 dt
For further details of the discretisation of (1), and in particular the stochastic part, refer to [4] from which this summary is
derived.
(1)
dx6 = x 8 dt
dx 7 = σ 2 dW2
The results of two IMM fi lters, each using the two models NCV
and NCT, are compared, the fi rst (IMM1) in Cartesian coordinates and the second (IMM2, new approach) in mixed coordinates. A radar, symbolised by a blue triangle on the scenario
curves, supplies the 1 s rate of the distance measurements,
where σr = 20 m, and circular and elevation angle measurements, where σang = 10 mrad.
dx 8 = σ 3 dW3
These models have the general form of a stochastic differential
equation:
dXt = a(Xt) dt + b(Xt) dWt
(2)
In the fi rst scenario, the target performs a manoeuvre in the
horizontal plane with a turn rate of 0.2 rads -1 at a speed of
250 ms-1, giving a load factor of 5 g. The performance of the
two IMM fi lters is illustrated in the left-hand graph. It can be
seen that the new approach significantly improves the performance in comparison with what is at present the best filter
(IMM1) for manoeuvres in the horizontal plane.
In the second scenario, the target performs a manoeuvre in a
vertical plane with the same turn rate of 0.2 rads-1 at the same
speed of 250 ms-1, giving the same load factor of 5 g. It can
again be seen that the new approach significantly improves
the performance.
RESEARCH_2
39
In the third scenario, the target performs a 3D manoeuvre, i.e.
in both the horizontal and vertical planes, with a turn rate of
0.2 rads-1 in both planes and at a speed of 250 ms-1, giving a
load factor of 7 g. It can again be seen that the new approach
behaves as well as previously (manoeuvre in one of the two
planes) and significantly improves the performance.
Conclusions and prospects
We have presented a new approach to modelling the manoeuvres
of a target, which not only improves performance on coordinated
turn manoeuvres in the horizontal or vertical plane, but also
maintains the same level of performance on genuinely 3D
manoeuvres. This approach, more natural and more physical
than Cartesian coordinates for modelling the manoeuvres of a
moving object, consequently appears to be very promising for
manoeuvring target tracking applications. Subsequent work
consists in incorporating it into a tracking algorithm in order to
test it in a multitarget environment with false alarms and detection gaps.
_REFERENCES
[1] Y. BAR-SHALOM, P. WILLETT and X. TIAN. Tracking and Data
Fusion. A Handbook of Algorithms. YBS Publishing, 2011.
[2] H. A. P. BLOM, Y. BAR-SHALOM. “The interacting multiple
model algorithm for systems with Markovian switching
coefficients”. IEEE Transactions on Automatic Control.
33, p. 780-783, August 1988.
[3] J. GLASS, W. D. BLAIR, Y. BAR-SHALOM. “IMM Estimators with
Unbiased Mixing for Tracking Targets Performing Coordinated
Turns”. Proceedings of IEEE Aerospace Conference, Big Sky,
United States, March 2013.
[4] D. LANEUVILLE. “New Models for 3D Maneuvering Target
Tracking”. Proceedings of IEEE Aerospace Conference, Big Sky,
United States, March 2014.
[5] D. LANEUVILLE, Y. BAR-SHALOM. “Maneuvering Target
Tracking: A Gaussian Mixture Based IMM Estimator”.
Proceedings of IEEE Aerospace Conference, Big Sky, United
States, March 2012.
[6] A. TOCINO and J. VIGO-AGUIAR. “New Itô-Taylor expansion”.
Journal of Computational and Applied Mathematics, 158,
p. 169-185, 2003.
[7] T. YUAN, Y. BAR-SHALOM, P. WILLETT, E. MOZESON,
S. POLLAK and D. HARDIMAN. “A multiple IMM approach with
unbiased mixing for thrusting projectiles”. IEEE Transactions
on Aerospace and Electronic Systems, 48(4):3250-3267,
October 2012.
40
RESEARCH_2
Innovation
and human factors
AUTHOR: Chantal Maïs
Taking human factors into account in the design of complex systems is necessary in order to ensure
optimum operation. For warships, high-technology systems that are very complex to operate involving
both individual and collective performance, in a harsh environment and in stress situations, it is a major
issue: the effectiveness of the crew-ship unit in fulfilling its missions.
In this view, the innovations must
improve and increase the capabilities
of the ships.
What does taking the “human factor” into
account contribute to innovation?
It is necessary to:
• identify the “level” of innovation: system
upgrade or technological breakthrough?
• characterise the type of innovation:
technological, organisational, individual
(related to the individual person)?
But, whatever its nature, any innovation
has an impact on the human aspects.
This impact must be assessed sufficiently
early in the design process to:
• choose the appropriate ty pes and
methods of human factors involvement;
• conduct the upstream HF studies, when
the predicted impact is high, in order
to anticipate new uses, ensure the acceptability of the innovation and manage the
change, in addition to the more conventional criteria of HMI usefulness and
usability.
DCNS at the cutting edge of virtual reality.
Innovation and human factors
When thinking of innovation, the main things that come to
mind are technological and technical innovations.
These innovations enable the development of increasingly
automated and even autonomous systems (drones, for
example), but also provide access to large quantities of data
from multiple “big data” sources. New interaction techniques
RESEARCH_2
such as augmented reality, virtual reality and touch screens
offer new modes of interaction.
These innovations entail modifications, changes and/or
breakthroughs in how systems are used. The acceptability of
such innovations is an important point to be taken into
account, in addition to the utility and usability aspects.
These changes entail changes in human organisations (in particular geographically-distributed collaborative or cooperative
organisations, or access to low-level data and no longer only
41
summary data for the decision-making levels, etc.), and
changes in the allocation of tasks between individuals (potentially with reduction of workforce) or in practices.
But innovation is not limited to technological innovation. Any
change at the level of the individual (changes in tasks, change
in profile), at the level of a collective (workforce reduction,
decentralised organisation), or at the level of the company
(company development) can also be seen as an innovation, the
impacts of which on the future users must be analysed and
anticipated, incorporating the following data:
• the various human aspects – anthropometry, physiology,
cognition, conation, sociology, etc. – are not mutually independent. Their interactions in part determine the behaviour
(and potentially the performance) of the users. For example,
the confidence users have in the system can modify how they
interact with the system;
• individuals differ from each other in the various aspects.
This interindividual variability generates different requirements, needs and behaviours;
42
• individuals change over time in the various aspects. As they
gain experience, they acquire new knowledge, modify their
cognitive structures, etc.
In a user-centred approach, it is necessary to predict the
impacts on the users, including on future practices, through a
validation procedure (mock-up/evaluation) with the users as
far upstream as possible.
At DCNS, a company with a high level of technicality, innovation is most often considered in terms of technology. Taking
human factors into account not only guides innovation, but is
also a source of innovation!
RESEARCH_2
STEALTH AND
ANTENNA
INTEGRATION
How can you be somewhere without others being
aware of your presence? How can you prevent disturbing the environment through which you are moving?
Whether in the field of electromagnetics or acoustics,
there are several technological solutions to choose
from. These call for special materials, carefully designed
forms, positionings and judicious decoupling. Seeking
and identifying these solutions requires upstream
modelling of the phenomena involved, using tools and
methodologies capable of being updated to keep pace
with threats and analytical needs.
RESEARCH_2
43
STEALTH AND ANTENNA INTEGRATION
Vibroacoustic
radiation by plates
in transient states
AUTHORS: Thomas Leissing, Roch Scherrer and Christian Audoly
The use of acoustic waves at sea for detection of enemy forces by means of passive sonar has been
widespread for decades, and sonar technology is evolving constantly. The upgrading of passive sonars,
now capable of analysing transient noise, makes it necessary to optimise acoustic discretion in nonsteady-state conditions. DCNS must consequently be capable of specifying transient acoustic discretion
requirements for equipment and their support structures installed on vessels. In this context, DCNS
Research is working on the study of vibroacoustic radiation mechanisms of structures in transient states,
for example in a doctoral thesis in partnership with the INSA-Lyon acoustic vibration laboratory. The
objective of this study is to improve knowledge in order to represent the mechanisms of vibroacoustic
radiation of structures in transient states in terms of radiation sources, transfers and factors.
Solving method
To study the vibrations and the acoustic radiation of an
immersed structure excited by a transient source, a simple
structure is considered first: an infinite plate. The plate is
immersed and subjected to a point pulsed excitation. The
movement of the plate is expressed by the Love-Kirchhoff
equation [1,2]:
where D is the bending stiffness of the plate,
and h are respectively the density and thickness of the plate, ω is the angular frequency, ξ is a structural damping term, w(r,t) represents
the displacement of the plate as a function of the distance
from the excitation source and time, f 0 is the amplitude of the
exciting force at location r 0 and p(r,t) is the parietal pressure.
Particular attention must be paid to the viscoelastic damping
model, which must obey the causality principle. Solving this
equation for the dynamics of thin plates in harmonic states
gives the movement of the plate in the frequency domain. An
inverse Fourier transform is then applied to obtain the pulse
44
response of the plate and the pressure radiated in the fluid in
the time domain. A schematic representation of the solving
principle is shown in fi gure 1.
Application to an immersed infinite plate
The method used is validated by comparison with a plate in a
vacuum, for which there are analytical solutions [3]. The study
of vibration on an immersed plate shows the effect of the fluid,
the dispersion of the plate waves and the fluid/solid interface
waves. The study of the radiated pressure shows directivity of
the radiation and propagation of the waves in the plate before
being radiated.
An example of simulation of an immersed aluminium plate is
shown in fi gure 2. The pressure levels in the fluid at four different times can be seen (left to right and top to bottom:
t = 0.23 ms, t = 1.40 ms, t = 2.79 ms and t = 6.12 ms). The planar plate is located along z = 0, so its edge is represented by
the black dotted line. The exciting force consists of a pulse at
(t = 0, z = 0). The colour map shows the pressure levels in the
fluid. The propagation of the waves in the fluid can be observed in the four panels. Four virtual hydrophones are placed in
RESEARCH_2
STEALTH AND ANTENNA INTEGRATION
Unknown transfer function
Source
Answer
Fourier
Transform
Inverse Fourier
Transform
Source
Answer
Transfer function known
Figure 1. Schematic representation of the solving method.
Figure 2. Simulation of the pressure field radiated by an immersed infiDinite plate excited by a point force.
RESEARCH_2
45
the fluid medium; they are represented by the filled black
circles. The signals received at these points are shown on
time/amplitude graphs. It can be seen that the temporal characteristics of the signals differ greatly according to the distance between the excitation point and the observation point.
The signal received by the nearest receiver (bottom-left) is
very short, practically a pulse, whereas the signal observed by
the receiver located bottom-right has a smaller amplitude, a
longer duration and a more complex frequency content. This
simulation reveals, for a simple case, various physical processes that would be difficult to identify and interpret in a
frequency representation.
Prospects
The case of the infinite plate can be used to validate the
models and the numerical methods developed, but is not sufficiently representative of the complex mechanical systems on
board ships. In order to approach as closely as possible to real
structures, the case of fi nite plates, beams and their coupling
is also being processed by methods similar to those described
here. In addition, experiments are being carried out on immersed plates in an acoustic tank; these measurements will be
used to validate the simulation models developed in this study.
Fine-tuning and experimental validation of these models and
tools will enable the DCNS Research teams to obtain finer
characterisation of the vibration and radiation processes of
structures subjected to pulsed excitations. Eventually, it will
be possible to apply these methods to the design of ships for
acoustic discretion in transient states.
_REFERENCES
[1] M. C. JUNGER, D. FIET: Sound, structures and Their
Interaction. Second ed., Cambridge: The MIT Press, p. 235-250,
1986.
[2] X. L. BAO, H. FRANKLIN, P. K. RAJU, H. UBERALL: “The splitting
of dispersion curves for plates fluid-loaded on both sides”.
Journal of the Acoustical Society of America. 102 (2), 1997.
[3] R. SCHERRER, L. MAXIT, J.L. GUYADER, C. AUDOLY,
M. BERTINIER: Analysis of the Sound Radiated by a Heavy Fluid
Loaded Structure Excited by an Impulsive Force. Internoise
2013, Innsbruck, Austria, September 2013.
46
RESEARCH_2
PRODUCTIVITY
AND
COMPETITIVENESS
OF INDUSTRIAL
PROCESSES
Industrial processes affect all product manufacturing
activities and components, broadly encompassing the
choice of materials, manufacturing techniques, assembly and appropriate testing methods. Such processes
include the extensive use of virtual or augmented reality,
i.e. reliance on modelling and visualisation methods to
choose the best path forward, well upstream of the prototype phase. Moreover, the changes taking place in the
way overall production chains are organised, in incorporating new manufacturing technologies, has prompted
research into the “future factory” and the “extended
factory” within many industrial sectors.
RESEARCH_2
47
PRODUCTIVITY AND COMPETITIVENESS OF INDUSTRIAL PROCESSES
Evaluation of friction stir
welding (FSW) on high yield
strength steels for shipbuilding
AUTHORS: Guillaume Rückert, Myriam Chargy, François Cortial and François Jorez
FSW process has been evaluated on three shipbuilding steels (DH36, S690QL and 80HLES steels) by fullypenetrated butt welds on 8 mm thick plates. Non destructive tests were carried out to highlight the
presence of intrinsic defects known for the welding process (e.g. kissing bond). The validated inspection
methodology (volume and surface testing) confirm the integrity of welds and the absence of geometrical
defects for examinations and mechanical tests as part of a qualification procedure.
Introduction
The competitive market of naval vessels requires more efficient
designs and manufacturing conditions in order to increase industrial and service performances. In particular the improving of the
manufacturing conditions and the weight saving can be achieved
by innovative design and processes. The use of performance materials such as high yield strength (HYS) steels in shipbuilding (hull,
superstructures, floatboard, propellers…) is a solution which allows
a significant weight saving by reducing the structures thicknesses.
The manufacturing processes must accordingly adapt to the characteristics of these grades. In this context, the development of
innovative welding processes must also be conducted ensuring the
quality of assemblies: limitation of weld defects, limitation of distortions and improving the flatness of structures, improvement of
hygiene and safety with regard to manufacturing processes, better
controllability, improvement of serviceability and repairing.
The fusion welding processes used in shipyards could require preheating, generally a filler metal, and lead currently to defects (lack
of fusion, porosity, inclusions, cold cracking) or geometric defects
on the surface (undercuts…), as well as distortions of structures.
These defects undertake works, for repairing and/or finishing. The
friction stir welding is an alternative method that uses solid-phase
48
welding without filler metal, which eliminates the disadvantages
associated with metal fusion. While there are still many scientific
and technological locks, the FSW is a mature technology for homogeneous and heterogeneous aluminium alloys [1] assembly. The
main applications in the field of shipbuilding concern assembly
extruded shapes to form stiff floors [2]. Studies [3, 4] have demonstrated the importance of this process in low alloy steels for a thickness of about 6 mm to 12 mm, for the grain refi nement in heat
affected zone (HAZ), an enhancement of the metallurgical weldability with regard to arc welding processes, and producing no welding fumes, particularly containing hexavalent chromium.
However, the results are derived from laboratory works on small
specimens and do not demonstrate the industrial feasibility, taking
into account the operating conditions in general and the use of tool
with limited life (based tungsten-molybdenum) in particular. The
recent developments of technologies coming from drilling tools
(poly-crystalline boron nitrides – PCBN – doped W-Re), proposed
by MegaStir lead to a technology breakthroughs [5]. Studies related
to the use of these promising tools are limited to the work of the
team behind the tool invention and limited mechanical performance materials [6]. To our knowledge, concerning welding of HYS
steels required especially for shipbuilding, no study has been
published to date.
RESEARCH_2
This study presents an evaluation of this innovative welding process for both civil and military shipbuilding applications. The main
objective is to demonstrate that the FSW process technically and
economically meets the specific requirements of the shipyards.
Indeed, the introduction of this process in the workshop can be
done only if its interest is demonstrated in terms of quality and
manufacturing costs, controllability, health and safety of personnel
dealing with proven and economically viable processes. It is therefore necessary to verify that the process is robust and repeatable,
and that it can satisfy the required performances of the assemblies.
The present study focused on three steels currently used for
French naval application: two high yield strength steels (S690QL
and 80HLES, a French grade close to HY100) and a DH36 steel,
employed for hull and structures. The presentation provides a characterisation of the welded joints for optimised welding parameters
and a complementary analysis to consider a future industrialisation
of the FSW process in our shipyards.
Experimental procedure
Materials
Three grades of steel (two high yield strength steels and one
construction steel) used for hull and structure applications have
been selected for this study according to their respective mechanical properties:
• DH36 steel, a structural steel for hull according to Bureau
Veritas NR 216 [7];
• S690QL steel, a structural steel according to standard
EN 10025-6 [8];
• 80HLES steel, a French equivalent grade of HY-100 steel for hull
and structures.
The following tables give respectively guaranteed values for
mechanical properties and chemical composition for each grade.
Table 1. Guaranteed values for mechanical properties for DH36,
S690QL and 80HLES steels
Grade\Mech.
properties
YS* (MPa
– ksi)
DH36
S690QL
80HLES
UTS** (MPa – ksi)
El.*** %
355 – 51.5
490-620/71-90
21
690 – 100
770-940/112-136
14
700 – 101.5
780-900/113-130
14
* Yield strength. ** Ultimate tensile strength. *** Elongation.
Table 2. Chemical composition for DH36, S690QL and 80HLES steels
% max
(pds)
DH36
C
Si Mn P
S
0.18 0.50 1.60 0.035 0.035
N
B
–
–
Cr Cu Mo Nb Ti
–
–
–
–
–
V
–
Ni Zr
–
–
S690QL 0.18 0.50 1.60 0.020 0.010 0.015 0.005 0.8 0.50 0.70 0.062 0.05 0.10 2.0 0.15
80HLES 0.15 0.25 0.50 0.01 0.01
–
–
0.5
0.25 0.40
–
–
0.09
4.8
–
Welding process
The butt welding tests (with full penetration) have been performed
RESEARCH_2
with a Gantry machine on 1,500 x 150 x 8 mm plates on the three
grades, joined together in the lengthwise (rolling direction).
Friction stir-tool in PCBN based material comprises a threaded
shoulder (25 mm diameter) prolonged by an 8 mm long threaded
conical pin.
Non-destructive tests (NDT) and mechanical tests
Characterisation tests were carried out in order to compare the
performance of the FSW process with arc-welding processes for
which the expected performances are known. The introduction
of welding processes in manufacturing requires a welding procedure qualification (WPQ), the rules and requirements are
governed by codes or standards. For shipbuilding steels, the
ISO 15614-1 standard [9], dealing with the qualification of welding
procedures for arc welding of steels offers a level of minimum
requirements.
NDT required in this context are two complementary types of
tests, i.e. volume testing and surface testing on 100% of the weld.
These tests are always preceded by a visual inspection which, in
the case of FSW, can identify unacceptable defects like partial
penetration type, or lack of recovery, burrs… For the volume
part, digital radiographic testing (X-rays) are preferred to ultrasonic testing because of the welded thickness. Indeed, for 8 mm
thick welds, the resolution of the X-rays is much better. For surface measurements on the upper and lower surfaces of the weld,
penetrant and magnetic particle testings are performed. The
surface of the weld can cause background noise, especially for
dye penetrant testing. It is often necessary to grind the surfaces
before examinations.
Destructive tests are performed to ensure that the weld does not
cause significant change in the characteristics of the assembly.
Transverse tensile tests (two specimens), transverse bend tests
(two specimens per face – upper and lower –, bending angle 180°)
impact tests (V-notch at –20 °C) and Vickers hardness (HV5)
were carried out according to [9] and associated standards cited
by this standard. For impact tests, specimens are machined on
the nugget and the thermo-mechanically affected zone, i.e. TMAZ
(three specimens per batch). For hardness tests, two rows of
indentations were made at a depth of up to 2 mm below the upper
and lower surfaces of the welded joint (at least 3 individual indentations in each area). In addition, complementary longitudinal
tensile tests have been carried out on the nugget in order to characterise the stirred zone.
Results
NDT tests
Specimens welded during preliminary testing dedicated to settings of welding parameters have been used to validate that
radiographic testing is relevant to indicate the volume defects
which may appear in FSW such as internal voids. Defects such as
kissing bonds, which are not detected by visual examination
49
(figure 1.a) or penetrant testing, are revealed through magnetic
particles testing. Figure 1.b illustrates this observation by the
presence of a black vertical line in the middle of the weld corresponding to a discontinuity of the magnetic field lines. It could be
related to incoherence in the microstructure between the two
edges to be welded, confirmed by micrographics on cross-section
coupons (figure 1.c). The ACFM (alternating current field measurement) method is an alternative method to magnetic particles
testing for kissing bond examination. This typical defect in FSW
caused particular developments in innovative techniques for aluminum alloys. The magnetic nature of the steel allows the application of simple and proven methods to ensure the absence of
kissing bond.
(a)
(b)
Destructive tests
In this study, the selected areas for mechanical tests on each
grade of steels are free of NDT indications. Tensile tests on
transverse specimens lead systematically to a failure on the
base material. For DH36 steel, the two specimens exhibit respectively tensile strength values at 512 and 513 MPa (742 and
744 ksi) at 20 °C. The ultimate tensile strength reached on longitudinal tensile specimens (on nugget) is about 700-712 MPa
(101-103 ksi). It confi rms a significant gap in mechanical behaviour between the base material and the nugget, explained by a
severe thermo-mechanical cycle constituting a Widmanstätten
microstructure, as shown in fi gure 2.a. Elongations values are
not too much affected (22% and 24% in the nugget) and slightly
higher than the requirements for the base material (i.e. 21%).
We can expect such behaviour for welded S690QL and 80HLES
steels, each exhibiting a very hard martensitic structure as
shown in figure 2 for 80HLES steel and confirmed latter by
hardness tests (table 4) for both steels.
Bend tests are discriminating enough for kissing bond (when the
upper surface is stretched); without defect, no indication upper
than 3 mm, with respect to the standard [9], is noticeable.
Macroscopic examinations on the three welded steels conclude to
a defect free nugget. No internal or geometric defects were noted
in observation areas. In retreating side, it could appear, as shown
in fi gure 3 for 80HLES steel, a lack of thickness, but well below
the acceptance criterion (i.e. 0.1 t from [9]). Burrs may appear
locally (corresponding with areas exhibiting a lack of thickness).
If the lack is acceptable, we just remove the burr by grinding.
Impact tests results are given in table 3 for DH36 steel. Values in
TMAZ are slightly lower in retreating side (two individual
values around 35 J), probably associated with the conditions of
the bond formation to the back of the stir tool. The base material exhibits values upper than 70 J. Values obtained on the
friction stirred weld are systematically lower than those for base
material. In arc weldi ng, the mean values of absorbed
energy vary between 40 J and 100 J, according to the processes
50
(c)
Figure 1. Kissing bond defect on DH36 steel; no indication by visual
examination of the lower surface (a), indication (black vertical line in the
middle of the weld) in magnetic particles testing on the lower surface (b),
observation on cross-section micrograph (c).
(a)
(b)
Figure 2. Micrograph on friction stirred nuggets; DH36 (a) and 80HLES (b).
Figure 3. Macrograph of the friction stirred weld on 80HLES steel (advancing
side on left side).
and welding energies. The FSW process leads to results with
similar magnitude than arc welding process, consistent with the
elongation values previously identified and consistent with
requirements of Bureau Veritas (i.e. 34 J at –20 °C) [7].
Table 3. Impact test (V-notch) results (individual and mean values)
for DH36 steel at –20 °C
Nugget
Middle
upper side
79
71
64
TMAZ
Middle
lower side
42
61
57
65
TMAZ/Nugget interface TMAZ/Nugget interface
advancing side
retreating side
78
50
45
49
51
35
59
33
42
Hardness tests results are shown in table 4 for the three
welded steels. These results indicate a hardening in nugget
and affected zones (HAZ/TMAZ) related to thermal and
mechanical conditions imposed during friction stir welding,
even more pronounced when the steel is susceptible to quenching (as shown in figure 2.b for 80HLES steel). However,
large increases in hardness for S690QL and 80HLES steels are
compatible with the requirements specified in the standard [7].
There is no significant difference in results between advancing
and retreating side. The dispersion in results into the nugget,
particularly between upper and lower rows, even in a same row
(e.g. S690QL steel), can be explained by the coexistence of
different mixed areas.
RESEARCH_2
Table 4. Hardness test results (HV5) in friction-stirred welds
for DH36, S690QL and 80HLES steels
Advancing side
Grade
Location
BM
Retreating side
HAZ/TMAZ Nugget HAZ/TMAZ
BM
Upper
row
178
172
178
187
202
229
214
202
211
220
212
221
192
181
186
Lower
row
172
169
169
188
195
202
202
205
199
207
198
188
174
173
176
Upper
row
279
277
268
374
374
386
393
416
413
399
386
378
277
290
294
Lower
row
279
263
271
391
445
435
395
418
430
430
440
375
268
266
269
Upper
row
277
275
276
410
441
433
421
410
431
440
438
433
275
275
280
Lower
row
279
277
268
374
386
393
416
413
399
386
383
378
277
290
294
DH36
S690QL
80HLES
Permitted
maximum
value [7]
380
450
450
Conclusions
Preliminary investigations on three friction-stir welded steels
were performed in order to confirm the applicability of the innovative FSW process for shipbuilding steels.
The main results of this study are:
– NDT tests (volume and surface testing) are proposed for the
examination of the qualification coupons and manufacturing
assemblies; in particular, the application of magnetic particles
testing which is a common and simple to perform accurate and
relevant test to the detection of defects such as kissing bond;
– for DH36 steel, a complete character isation has been
performed and concludes on a good behaviour of the welded
joints, compatible with the minimum charges required in
shipbuilding.
– the first partial results on S690QL and 80HLES steels are
encouraging; welds can be free from defects and hardness rows
display results in compliance with the requirements. However,
microscopic observations exhibit complex structures related to
the thermo-mechanical cycle and the primary structures of
steels that can lead, in the worst case, to an excessive fragility
of the weld. It requires further investigation in progress to
understand the formation mechanisms of the different areas
and accordingly optimise the welding parameters.
Acknowledgements
This study is part of SIPSAN project supported by IRT Jules
Verne (French Institute in Research and Technology in
Advanced Manufacturing Technologies for Composite, Metallic
and Hybrid Structures). Authors wish to associate the industrial
and academic partners of this project, respectively DCNS, STX
France, Bureau Veritas, GeM Institute (UMR CNRS-ECNNantes University 6183); IMN Institute (UMR CNRS-Nantes
University 6502).
Authors wish also to thank gratefully MegaStir (Provo, USA) for
the achievement of friction stirred welds.
RESEARCH_2
_REFERENCES
[1] R. RAI, A. DE, H. K. D. H. BHADESHIA ET T. DEBROY. “Review: friction
stir welding tools, Science and Technology of Welding and Joining”,
Volume 16, no. 4, p. 325-342, February 2011.
[2] K. J. COLLIGAN, M. T. SMITHERMAN, S. B. HOYLE. “Low-cost friction
stir welding for littoral combat ship applications”. Naval Engineers
Journal, March 2009.
[3] T. J. LIENERT, W. L. STELLWAG, B. B. GRIMMETT, R. W WARKE. “Friction
stir welding studies on mild steel”. Welding Journal, Volume 82, no. 1,
p. 1-9, January 2003.
[4] T. SHINODA, H. TAKEGAMI et al. Development of FSW Process for
Steel Assemble to Shipbuilding and Off shore Structure. Proceedings
of the 15th International Off shore and Polar Engineering Conference,
Seoul, Korea, 19-24 June 2005.
[5] J. DEFALCO, R. STEEL. “Friction stir process now welds steel pipe”.
Welding Journal, Volume 88, no. 5, p. 44-48, May 2009.
[6] C. C. TUTUM, J. H. HATTEL. “Numerical optimisation of friction
stir welding: Review of future challenges”. Science and Technology
of Welding and Joining, Volume 16, no. 4, p. 318, 2011.
[7] NR 216 DT R06 E. “Rules on Materials and Welding for the
Classification of Marine Units”, edited by Bureau Veritas,
February 2013.
[8] EN 10025-6 standard: Produits laminés à chaud en aciers de
construction – Partie 5 : conditions techniques de livraison pour
les aciers de construction à résistance améliorée à la corrosion
atmosphérique (Hot rolled products of structural steels – Part 5:
Technical delivery conditions for structural steels with improved
atmospheric corrosion resistance), edited by Afnor, March 2005.
[9] ISO 15614-1 standard: Descriptif et qualifi cation d’un mode
opératoire de soudage pour les matériaux métalliques – Épreuve
de qualifi cation d’un mode opératoire de soudage – Partie 1 : soudage
à l’arc et aux gaz des aciers et soudage à l’arc des nickels et alliages
de nickel (Specification and qualification of welding procedures for
metallic materials – Welding procedure test – Part 1: Arc and gas
welding of steels and arc welding of nickel and nickel alloys), edited
by Afnor, February 2005.
51
The development
of TOFD
at DCNS
AUTHOR: Patrick Recolin
One of the missions of DCNS Research is the development of new non-destructive testing techniques in the
laboratory followed by their deployment on the Group’s production and maintenance sites. The growing
use of the TOFD ultrasonic technique is an illustration of this.
TOFD (Time of Flight Diffraction) is an ultrasonography technique
using two transducers (a transmitter and a receiver) placed either
side of a weld (figure 1). In combination with an encoding system,
this system can rapidly obtain an image of the weld, which is comparable to a cross-section view of the weld (figure 2).
This technique originated in the 1980s in the United Kingdom. It
has been under study at DCNS since the 1990s and used for the
first assessments on onboard nuclear steam supply systems from
1995 (figure 3). Many other developments have taken place since
then, and the TOFD technique is now widely employed when
necessary in the context of in-service monitoring (figure 4).
For hulls, discussions with the UK MoD were initiated in 1995, in
which one of the major topics was the replacement of radiography
for hull weld inspection. The discussions resulted in various benchmarks for comparing and improving testing procedures and equipment. At the time, DCNS carried out various statistical studies [1]
demonstrating the high level of effectiveness of the ultrasonic
technique. These studies, backed by all the studies conducted
during the same period in other fields (petrochemicals, offshore,
etc.), led DCNS to propose the TOFD ultrasonic technique to
French defence procurement agency DGA as an alternative to
radiography for submarine hull weld inspection. Reduction of
radiation sources was of course a major objective, but the productivity gain obtained by increased concurrent activity in the construction phase was the other important factor.
Coordinated by DCNS Research, a team combining ultrasonics
experts, engineering and the production site compiled a supporting documentation package which was finally accepted by the
customer in 2012 (figure 5) [2]. Feedback is today considered
52
positive by the various entities involved: ultrasonic examination
provides greater flexibility in the manufacturing process while
ensuring detection sensitivity at least equal to that of radiography.
A similar approach is now introduced for certain joints in the hulls
of surface ships. The difficulty in this case is to ensure examination
of the whole volume required on non-flush joints of low thickness.
In parallel with this work, DCNS Research is continuing to develop
TOFD, for example by incorporating multi-element technology [3].
The beam focusing and deflection capabilities enable new applications to be considered, such as examination of austenitic joints [4]
and inspection of very thick joints (up to 200 mm).
_REFERENCES
[1] P. RECOLIN, S. RIVALIN, Y. LEZIN. Utilisation de TOFD pour
le contrôle des joints de coque, COFREND 2001.
[2] B. MARIE, P. RECOLIN, B. LEYRONAS, A. LEBIEZ. Remplacement
de la gammagraphie par les ultrasons sur des soudures
de coques, COFREND 2011.
[3] S. RIVALIN, P. RECOLIN. Application de la technologie des
capteurs ultrasonores multi-éléments au suivi de soudures
de collecteur vapeur, COFREND 2005.
[4] P. RECOLIN, S. RIVALIN, B. MARIE. Examen partiel en TOFD
d’une soudure austénitique, COFREND 2011.
RESEARCH_2
– Control TOFD L45 L60
Figure 1. Typical TOFD configuration.
Figure 2. TOFD image of a welded joint.
Figure 3. First assessments.
Figure 4. Inspection of the containment of the aircraft carrier.
Figure 6. Use of multi-elements in TOFD.
Figure 5. Inspection of a hull joint.
RESEARCH_2
53
Biofilms and corrosion
of corrosion-resistant alloys
in sea water
AUTHORS: Émilie Malard, Hervé Gueuné, Jean-François Ghiglione, Christelle Caplat,
Valérie Debout, Zakoua Guede and Chantal Compère
Nickel-based alloys (e.g. Inconel 625 – base Ni, 22% Cr, 9% Mo, Nb) and austenitic-ferritic duplex steels
have been used extensively for applications in sea water since the 1980s. These alloys are specifically
resistant to all forms of uniform corrosion. Nevertheless, they may be sensitive to localised corrosion and
in particular to crevice corrosion.
Feedback from users, including DCNS, shows that this type of
corrosion occurs in all the oceans and seas around the world
and at any time of year. It is characterised by an increase in the
free corrosion potential and the generation of a corrosion current between the “crevice” zone (seal, flange, pump, heat
exchanger, etc.) and the metal surface outside the crevice, as
shown in fi gure 1.
Figure 1. Crevice corrosion of alloy 625 in natural sea water
on a flange and at the metal/seal contact.
These increases in potential and current have
been eliminated by application of biocides. This
provided evidence of the involvement of biofi lms
formed in the systems, leading to a focusing of
research on a more specific study.
The objective of this project, supported by French
defence procurement agency DGA through the
REI exploratory research and innovation scheme,
was to understand the role of the biofi lm in the
crevice corrosion processes on Inconel 625. The
project involved multidisciplinary characterisation of biofi lms formed on alloy Inconel 625 under
controlled conditions leading to active or inactive
biofi lms. The diversity of bacterial species in each
biof i l m was a na lysed, as wel l as its phy toplanktonic diversity, its chemical composition
(lipids, carbohydrates, amino acids, mineral and
54
STRUCTURAL
ORGANISATION
Bacterial abundance
Microscopic Observation
Area Coverage
PHYTOPLANKTON
DIVERSITY
GLOBAL
CHEMICAL COMPOSITION
Lipids, glucids ,
Amino acids
Inorganic elements
Hydrogen peroxides ( H2O2 )
Multidisciplinary
Characterization
BACTERIAL DIVERSITY
DNA fingerprinting
Taxonomic Identification
ENZYMATIC
ACTIVITIES
Lipase, glucosidase
aminopeptidase
Figure 2. Test plan.
RESEARCH_2
metallic constituents, oxidising molecules) and its spatial organisation, according to the test plan in fi gure 2.
Difference observed on samples A: active and NA:
Not active on the structure of the bacterial biofilm
The fi rst stage of the study consisted in conditioning surfaces
using an electrochemical method in order to obtain “active”
biofi lms on samples showing a high cathode current and “inactive” biofi lms on samples showing an open-circuit potential of
300 mV/SCE but a low cathode current.
Nearly 700 samples were conditioned for analysis. All the biofi lm characterisation analyses illustrated in fi gure 3 were perfor me d on s a mple s a t d i f fer e nt t i me s of ye a r (f r om
November 2011 to end-2012).
The multidisciplinary characterisation observed differences
between “active” and “inactive” biofi lms, including:
• higher concentration of microorganisms in the “active” biofi lms, associated with greater coverage of the surface of these
active samples in the form of aggregates;
• greater diversity of bacterial communities present and active
in the “inactive” biofi lms;
• fatty acid composition mainly comprising saturated fatty
acids in the “inactive” biofi lms and mainly comprising monounsaturated fatty acids in the “active” biofi lms;
• higher concentrations of some mineral or metallic constituents in the “active” biofi lms;
• higher aminopeptidase enzyme activity in “active” biofi lms
than in “inactive” biofi lms.
Biofilm stained with DAPI (4’,6-diamidino-2-phenylindole: staining of
the DNA) and observed with an Apotome fluorescence microscope.
The results obtained for each type of analysis show the same
trend.
Statistical analysis was used to select specific criteria of “active”
and “inactive” biofi lms.
The overall results obtained suggest selection of metabolicallyactive bacterial populations, apparently related to the active character of the samples and/or leading to activation of the samples.
Preliminary analysis of the 454 pyrosequencing results identified
the predominant bacterial populations in the active biofi lms as
related to the species Halomonas venusta and Halomonas sp.
(class Gammaproteobacteria, order Oceanospirillales, family
Halomonadaceae).
Figure 3. Illustration of test results.
RESEARCH_2
55
Digital engineering
and future shipyard
AUTHOR: Alain Bovis
The acceleration of worldwide competition both in shipbuilding and in the marine renewable energy
sector necessitates, as the CORICAN (French council for the orientation of research and innovation in
shipbuilding and related activities) has stressed in its roadmap, the development of new design and
production methods intended to increase the competitiveness of this industrial sector. DCNS Research
is heavily involved in this development in a very broad collaborative framework, in particular with the
IRT Jules Verne, competitiveness clusters EMC2 and Systematic, and academic and industrial partners in
all sectors of activity.
Digital engineering
For almost three centuries, DCNS has been designing, on a
scientific basis, and building, in outstanding industrial facilities, warships recognised in each epoch as among the most
complex systems produced by humans. They are complex in
terms of the technologies used and the scientific tools necessary for their design calculations, complex in terms of the
number of specifications with which they have to comply,
around 150,000 today for a front-line ship, and complex in the
number of equipment items and individual components
(1,000,000). They are also complex in terms of the variety of
trades and the number of contributors involved in their production (the system supplier and integrator accounts for only
20% to 40% of the added value of a ship). Last but by no means
least is operational complexity in a difficult environment, the
ocean, and in a context of widened and increasingly integrated
cooperation (system of systems concept).
Naval architecture thus appears as a precursor of what is
today called “system engineering”. A warship is an assembly of
subsystems and equipment units, but any naval architect
knows from experience that it is not limited to the sum of
these subsystems and equipment units. The integrated ship,
comprising both the “carrier” component, the platform and its
propulsion, and the “disposable load”, the combat system, has
major properties, referred to as cross-functional performance,
which cannot be obtained or analysed from the building
blocks: this is the case for the overall hydrodynamic performance, the various signatures (acoustic, electromagnetic,
56
infrared) and, more generally, the overall operational capabilities that confer tactical superiority.
The design of a complex ship is an iterative sequential process
consisting of consecutive phases during which the defi nition of
the ship, its dimensions, its constituents and their layout is
refi ned until the detailed working drawings are produced. The
fi nal detailed design must satisfy all the requirements of the
owner. The design process extends over several years and
does not end until after performance verification at sea on the
first of class vessel, which is also always the prototype.
However, very early in the process, contractual agreement on a
price and a delivery date has to be reached between owner and
prime contractor. This commitment is generally made on completion of the fi rst phase, referred to as the “feasibility study
phase”, during which the main characteristics of the ship are
established, the technical sticking points and specific development needs are identified, and the project costs and duration
are estimated. Although ideally it might be hoped that at this
stage 80% of the elements determining the defi nition of the
ship be known, leaving 20% as estimates, in practice barely
more than 50% of such elements are known at this stage with
sufficient precision, both because of requirement drift and
because the need for new technological developments opens
up a wide range of risks for the prime contractor.
Extensive use of digital engineering can significantly shorten
the feasibility study phase, thereby allowing exploration of a
much larger volume of the envelope of possible confi gurations.
RESEARCH_2
The convergence of simulations of different mathematical
types, necessitating different representations of the same ship,
is in itself a complex problem. One solution is to reproduce the
different simulations in a single surrogate model with a very
large number of parameters. The objective is to be able to
explore the largest number of possible confi gurations in order
to identify the optimum solution taking account of all the
requirements and their priorities. This is a multiphysical,
multiobjective optimisation approach.
It provides the architect, the customer and the main future cocontractors with a platform for collaborative exchanges and
speeds up the transition to the “digital mock-up” for detailed
defi nition studies.
At the level of complexity encountered, joint management with
the customer of the countless requirements necessitates the
development of what are called “metamodels”, or “architecture
models”, of the type developed by the American Department of
Defence and adopted by NATO in the field of software systems
(DoDAF, NAF). These models are used to set boundaries on
the envelope of possible variation of the design parameters.
Today, with its academic and industrial partners, DCNS
Research is focusing on the development of computing and
algorithm resources leading to a design optimisation tool.
The design itself, based on the digital defi nition of a confi guration, requires the development of simulation tools: physical simulation of cross-functional performance (hydrodynamic, acoustic,
EMC, shock and impact response behaviour, vibration behaviour,
etc.), functional simulation of systems (propulsion, weapon systems, etc.), behaviour simulations (human factors), statistical
simulations (fatigue, ageing, obsolescence, etc.). DCNS Research
is engaged in several programmes to develop such tools, for
example the “digital tank”, new vibro-acoustic models and functional simulations of energy and propulsion systems.
Future shipyard
The construction of a ship is similar to a major public works
project in that the object built is unique, or at best only a small
number will be produced. And even in the latter case, the
spreading out over time of the different units or the special
requirements of different customers generally leads to significant changes between units of a given class. However, ship
construction, in contrast to major public works projects, is carried out in a dedicated industrial facility, the shipyard.
Meta-model
NATO Architecture
Framework
Technical Requests Rules
& Standards Environment
Budget Technology
Ship Concept Cost
Estimate Technology Plan
Models
Functional
Physical
(Digital
Mock-Up)
Behavioral
Probabilistic
NDMS
ASRU
EHCLS*
EHCLS*
Decoy launcher
DECOY'S
LAUNCHERS
Design Space
Mutli-physics
Simulation
Optimization
Strategy
Visualisation
Multi-objectives
Analysis
RESEARCH_2
57
Dedicated, but not specific, as the same facility, substantial and
capital-intensive, has to be usable for building ships of sometimes very different types and configurations.
Unlike other industrial sectors, where the effect of scale is
determining and each production line is specific, the production
process in shipbuilding is determined mainly by the infrastructure. Technological developments (use of high-performance
alloys and the introduction of composites, for example) and
international competition mean that the process needs to be
changed. The main objective is to improve the conditions under
which the operations are carried out, in order to increase productivity and reduce the rework rate. For example, the transition to construction in pre-outfitted blocks or sections in the
1980s was a major change in the industrial process of shipbuilding. The emergence of new areas of development for the shipbuilding industry, such as marine renewable energy, is also
demanding the development of new industrial approaches.
tools in real time.
A significant proportion of the construction costs is related to
manufacturing margins (stiffening, allowances), rework and
interruptions due to concurrent activity or to supply problems.
While significantly increasing productivity, the new production technologies will also make operations safer. The development of these innovative technologies is one of the major
objectives of DCNS Research.
The discussions now under way in various sectors on “the factory of the future”, focusing on robotisation, large-scale introduction of information technologies and the energy transition,
are also opening up new prospects of change for the shipbuilding industry. DCNS Research, with the IRT Jules Verne,
is involved in the various national and European initiatives
intended to develop the future production tools (advanced
manufacturing).
The future shipyard will be economical, with extensive use of
renewable energy, optimising its consumption in the context of
its energy distribution area. It will be clean, reducing its consumption of materials, thanks to lightening of structures, by
reducing the quantities of consumables needed for assemblies
and coatings and by recycling its own by-products and waste. It
will be safer, by automating and by moving all operations that
are difficult to carry out on board to open areas or workshops.
The future shipyard will be “digitised”, i.e. it will make full use
of all the power of IT resources to prepare the operations,
simulating the strains induced by welding or by handling
parts in order to better manage them, planning sequences in
advance and using haptic virtual reality (which reproduces
the forces) to optimise them and train the operators.
The future shipyard will be “informed”. Tracing and real-time
localisation of each part or equipment item thanks to the technologies of the “Internet of Things” (IoT) enables leaner flows,
reduced stocks and accurate and timely delivery, while optimising task start dates. This instantaneous knowledge of the
state of production is extended to all co-contractors (extended
yard). This information is available to the operators, who have
in situ access to the definition and production engineering
data using touch-screen tablets. Augmented reality will enable
operators to monitor the position and the settings of their
58
_REFERENCE
A. BOVIS: The Virtual Ship. 4th Conference on Complex Systems
Design and Management, Paris, 4-6 December 2013.
RESEARCH_2
RESEARCH_2
59
OUR SCIENTIFIC PUBLICATIONS
CONFERENCES – COMMUNICATIONS
_ “DYPIC project”
Artic Technology Conference 2014, Houston (United States),
Kerkeni et al.
_ N. Kamkar, F. Bridier, P. Bocher, P. Jedrzejowski
“Water droplet erosion mechanisms in rolled Ti-6Al-4V”
Int. Conference on Wear of Materials, Portland (United States),
14-18 April 2013
_ “Automatic heading control for DP in ice”
MTS DP Conference 2013, Houston (United States), Kerkeni et al.
_ “Capability plots of dynamic positioning in ice”
_ P. Bocher, D. Mingardi, B. Larregain, F. Bridier, F. Dughiero
“Simulation of fast induction surface heating and
comparison with experimental full-field surface
temperature measurements”
ASME OMAE Conference 2013, Nantes (France), Kerkeni et al.
Int. Conference on Heating by Electromagnetic Sources,
Padua (Italy), 21-24 May 2013
ASME OMAE Conference 2013, Nantes (France), Metrikin et al.
_ “Experimental and numerical investigation of dynamic
positioning in level ice”
_ “Comparison of control laws in open water and ice”
_ F. Bridier, J.-C. Stinville, N. Vanderesse, P. Villechaise, P. Bocher
“Measurement of microscopic strain localization and
crystal rotation within metallurgical grains”
Materials Structure & Micromechanics of Fracture, Brno (Czech
Republic), 1-3 July 2013
_ F. Bridier, J.-C. Stinville, N. Vanderesse, M. Lagacé, P. Bocher
“Measuring and comparing local strain field and crystal
rotation at the microscopic scale”
Microscopy & Microanalysis, Indianapolis (United States),
4-8 August 2013.
ASME OMAE Conference 2013, Nantes (France), Kerkeni et al.
_ Contribution J.-C. Poirier, DCNS Research/SIREHNA®
“Tank testing of a new concept of floating offshore wind
turbine”
Proceedings of the ASME 2013 32nd International Conference
on Ocean, Offshore and Arctic Engineering, OMAE 2013,
Nantes (France), 9-14 June 2013
_ “Comités scientifiques : modélisation et simulation
numérique du soudage”
11th AFM colloquium
_ M. Andriamisandrata, F. Bridier
“Insight on the mechanical behavior of copper bi-crystal
using crystal plasticity”
Materials Science & Technology Conference, Montreal (Canada),
27-31 October 2013
_ E. Liberge, M. Pomarède, E. Longatte, C. Leblond
“Réduction de modèle en interaction fluide structure
via une formulation POD multiphasique pour les
écoulements en faisceaux de tubes”
_ THERMEC 2013 conference
Las Vegas (United States), 2-6 December 2013
_ M. Allart, G. Rückert, P. Paillard
“Étude métallurgique du soudage par friction malaxage
sur un acier à haute limite élastique destiné à la
construction navale : le 80 HLES”
SF2M annual conference, Lille (France), 29-31 October 2013
11th Mechanical Engineering Congress, Agadir (Morocco),
23-26 April 2013
_ G. Rückert, M. Chargy, F. Cortial, F. Jorez
“Evaluation of FSW on high yield strength steels for
shipbuilding”
_ R. Fargère, P. Velex
“Some experimental and simulation results on
the dynamic behaviour of spur and helical geared
transmissions with hydrodynamic journal bearings”
THERMEC conference, Las Vegas (United States), 2-6 December 2013
5th VDI Wissensforum, München (Germany), 7-9 October 2013
_ C. Allery, A. Ammar, A. Dumon, A. Hamdouni, C. Leblond
“Proper generalized decomposition for the resolution
of incompressible flow”
Eccomas – 2nd International Workshop on Reduced Basis,
POD and PGD Model, Blois Castle (France), 3-6 November 2013
_ G. Rückert, N. Perry, S. Sire, S. Marya
“Enhanced weld penetrations in GTA welding with
activating fluxes – Case studies: plain carbon & stainless
steels, titanium and aluminum”
_ M. Allart, A. Benoit, P. Paillard, G. Rückert, M. Chargy
“Metallurgical Study of Friction Stir Welded High Strength
Steels for Shipbuilding”
_ S. Lakovlev, J.-F. Sigrist, C. Leblond, H. Santos,
C. T. Seaton, K. Williston
“Efficient semi-analytical methodology for the pre-design
analysis of the shock response of marine structures”
_ “DCNS experience about metal/composite assemblies
on board of navy ships”
ASME 2013, 32nd International Conference on Ocean, Offshore and
Arctic Engineering, Nantes (France), 9-14 June 2013
_ The 13th Euro-Japanese Symposium on Composite Materials
Nantes (France), 4-6 November 2013
OUR SCIENTIFIC PUBLICATIONS
_ “DCNS experience about composite patch onboard
of navy ships”
FP7-SST-2008-RTD-1 Sustainable Surface Transport,
European CO-PATCH project (Composite Patch Repair
for Marine and Civil Engineering Infrastructure Applications),
Stakeholder Workshop, London (United Kingdom), 17 April 2013
_ F. Cortial, T. Giraud, P. Recolin, S. Drobysz
“Soudage par faisceau d’électrons de l’acier inoxydable
austénitique stabilisé au niobium X6CrNiMoNb 17.12.2”
_ J.-C. Petiteau, E. Verron, R. Othman, P. Guéguan,
H. Le Sourne, J.-F. Sigrist, G. Barras
“Dynamic uniaxial extension of elastomers at constant
true strain rate”
Polymer Testing, vol. 32, p. 394-401, 2013
_ S. Lakovlev, C. Seaton, J.-F. Sigrist
“Submerged circular cylindrical shell subjected to two
consecutive shock waves: resonance-like phenomena”
Revue générale nucléaire, Ed. SFEN, 2013, no. 2, March-April, p. 70-75
Journal of Fluids and Structures, vol. 42, p. 70-87, 2013
_ G. Rückert, M. Chargy, F. Cortial, F. Jorez
“Evaluation of FSW on high yield strength steels for
shipbuilding”
_ Metrikin et al.
“Numerical simulation of dynamic positioning in ice”
MTS Journal, vol. 47, no. 2, March-April 2013, p. 14-30(17),
THERMEC conference, Las Vegas (United States), 2-6 December 2013,
Materials Science Forum, vol. 783-786, p. 1776-1781
_ X. Ledoux, F. Buy, A. Perron, E. Suzon, J. Farré, B. Marini,
T. Guilbert, P. Wident, G. Texier, V. Vignal, F. Cortial, P. Petit
“Kinetics of sigma phase precipitation in niobiumstabilized austenitic stainless steel and effect on the
mechanical properties”
THERMEC conference, Las Vegas (United States), 2-6 December 2013,
Materials Science Forum, vol. 783-786, p. 848-853
_ A. Pagès, J.-J. Maisonneuve, X. Dal Santo,
DCNS Research/SIREHNA®
“Étude et modélisation des petits navires de pêche pour
l’amélioration de leur comportement par mer forte”
ATMA 2014
_ D. Laneuville
“Polar versus cartesian velocity models
for manoeuvering target tracking with IMM”
_ J. Raymond (DCNS Research/SIREHNA®),
P.-M. Guillouet (DCNS)
“Bassin numérique et modèle libre générique : DCNS fait
évoluer son processus de conception hydrodynamique
des sous-marins”
IEEE Aerospace conference 2013
ATMA 2014
_ T. Millot
“Titanium in renewable energies DCNS’s OTECH issues”
_ C. Drouet, N. Cellier, J. Raymond, D. Martigny
OMAE 2013
“Sea state estimation based on ship motions
measurements and data fusion”
ITA 2013, International Titanium Association, Hamburg
(Germany)
PUBLICATIONS
_ N. Kamkar, F. Bridier, P. Bocher, P. Jedrzejowski
“Water droplet erosion mechanisms in rolled Ti-6Al-4V”
_ S. Kerkeni, X. Dal Santo, L. Vilain
DP Asia Conference
“Improved cost efficiency of DP operations by enhanced
thrust allocation strategy”
Wear, vol. 301, p. 442-448, 2013
_ B. Larregain, N. Vanderesse, F. Bridier, P. Bocher
“Method for accurate surface temperature
measurements during fast induction heating”
Journal of Materials Engineering and Performance, vol. 22,
p. 1907-1913, 2013
_ B. Chassignole (EDF R&D), P. Recolin (DCNS),
N. Leymarie (CEA), D. Elbaz (Extende), P. Guy (INSA Lyon),
G. Corneloup et C. Gueudre (Aix-Marseille universities)
BINDT
“3D modelling of ultrasonic testing
of austenitic welds”
_ R. Fargère, P. Velex
“Influence of clearances and thermal effects
on the dynamic behaviour of gear-hydrodynamic
journal bearing systems”
_ L. Rouleau, J.-F. Deü, A. Legay, F. Le Lay
“Application of Kramers-Kronig relations to timetemperature superposition for viscoelastic materials”
ASME, Journal of Vibration and Acoustics, 135(6), 061014-1, 2013
Mechanics of Materials, vol. 65, p. 66-75, 2013
TO LEARN MORE
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