Crash Absorption Structure for Formula Ford Use of ROHACELL in

Crash Absorption Structure for Formula Ford
Use of ROHACELL in Motorsport Crash
Worthiness
Bryan Chu
Oliver Jetson
Neal Parkhurst
Sébastien Pinauldt
Jorre Valeart
Cranfield University
MSc in Motorsport Engineering & Management
March 2007
Abstract
Build an economical frontal crash structure which may be used in the Formula Ford series. The
structure must meet three test conditions: a static crush test, a push off test, and a dynamic
sled impact. There are no limitations on the materials used in the construction of the crash
structure but the manufacturing costs must be kept under £400. The size limitations are as
determined by the regulations in the Formula Ford series.
Acknowledgements
There are many people who we would like to acknowledge for their support over the months for
this project.
Firstly we would like to thank Mr. Steve Wills, Mr. Keith Lain and the employees of Spirit
Racing Cars, for their guidance and use of facilities throughout.
Many thanks to Axel Zajonz from Degussa for providing the Rohacell material.
A special thanks to Mr. Jim Hurley and Dr. Denis Cartié from the Cranfield University
composites department for their advice and expertise with manufacture and testing.
For their support during the testing period we are greatful for the assistance of Robin Butler,
Tony, Clive, James and Ralph from the Cranfield Impact Centre.
We also acknowledge the help of Mrs. Kirsty Montgomery, Mr. John Nixon, Dr. Jeffrey Alcock,
Mr. Tony Lawrence and Mrs. Sharon Mcguire, all of Cranfield University.
Contents
1 Introduction
6
2 Objectives
7
3 Background Research
8
3.1
Driver safety within other formulae . . . . . . . . . . . . . . . . . . . . . . . . . .
8
3.2
Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
4 Design
9
4.1
Overall Design Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
4.2
Initial Evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
4.2.1
Energy and Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
4.2.2
FEA and PAMCRASH . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2.3
Initial Design Selection
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3
Aluminium Honeycomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4
Rohacell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5
4.4.1
Preliminary Performance Analysis . . . . . . . . . . . . . . . . . . . . . . 14
4.4.2
Analysis of Rohacell Crush Structure . . . . . . . . . . . . . . . . . . . . . 16
4.4.3
Adhesives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Secondary Bulkhead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.5.1
4.6
Analysis of Secondary Bulkhead . . . . . . . . . . . . . . . . . . . . . . . 22
Final Design
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1
4.6.1
Prototype Secondary Bulkhead . . . . . . . . . . . . . . . . . . . . . . . . 28
4.6.2
Final Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.6.3
Manufacturing Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5 Testing
5.1
5.2
34
Original Crash Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.1.1
Modifications Carried Out For Testing . . . . . . . . . . . . . . . . . . . . 34
5.1.2
Static Crush Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.1.3
Results of Testing Original Structure . . . . . . . . . . . . . . . . . . . . . 36
5.1.4
Conclusions Of Testing Original Structure . . . . . . . . . . . . . . . . . . 37
Final Design
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.2.1
Static Crush Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.2.2
Side Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.3
Front Impact Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6 Conclusion
51
A Secondary Materials
53
A.1 Skin Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
A.2 Core Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
B Preliminary Testing
57
B.1 Rohacell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
B.1.1 Static Crush Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
B.1.2 Impact Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
C Manufacturing Costs
61
2
List of Figures
4.1
Energy and Forces of Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2
Newton’s Second Law for an Average Acceleration . . . . . . . . . . . . . . . . . 10
4.3
Specific Energy Absorption of Rohacell . . . . . . . . . . . . . . . . . . . . . . . . 15
4.4
Compaction Percentage of Rohacell Grades . . . . . . . . . . . . . . . . . . . . . 15
4.5
Simplififed Rohacell Nose Cone Structure for FEA Optimisation . . . . . . . . . 17
4.6
Loading and Constraint Boundary Conditions for Rohacell Structure . . . . . . . 18
4.7
Rohacell Structure with a 20 mm lip Loaded at 30 kN . . . . . . . . . . . . . . . 19
4.8
Rohacell Structure with a 90 mm lip Loaded at 30 kN . . . . . . . . . . . . . . . 20
4.9
Rohacell Structure with a 115 mm lip Loaded at 30 kN . . . . . . . . . . . . . . 20
4.10 Rohacell Structure without side lips Loaded at 30 kN
. . . . . . . . . . . . . . . 21
4.11 Initial Design of Secondary Bulkhead before Optimisation . . . . . . . . . . . . . 23
4.12 Analysis of Initial Design: 1.5 mm wall thickness, 167kN distributed on top
plate,constrained at base of feet, and 5mm solid tetrahedral elements . . . . . . . 23
4.13 1 /4 Model with Symmetry Boundary Conditions . . . . . . . . . . . . . . . . . . 24
4.14 Analysis on Revision 1 Design of 1 /4 Model: 2 mm wall thickness, 167kN distributed on top plate, constrained at base of feet, 5mm solid tetrahedral elements 25
4.15 Analysis on Revision 2 Design of 1 /4 Model: 2 mm wall thickness, 167kN distributed on top plate, constrained at base of feet, 1.5mm solid tetrahedral elements 26
4.16 Localised Mesh Refinement at Edge of Triangular Braces . . . . . . . . . . . . . . 27
4.17 Analysis on Revision 3 Design of 1 /4 Model: 2.5 mm wall thickness, 167kN
distributed on top plate, constrained at base of feet, 1.5mm solid tetrahedral
elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.18 Prototype Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3
4.19 Final Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.1
Spirit Crush Structure Prepared for Testing . . . . . . . . . . . . . . . . . . . . . 34
5.2
Spirit Crush Structure Before Static Crush Test . . . . . . . . . . . . . . . . . . . 36
5.3
Spirit Crush Structure After Static Crush Test . . . . . . . . . . . . . . . . . . . 36
5.4
Original Spirit Crush Structure Static Load Test . . . . . . . . . . . . . . . . . . 37
5.5
Cracking of Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.6
Static Crush of First Full Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.7
Static Crush of Second Full Size Structure . . . . . . . . . . . . . . . . . . . . . . 40
5.8
Crushing of Scaled Down Model
5.9
Static Crush of 70% Scale Structure . . . . . . . . . . . . . . . . . . . . . . . . . 41
. . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.10 First Attempt at Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.11 Moments Before Structural Failure at a Load of 16.2kN . . . . . . . . . . . . . . 43
5.12 Remains of First Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.13 Second Attempt at Push Off Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.14 Top View of Crack in the Foam Structure During Second Push Off Test . . . . . 46
5.15 Placement of Pad in Third Push Off Test . . . . . . . . . . . . . . . . . . . . . . 46
5.16 Translation of Side Tabs in Push Off . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.17 Sled with Final Test Model Mounted . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.18 Resulting Data From Dynamic Test . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.19 Early Failure of the Material at 17 ms After Impact . . . . . . . . . . . . . . . . 50
5.20 Additional Loss of Material at the Base at 46 ms After Impact . . . . . . . . . . 50
B.1 Static Crush on a Sample of Rohacell 110IG, ø79 mm . . . . . . . . . . . . . . . 58
B.2 Drop Test on a Plain Sample of Rohacell 110IG, ø80 mm . . . . . . . . . . . . . 59
B.3 Drop Test on a Bonded Sample of Rohacell 110IG, ø76 mm . . . . . . . . . . . . 59
B.4 Collection of Rohacell Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4
List of Tables
4.1
Properties of Rohacell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2
Bill of Materials for Prototype Structure . . . . . . . . . . . . . . . . . . . . . . . 31
4.3
Bill of Materials for Final Structure . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.4
Total Cost to Produce a Prototype Structure . . . . . . . . . . . . . . . . . . . . 32
4.5
Total Cost to Produce a Final Structure . . . . . . . . . . . . . . . . . . . . . . . 33
4.6
Summarised Total Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.7
Volume Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
A.1 Properties of aluminium against other materials . . . . . . . . . . . . . . . . . . . 53
A.2 Properties of different glass fibre reinforcements against other fibre materials . . 54
A.3 Comparison of carbon fibre properties against steel . . . . . . . . . . . . . . . . . 55
A.4 Types of carbon fibre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
A.5 Properties of Kevlar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5
1 Introduction
Cranfield University in cooperation with Ford[12] and the governing bodies of motorsport,
namely the FIA[7] and the MSA[9], seek to develop the regulations of space frame chassis on a
worldwide level. In part to provide a set of standards for the safety of drivers in the numerous
Formula Ford series around the world, and additionally by creating a world recognised set of
regulations, Formula Ford can be introduced to new countries without the concern of creating
entirely new governing bodies. In the past there has not been any kind of common regulations
amongst the different Formula Ford series, and has been running in this method for a number
of decades.
The transition from the currently unregulated to a regulated state will not be an easy one
for Formula Ford to take on, and our part is only a small portion. This project will involve
examining the front crash structure used to protect the driver in the event of a frontal impact. At
the moment every manufacturer has a different method of producing their crash structure, and
none of these designs have been officially tested. Freedom is given to the student design groups
to develop a new crash box which will be tested against a set of impact requirements which
have been based off similar tests used for Formula 1 and Formula 3. The end result of these
new designs may be used as new structure which will be common amongst all manufacturers.
Ultimately the final product of the project should be a crash structure which can survive these
impact tests and be suitable for the low-budget mindset of the Formula Ford series.
6
2 Objectives
Produce a crash structure which will pass the following tests:
- Static Crush Test
- Side Push Off Test
- Front Impact Test
The hopes are that by performing these tests we can have a baseline as well as a comparison
between different designs which will lead to improved driver safety in a front impact situation.
Further details about the testing procedure are outlined in Section 5
The final construction costs of the crash box should not exceed £400 in keeping with the
spirit of the low cost racing series. In addition, we felt that majority of the structure, if not all
of it should be something that our manufacturer, Spirit, could produce in-house.
The groups will also have to generate a report which will detail the design, manufacture and
testing of the crash structure.
7
3 Background Research
3.1
Driver safety within other formulae
The greatest restriction to this project will be the limitation on the cost. The Formula Ford
series is structured as a low-cost series to permit the greatest number of entries. In comparison,
other series ranging from Formula 1 to Formula Renault typically use a carbon fibre monocoque,
have larger budgets, and already have a set of regulations to govern them. In following with
their carbon fibre monocoques their noses are essentially carbon fibre tubes made from sandwich
materials of nomex honeycomb. These differences enable the manufacturers and teams to use
more exotic materials and testing methods to ensure the crash structures will protect their
occupants. The goal is to bring this same level of safety to Formula Ford without causing strain
on team budgets.
3.2
Materials
There is a wide variety of materials that could have been used for building the crash structure.
The main materials which we focused on include aluminium honeycomb and polymer foams
which will be detail below. There was additional research into other materials listed in Appendix
A, these were gradually ruled out during our design selection process.
8
4 Design
4.1
Overall Design Requirements
In order pass these crash tests some basic goals must be achieved. The initial static crush test
will strictly be used to ensure that when the crash structure is attached to the dynamic sled that
it will absorb a sufficient amount of energy such that the testing equipment is not damaged.
The second test will be an important means of evaluating these newly developed crash
structures because the attachment points of the current nose boxes amongst all manufacturers
is seen as a severe weakness. In our research through examining past cars, speaking to teams
and manufacturers there has been a consensus that though the structures themselves may be
able to absorb some amount of energy in a crash there is a tendency for the nose section to be
easily detached before it has the opportunity to take part in the impact. That leaves us with
a critical issue of creating attachments which are strong enough to pass the specified push off
test, but also allow access and easy removal for servicing.
Finally the last test will be to determine if the new crash structure can absorb enough energy
in a dynamic test to slow the impact and limit the g-forces transmitted into the chassis. The
details of the mechanism for energy absorption are described below.
4.2
4.2.1
Initial Evaluations
Energy and Forces
During the crash, the kinetic energy is converted into a ”crush” work, the amount of work
energy put into a crushing load along the crush distance Lcrush .
Taking Vo as the initial speed provided by the testing regulation, and assuming the final
speed is zero we have ∆V = Vo . Also taking from the testing regulations we have a test mass
m. A straightforward energy calculation using the following equations, also demonstrated in
Figure 4.1:
1
· m · ∆V 2 = Ecrush
(4.1)
2
Ecrush = Wcrush = Lcrush · Fcrush
(4.2)
Where Ecrush is the energy to be absorbed by the structure, Wcrush is the amount of work done
on the structure, Lcrush is the length over which the crushing takes place, and Fcrush is the
forces performing the work.
9
Figure 4.1: Energy and Forces of Impact
During the crushing of the structure we have our Fcrush , from Newton’s Second Law and
using an average acceleration a we get:
Fcrush = m · a
(4.3)
Figure 4.2: Newton’s Second Law for an Average Acceleration
Since we have our prescribed mass of 595kg and maximum acceleration of 25g we can work
backwards to determine the forces involved and the required size of our structure. So from
Equation 4.3:
m
Fcrush = 595kg · 25 · g = 595kg · 25 · 9.81 2 = 146kN
(4.4)
s
If we take a margin on the value for maximum acceleration and choose 23g we have instead:
Fcrush = 595kg · 23 · g = 595kg · 23 · 9.81
m
= 134kN
s2
(4.5)
Moving on to Equation 4.1 and 4.2 we can solve for Lcrush giving the following:
Lcrush =
Ecrush
=
Fcrush
1
2
· m · ∆V 2
m·a
(4.6)
Using the calculations from above and our test velocity of 12 m/s:
Lcrush =
2
(12 m
s)
= 293mm
2 · 25 · g
(4.7)
Lcrush =
2
(12 m
s)
= 319mm
2 · 23 · g
(4.8)
10
So we see that in order to impact with a lower average acceleration from the same initial
velocity we will require a longer structure over which to absorb the energy in the impact. The
next stage is then to find a material which crushes at the forces calculated above and which
will fit within the length available within the current nose cone. Some of the materials we are
considering, such as honeycomb, have their characteristics listed as a load pressure, so we have
to relate our force to pressure via the cross sectional area of the structure.
Fcrush = Pcrush · S
(4.9)
Where Pcrush is tabulated in the manufacturer’s data sheets and S is the cross section of the
nose structure, similar to the length of the structure this area is governed by the dimensions of
the nose cone.
4.2.2
FEA and PAMCRASH
As with many current design processes there is a great desire to run simulations and virtual
tests before committing the resources to building and testing an actual product. We attempted
to do the same, to have a better understanding of how some of these potential materials may
behave under our test conditions. Finite Element Analysis (FEA) is commonly used, but it has
a limitation in this situation because it assumes a quasi-static equilibrium just the same as we
perform our static crush test and may not generate accurate results. The best case would be
to use a dynamic code such as those provided by PAMCRASH or LS-DYNA. We began some
training seminars to learn how to use PAMCRASH, but unfortunately the professor involved
in instructing us left the university shortly thereafter. In addition, students who had some
familiarity with the programs were also unavailable to help as they were all completing their
dissertations. So, due to the limited resources on hand we were never able to fully utilise these
program to evaluate our material selection. Instead we would have to rely on FEA and testing
samples of the materials and extrapolate the overall behaviour.
The accuracy of the results generated by any FEA software package is directly related to
the number of elements used for analysis, and this is also directly related to the calculation time
required for the analysis to converge to a solution. It is generally accepted that in the early
stages of a model’s analysis, a coarse element mesh can be used to generate fast results and
identify the effect of changes made, and that when the design is more finalised the mesh can be
refined, either in specific areas of interest or across the whole model to increase the calculation
accuracy.
Many software packages are available to carry out finite element analysis, either in the form
of dedicated FEA programs or in the form of FEA solvers within existing 3D CAD software. The
FEA software used for all analysis of the Secondary Bulkhead and the Rohacell Crush Structure
was the integral solver within the 3D CAD system I-Deas. This software was selected because it
allows detailed generation and inspection of the element mesh and also allows modification and
refinement of the mesh in areas of interest. The results of the individual components simulated
will be detailed in their respective sections.
4.2.3
Initial Design Selection
An initial collection of design options generated approximately 20 different choices. These
options are not necessarily exclusive of each other, but we needed some method of ranking
them to try to isolate them. We then created a list of requirements, our ”Musts”, for the design
11
which were typically governed by our regulations. The materials could not be affected by water,
our perception of the cost would have to be within the allotted £400, and it had to provide
sufficient energy absorption. Certainly our judgement of these options was not exhaustive and
rather subjective as we did not have the time or capacity to test and accurately evaluate all these
materials and designs. We used our best judgement to narrow our selection. After checking our
”Musts” the result was 12 options, so the next filter was to give them a ranking on how they
met some desirable traits, our ”Wants”. These traits included things such as how easily the
material can be worked into the required shape using standard tools or how readily available the
material might be. Again this is a rather subjective listing, but given our resources it seemed
to be a good starting point. The end result was a group of 5 choices which seemed to revolve
around the idea of utilising a skin made of aluminium to house a block of energy absorbing
material such as an aluminium honeycomb or foam placed on top of a secondary bulkhead to
allow for attachment to the chassis around the existing master cylinders and steering rack.
At the time of our initial analysis we had ruled out composites due to their difficulty of
manufacturing and in trying to keep to our philosophy of designing within Spirit’s production capabilities. However, this decision was made with our composite knowledge limited to
prepregs and autoclaves. After some more recent experience it seems that it may be possible
to use a vacuum infusion process to create composite structures without necessarily requiring
an autoclave.
4.3
Aluminium Honeycomb
Honeycomb materials are commonly used in sandwich structures and can provide a great deal
of strength in a relatively lightweight structure. However, there are a few design considerations
when working with the honeycomb. One factor is the resulting shape and orientation of the
individual cells within the core section of the material. As opposed with other bulk materials
such as with most metals and even with foams, their behaviour is generally isotropic whereas
honeycombs have a very defined directional strength. The strength of the honeycomb can be
tailored to a specific application by the choice of cell sizes as well as the cell wall thickness. This
results in a value for the overall density of the material, and when talking to manufacturers
they will reference their materials by this density as this will govern the cost of the material. So
we have determined that the strength of the honeycomb in the axial direction would work well
and could be adjusted to suit our needs, but this leads to concerns about the strength in the
other directions namely the lateral strength in order to withstand our side push off test. If we
plan on using the honeycomb it would have to be oriented longitudinally with the cells parallel
to the centerline of the chassis, and additional reinforcements would have to be incorporated to
support the lateral loads.
Another property of the material to be concerned with is how the cells compress. If we
consider a single tube under compression, there is a peak force which is required to initiate
the collapse of the remainder of the tube. This peak force causes a spike in the loading where
as the bulk of the tube under compression is a steady load. A similar issue applies to the
honeycomb structure where each cell has a high initial peak load before leveling off to a stable
crushing load. In addition to the problem of the spike, the side which begins the collapse can be
unpredictable which is an undesirable trait. The typical method of circumventing this problem
is to incorporate a pre-crush into the honeycomb by weaken and crushing a smaller percentage of
the cell on one side of the material. This pre-crush makes the compression behaviour much more
predictable and repeatable, unfortunately purchasing the honeycomb pre-crushed increases the
12
price.
In order to relate the specifications about the different grades of honeycomb we have to go
back to our initial calculations in Section 4.2.1 and decided on the surface area available to
use. As previously described it would be the internal dimensions of the nose cone as well as
the surface of the secondary bulkhead that governs the size of the structure. As a preliminary
design, we measured the internal dimensions of the nose cone and assumed an offset of 150 mm
from the main frame bulkhead to accommodate for the master cylinders and our secondary
bulkhead. This gave an average frontal cross sectional area of 0.030m2 for the space occupied
by the material. Using Equation 4.9 we determine with our 23g average acceleration that the
material must withstand a specific load of 4.5 MPa (650psi).
We contacted a few different aluminium honeycomb suppliers and manufacturers such as
Hexcel[8] and Plascore[10], and the appropriate range results in honeycomb cells either 1/8
or 3/16 of an inch across and a cell thickness of 0.002 in. or 0.0015 in. respectively. Upon
discussing the pricing we discovered that in order to get the correct amount to fill out structure
that the price for pre-crushed material was quickly approaching our £400 limit, and we had not
yet begun dealing with additional support for the lateral tests. The non-pre-crushed material
was more reasonable at about half the price, but this would incur additional labour costs if we
were to crush it ourselves for the best performance. However at the same time, research was
being done on other materials such as polymer foams and they were starting to show promise,
so we abandoned our option to build out of aluminium and focused on a polymer foam structure
instead.
4.4
Rohacell
As mentioned above we have investigated the use of polymer foams as our energy absorption
structure. Most of them are much too weak but this does not make them invalid because there
are a select few which are designed for high performance applications which we may be able to
use to our advantage.
One company, Degussa[6], sells a range of very high strength polymethacrylimide (PMI)
foams under the name Rohacell[11]. The Rohacell-WF range is available in a range of compressive strengths from 0.8 MPa all the way up to 15.8 MPa. As calculated above we are aiming for
a material whose compressive strength lies between 3.5 MPa and 5 MPa, so this range seemed
to fit well. The material itself has typically been used as a core material for producing composite sandwich structures and as such has never been fully tested for use as a bulk material in
this manner. However, after talking with a representative from Degussa it was suggested that
perhaps their IG series would be a better choice as it is still close to our required compressive
strength range and would be more economical.
The benefits of Rohacell is its homogenous cell structure and isotropic properties. The
biggest drawback is that because of its production process, its current form is only produced in
sheets. Various grades are available as various densities. We only focused on the lowest grade
(IG) as we do not require special properties in terms of heat resistance and resin processing,
which would utilise the higher grades. The material’s static behaviours are also favorable, it is
easy to cut with simple hand tools or can be placed in a mill. The manufacturer also suggests
thermoforming of parts, although that process is probably more suitable to larger production
volumes.
13
In terms of crushing, before performing any tests, the only known value was the compressive
strength, which we assumed to be identical to the steady crush strength. This was a large
assumption but considering the crushing mechanism of foam, it would make sense. A study
testing lower density foam confirmed that the behaviour is very steady until full compaction.
[13] During crushing a very clear plateau can be observed in the load vs. displacement curve.
The average load of the plateau corresponds well to the compressive strength value given in
the manufacturer’s datasheets. Further testing on samples of Rohacell demonstrated a similar
behaviour, see Appendix B.1 for our test results.
4.4.1
Preliminary Performance Analysis
In regards to the assumption explained previously, we specified a preliminary design in order to
pass the tests, similar to the preliminary design of the aluminium honeycomb structure, with
the required values of energy absorption, acceleration and side load.
The first parameter to evaluate is the energy absorption capability of the foam. Using the
compressive strength value (in MPa), keeping in mind our assumptions, we can calculate a
theoretical value for the Volumetric Energy Absorption (VEA) in kJ/m3 . If the compressive
strength is 3MPa for instance in the case of Rohacell 110IG, the theoretical VEA will be 3000
kJ/m3 for a block of 1 m3 . A more interesting value is the Specific Energy Absorption (SEA)
given by units of mass in kJ/kg which takes into account the foam density.
Density (kg/m3 )
Rohacell 31 IG
Rohacell 51 IG
Rohacell 71 IG
Test Samples
Rohacell 110 IG
32
52
75
96.5
110
Compressive
Strength (MPa)
0.4
0.9
1.5
2.36
3
Full
Compaction (%)
75
71.3
67
63
60
SEA (kJ/kg)
9.38
12.34
13.40
15.43
16.50
Table 4.1: Properties of Rohacell
There is a strong correlation between SEA with the density. We would then prefer the
highest grade, Rohacell 110IG. However, this advantage in terms of SEA might be balanced by
a greater remaining length after full compaction for the higher density materials, which is also
function of the density as seen in Figure 4.4.
Note that the figures of full compaction length are the result of a rough interpolation between
the results available for Rohacell 31 IG and our test samples.
In our case, we did not take into account the difference in the compaction length because
this difference is relatively small compared to the difference in SEA, and we would much prefer
to have the improved SEA at the sacrifice of some length. However this sacrifice is non-trivial,
the space available in the nosecone is a constraint especially having made the choice to use a
secondary bulkhead to fit the master cylinders, anti-roll bars and steering rack.
As seen previously from the hand calculation, the average acceleration value gives us a value
for the length over which the vehicle is going to stop. We will often refer to this length as
”crushing length”. The results gave a 293mm crushing length. Therefore the overall length
14
Figure 4.3: Specific Energy Absorption of Rohacell
Figure 4.4: Compaction Percentage of Rohacell Grades
should be 489mm considering 40% as the residual length after compaction. The actual model
will in fact be 500mm long which allows for some contingency in terms of acceleration.
15
However, after testing our samples we have found that the crushing loads that the material
can handle is slightly lower than expected. In order to compensate for this drop we decided
to make the volume of material larger than first predicted and as such the base surface area
of the secondary bulkhead is also increased over the initial assumed values although the length
remained the same as it was restricted by the nose cone.
4.4.2
Analysis of Rohacell Crush Structure
It is a requirement of the crush structure to withstand a side load of 30kN applied by a 100mm
x 300mm pad at a point 400mm from the front axle centre line. For this test requirement to be
met it was necessary to ensure that the Rohacell nose cone and its attachment to the secondary
bulkhead would not fail during this loading. As previously mentioned one of the benefits of
using Rohacell is its isotopic properties which could allow us sustain high off-axis loads. In this
following section we will try to evaluate the lateral performance through hand calculations and
FEA of the bare foam without any outer skin reinforcement.
The first criteria to be examined is the pressure being applied under the pad during the push
off test. With the tapered shape of our nose, the area under the pad is approximately 0.017 m2
and the load being applied is 30 kN which results in a pressure of 1.77 MPa. If we compare this
with the compressive strength of the foam of 3 MPa, it is clear that the pad pressure should
not be a problem.
The more critical criteria is the foam’s resistance to the bending moment being applied.
In order to get a basic sense of the result we kept the calculations simple, and used a beam
theory to determine the shear and normal stresses. It should be noted that the beam theory in
this particular case is outside its usual realm of application. The loads should be applied far
from the section of interest according to Saint Venant’s hypothesis, and the structure should
be highly elongated, preferably with a width-to-length ratio over 5, which is not the case in our
evaluation. However, this quick calculation was found to be the most straightforward way to
check our initial design. Without doing these calculations and starting from a FEA analysis
without any experimental data to compare with could have given highly unreliable results from
the start.
According to the beam theory, the highest value of normal stress will be located at the
furthest points away from the centerline. In our case that would suggest these normal stresses
lie along the outer edges away from the centerline of the bonded base. The shear also has to be
constant along the main axis, therefore we can use the Von Mises criterion, Equation 4.10 to
combine the effects of normal and shear stresses and compare with the maximum shear strength
of the material.
q
σ12 − σ1 σ2 + σ22 < σmaterial
(4.10)
In the case of our preliminary structure the calculated Von Mises maximum stress is 2.08 MPa
considering a 197 mm offset from the secondary bulkhead and the applied 30 kN, compared
to the shear strength of Rohacell 110 IG as 2.4 MPa. This gives us 15% contingency, which
unfortunately is not the biggest buffer but will have to suffice as this is the highest grade of
Rohacell in this series.
We can now use the hand calculations as a rough basis for our FEA. To carry out the FEA
16
on the side loading of the Rohacell crush structure a simplified model was constructed that
included the required 100mm x 300mm side push off pad.
Figure 4.5: Simplififed Rohacell Nose Cone Structure for FEA Optimisation
The side push off pad was included in the model on the assumption that as the pad was also
to be manufactured from Rohacell, during the side loading the push off pad and the nose cone
would effectively become one structure. This addition of the pad to the model file ensured that
accurate loading orientation would be achieved and that a simplified mesh could be generated
without the need for sectioning or a complex assembly file.
Another assumption for the generation of the FEA model was that the crush structure was
to be manufactured from one piece of Rohacell. This was not to be the case in the actual
manufacture of the component but as the shear strength of the adhesive used far exceeded the
shear strength of the Rohacell this was not considered for the analysis.
The final assumption was that an infinitely strong bond was achieved between the crush
structure and the secondary bulkhead. As the tensile and shear properties of the adhesive used
far exceeded the material properties of the Rohacell this assumption enabled the crush structure
to be constrained on the back face and meant that the secondary bulkhead did not need to be
included in the analysis.
For all FE calculations carried out on the Rohacell crush structure the following properties
were used, as taken from Rohacell.com; Young’s Modulus, E = 1.6 × 108 and Poisson’s Ratio,
ν = 0.38[11]. Initially, there were values supplied for Young’s Modulus and Shear Modulus, but
in using these to determine Poisson’s ratio it generated an unrealistic value of 0.6. It was found
that by using the supplied data for Young’s Modulus and Poisson’s ratio and allowing I-Deas
to solve for Shear Modulus, the analysis generated better results.
17
The loading and constraint boundary conditions that were used for all analysis was a distributed force of 30kN acting on the face of the push off pad and the rear face fully constrained
in translation and rotation. The constraint set imposed can be seen in Figure 4.6
Figure 4.6: Loading and Constraint Boundary Conditions for Rohacell Structure
It was suggested during the design of the secondary bulkhead that a lip could be positioned
around the perimeter of the top plate to provide additional surface area to bond to the Rohacell
foam. This was considered to be a good idea in terms of strength of tensile / compressive
attachment but the effect in side loading was not known so it was decided that a FE analysis
should be carried out on the effect of the lip size.
To represent the lips to be analysed, the CAD model was modified to provide a parallel
section at the base of the crush structure that was the height of the proposed fence. These
areas could then also be constrained in all translation and rotation to represent the bonding of
the foam to a steel side fence.
The first FE model that was generated with the additional 20mm bonding edge around the
perimeter is seen in the Figure 4.7.
It was determined from experimental testing that failure occurred at the join line between
the steel lip and the Rohacell foam. We now had some experimental data to use as a reference
to evaluate the validity of the FEA that was generated. We know from the manufacturer’s
datasheets that the maximum shear stress of the material is 2.4 MPa. By inputting the experimentally obtained force, which caused the structure to fail in two different test cases, into the
FEA simulation we found that there was an offset in the results of the FEA of approximately
2.4 MPa. Continued use of the FEA results would have to take this offset into account.
18
Figure 4.7: Rohacell Structure with a 20 mm lip Loaded at 30 kN
With this correction in mind we examined the FEA results seen in Figure 4.7, the peak
stress for the 20mm fence was 8.36MPa, now a corrected value of 5.96MPa, would not meet the
side push off requirements.
The analysis was also re-run with a larger side lip, it was originally suggested that increasing
the size of the side lip would increase the bonded area, reduce the moment experienced at the
top of the bond region and translate more of the load into shear giving an overall reduction in
stress at the point the steel fence joins the foam.
With the side lip size increased to 90mm it was found that peak stress at the foam/steel
joint line increased rather than decreased as had been hypothesised. The peak stress value from
the analysis was found to be 9.19MPa (Corrected: 6.79 MPa), as can be seen in Figure 4.8, an
increase from the 20mm fence model of 0.83MPa. This was an unexpected result as it had been
reasoned that the stress at the join line would decrease with lip height.
To confirm that the effect of increasing fence height resulted in increased peak stress the
analysis was re-run with a fence height of 115mm, Figure 4.9.
After the analysis with a fence height of 115mm was complete it was identified that the
peak stress at the join line had again risen and was now 9.34MPa (Corrected: 6.94 MPa).
This confirmed that the original hypothesis was incorrect and that minimum stress during side
loading would occur without side lips. To confirm that this theory was correct the model was
finally run with only the back face constrained to represent the model without bonded side
fences, Figure 4.10.
19
Figure 4.8: Rohacell Structure with a 90 mm lip Loaded at 30 kN
Figure 4.9: Rohacell Structure with a 115 mm lip Loaded at 30 kN
This final analysis confirmed two positive results. Firstly that the lowest peak stress during
the 30kN side push off loading would occur on the design without side fences and secondly that
the magnitude of stress at the foam/steel join line could be estimated as 5.5MPa (Corrected:
3.1 MPa), just above the limit of the Rohacell material.
20
Figure 4.10: Rohacell Structure without side lips Loaded at 30 kN
This suggested that the foam crush structure design could potentially pass the side push off
test if it was bonded on the back face only without the use of side lips.
4.4.3
Adhesives
The maximum thickness for the Rohacell material is limited to 75 mm, but because of our large
monolithic stucture we would require some method of keeping the pieces together so some for
of adhesive was also researched. In addition, to simply keeping the individual layers together
we also needed a relatively simple method of attaching the final block to our bulkhead without
significantly adding stress concentrations or incorporating incompressible components to the
foam and so it was decided that an adhesive would also be used for this attachment surface.
The requirements for the adhesive were ultimately that it must have excellent shear strength
while being easy to apply and cure at room temperature.
Several two part epoxies were investigated for use, namely those in the Araldite 2000 series
and Redux 600 series made by Huntsman Advanced Materials. These all have fairly good shear
strengths within the mid 20 MPa range at room temperature. However, there is one other
adhesive that surpassed these in terms of shear strength, Araldite 420A/B, also produced by
Huntsman. This adhesive has a shear strength up to 35 MPa at room temperature.[1]
Araldite 420 requires a 0.1 mm adhesive layer to achieve its optimum shear strength. A full
cure at room temperature is obtained in 7 days, but can be accelerated by heating at 50◦ C for
4 hours.
21
During production of our full size test pieces, we were unable to acquire a sufficient amount
of Araldite 420, so as a temporary substitute we used Scotch-Weld 7260 B/A from 3M[2]. This
adhesive was the closest match to the Araldite that was available to us, with shear strength
also in the mid-30 MPa. There was one surface which was bonded with this adhesive, and the
remaining model were still constructed with Araldite as there was an expedited shipment of the
required stock.
4.5
Secondary Bulkhead
The initial design requirement made little to no mention about the attachment of the crash
structure to the main chassis of the vehicle, and from Ford’s point of view as long as we
attached our structure to a flat plate of 300mm x 300mm, that would be sufficient. However,
we wanted to design something which could be attached to the vehicles if necessary so that
required additional considerations due to the space occupied by the steering rack and master
cylinders as these sit in front of the original bulkhead. Without these pieces attached to the
front we would have an excellent surface to work with, but realistically we had to find a way to
work around them.
From the onset we decided that the best way to solve this problem is to build out a second
bulkhead in front of the steering rack and the master cylinders both to protect these expensive
components as well as provide us with a flat surface to push against and then transmit residual
forces to the main chassis.
4.5.1
Analysis of Secondary Bulkhead
It was determined that the secondary bulkhead may have to withstand instantaneous peak
loads of 167kN during a worst case impact and so it was necessary to manufacture a structure
that would not fail during this loading. This peak load was determined from the assumed
compressive force of 3 MPa over an area of 196 mm x 280 mm, the updated base area for our
secondary bulkhead. The belief was that the Rohacell would be transmitting 3 MPa to the
back plate as it was being compressed, and this would be the forces the structure would have
to withstand.
As an initial design had been previously generated that met the geometric constraints of
avoiding the three master cylinders and providing a flat base for the crush structure to be
mounted on, it was then necessary to optimise this design to withstand the required input loads
using finite element methods.
It was identified that there were three major areas of optimisation for the secondary bulkhead
to enable the structure to withstand the required input loads. These were; the type of material
chosen for the bulkhead, the wall thickness of the material used and the addition of ribs and
braces to the structure to increase its strength.
It was decided early in the design stage of the secondary bulkhead that the component
should be constructed from steel rather than aluminium to reduce the time and skill required
for manufacture and to reduce material costs, therefore it was decided that the structure should
be made from a medium carbon steel with an approximate yield strength of 400MPa.
22
Figure 4.11: Initial Design of Secondary Bulkhead before Optimisation
For all FE calculations carried out on the secondary bulkhead the following generic steel
properties were used; Young’s Modulus, E = 2.068 × 108 ; Poisson’s Ratio, ν = 0.29; and Shear
Modulus, G = 8.0155 × 107 .
To identify what optimisation of the structure was required for it to withstand the calculated
worst case input loading of 167kN an FE Analysis was carried out on the initial design with a
proposed box section thickness of 1.5mm and a 3mm top plate.
Figure 4.12: Analysis of Initial Design: 1.5 mm wall thickness, 167kN distributed on top
plate,constrained at base of feet, and 5mm solid tetrahedral elements
23
As can be seen in Figure 4.12, the initial design did not meet the requirements for the
structure. At the side of the plot a colour contoured stress scale can be seen that ranges
between 0-400MPa. The contour range in this case has been set to the elastic range of the
material proposed for the construction of the component. It is particularly useful to set the
range in this way as it clearly identifies areas in black that have exceeded the upper limit and
have effectively yielded and therefore require some improvement. As can be seen in the previous
figure, black areas to represent material yield were found in all areas of the model frame and so
a wall thickness increase was proposed to 2mm.
It is also possible to display the FE plot so that it displays the calculated deformation of the
component, as can also be seen in Figure 4.12. This feature allows direct visual identification
of the areas of the component that may require additional stiffness in the form of braces or
ribs. It can clearly be seen that the 3mm thick top plate used to mount the crush structure has
deformed dramatically during loading. Since the plate was already 3mm it was decided that an
additional vertical cross brace at the centre of the span was a better option to stiffen the plate
rather than continuing to increase its thickness.
It was also observed that as the structure was effectively symmetric along two planes it was
possible to increase the analysis speed by imposing symmetry boundary constraints and hence
only analyse a quarter of the model, as seen in Figure 4.13. Symmetry boundary constraints
force the model to behave as if the whole model was still being loaded but as the effective model
size has been reduced, the number of elements required and the relative calculation time can
be reduced. It is also possible to increase the analysis accuracy by increasing the number of
elements and still retain a faster calculation time.
Figure 4.13: 1 /4 Model with Symmetry Boundary Conditions
24
Once the symmetric quarter model had been modelled, the box section frame wall thickness
was increased to 2mm and the central top plate brace was added. It was possible to run another
FE analysis to identify the effective of the proposed changes.
Figure 4.14: Analysis on Revision 1 Design of 1 /4 Model: 2 mm wall thickness, 167kN distributed
on top plate, constrained at base of feet, 5mm solid tetrahedral elements
As can be seen in Figure 4.14 (Stress Contour Range 0-400MPa), the proposed modifications
to the design were not sufficient to prevent material yielding across much of the component. To
reduce the deflection of the frame members and to increase the stiffness of the joint between the
frame members and the upright, triangulated braces were proposed to be manufactured from
the same box section material as the frame.
It was also observed that large deflections were still occurring in the top plate. The vertical
rib that had been added did have an effect on the deflection but the span between the inner
surface of the frame and the rib was simply too large to have fixed the problem completely. To
attempt to reduce the deflection further, an additional vertical rib was proposed so that a rib
would be positioned across the frame at one third and two thirds of the span.
It was suggested that the results may contain inaccuracies due to the coarse mesh used for
the analysis and more realistic results could be achieved with a finer mesh.
The proposed changes of triangulated corner brackets and additional / repositioned top plate
braces were modelled into the design in 3D CAD and then the analysis re-run with a mesh size
of 1.5mm to identify the effects of the changes made;
From the analysis of the revision 2 bulkhead in Figure 4.15, the proposed modifications
made a dramatic effect to the stresses acting on the component but they were not sufficient to
totally prevent material yield in all areas.
25
Figure 4.15: Analysis on Revision 2 Design of 1 /4 Model: 2 mm wall thickness, 167kN distributed
on top plate, constrained at base of feet, 1.5mm solid tetrahedral elements
It could be seen that the triangular braces at the joint between the frame members and the
upright had reduced the stresses in one of the members so that it was within the elastic range
of the material and had significantly reduced the stresses in the other. It was also observed that
the deflection of the top plate had reduced with the addition of the second brace so that the
majority of the plate was no longer yielding.
It was suggested that the high stresses observed at the point where the lower edge of the
two triangular plates met could be due to either a stress concentration in this area or because
of a calculation error caused by the tight geometry at the point. It was suggested that localised
mesh refinement would increase the accuracy of the results obtained in this region and the
surrounding area and enable the cause of the high stresses to be identified.
To further reduce the stresses acting on the frame and to attempt to ensure that all areas
were within the material’s elastic limit during worst case loading the wall thickness of the frame
box section was increased to 2.5mm for revision 3 and the analysis re-run with all additional
strengthening retained.
It can be seen in Figure 4.17 that even with the increase in frame wall thickness to 2.5mm
it was not possible to ensure that all areas of the secondary bulkhead structure were within the
material’s elastic limit during worst case loading. The increase in wall thickness had reduced
the stress in both the frame member and the upright considerably and so it was thought that
the required result of all components within elastic range could be achieved by further increase
in wall thickness.
26
Figure 4.16: Localised Mesh Refinement at Edge of Triangular Braces
Figure 4.17: Analysis on Revision 3 Design of 1 /4 Model: 2.5 mm wall thickness, 167kN distributed on top plate, constrained at base of feet, 1.5mm solid tetrahedral elements
However a consideration was made at this point that the component was becoming increasingly heavy and, as it was being designed for a light weight Formula Ford car, it could be that
27
the initial design requirement was unachievable without a considerably thick and heavy steel
structure that would be unsuitable for the intended purpose. It was decided that as a large
amount of the structure was within the material’s elastic limit of 400MPa and the majority of
the remaining structure was within the materials tensile limit of 600MPa the component would
be manufactured to this specification and hence the optimisation was complete.
4.6
Final Design
We have generated two designs which will be briefly described in terms of function and cost.
The prototype structure are the ones which we tested, though there are some small differences,
and the final design is the one which we are proposing with some potential improvements after
evaluating the results of our tests.
4.6.1
Prototype Secondary Bulkhead
Figure 4.18: Prototype Structure
As seen in Figure 4.18, the four box section steel legs of the secondary bulkhead act against
the face of the primary chassis bulkhead tubes and are attached to the primary bulkhead by
four bolts fitted through holes in the tabs on the ends of the secondary bulkhead legs.
The upper leg mountings consist of two tabs each that go either side of the primary chassis
tubes while the lower leg mountings consist of one tab each that rest against the outside of the
primary chassis tubes.
The upper bolts go through the upper tabs and chassis tubes (which have steel inserts welded
in to house the bolt shank) and require a nyloc nut to fix them in place. The lower bolts go
through the single tabs and screw into a threaded insert welded within the primary bulkhead
tube.
The four legs are welded to the box sections that make up the square front portion of the
secondary bulkhead with two triangulated reinforcement sections welded in on either side of
28
each leg to add strength. The legs come in at a small angle towards the tip of the nose so as to
allow the fitting of the bodywork (i.e. they protrude inwards).
The front portion has a flat steel plate welded to it to act as a reaction and bonding surface
for the Rohacell foam. The rear of this face plate is reinforced by two steel plate ribs welded
on. There is more plate welded around the edges of the front section so as to give a lip all the
way round providing a box for the cone to be located in and also to give extra area for bonding.
4.6.2
Final Structure
Figure 4.19: Final Structure
The structure in Figure 4.19 is very similar to the prototype version apart from the two
upper legs, which are shorter and act against the steering rack brackets as opposed to the
primary bulkhead itself. The upper legs only have one attachment tab through which a bolt
goes and screws into a threaded hole in each steering rack bracket.
This is done so that Spirit did not have to make significant changes to the design and location
of their current steering rack, but this does require small modifications to the current mounting
brackets.
Some key areas for improvement would be the following:
• a composite skin to improve the performance of the energy absorbing structure, we suggest
a 2 to 3 ply of woven fiberglass and polyester resin to keep production and material costs
down
• further optimise the secondary bulkhead the further strengthen the support and reduce
the overall weight of the structure
29
4.6.3
Manufacturing Costs
Assumptions for the Manufacturing Process
In order to cost the manufacture of the crash box, following assumptions have been made:
• The design is such that it can be manufactured at Spirit’s own facilities.
• The crash box will only require minor modifications to fit other manufacturers’ chassis.
• Standard costs for parts and materials have been used from Spirit’s suppliers and from
other external suppliers.
• The costs of any finishing processes have not been included.
• The cost of attaching the crash box to the car is not included but an estimate of time and
cost of assembling is included.
• Labour costs are based on Spirit’s hourly rate of £35.
• Machining costs are £6/hour, based on an average of universal machines.
• A 20% set-up allowance is added to every job. This covers the additional time needed to
set-up the machine, to clean it and for the additional adjustments to be made.
• Welding costs, drilling costs and sawing costs are based on the official SAE estimates.
(welding=£0.14/cm; sawing=5min/piece; drilling=3min/hole)
Schedule Of Materials
The materials used to construct Team Spirit’s frontal crash structures can be seen below in
Tables 4.2 and 4.3, also listed in Appendix C:
30
Table 4.2: Bill of Materials for Prototype Structure
Table 4.3: Bill of Materials for Final Structure
31
Full Manufacturing Costs
Tables 4.4 and 4.5 show the total cost to produce a single product, either of the prototype or
final structures. These tables are also listed in Appendix C.
Table 4.4: Total Cost to Produce a Prototype Structure
The cost of both designs are summarised in Table 4.6:
Mass Production
The breakdown for the production of 20 or 50 crash structures of the final design is listed
in Table 4.7
32
Table 4.5: Total Cost to Produce a Final Structure
Total Labour
Total Machine
Total BOM
TOTAL
Prototype Design
£140.35
£24.06
£163.35
£327.76
Final Production Design
£146.65
£25.14
£163.03
£334.83
Table 4.6: Summarised Total Costs
Total Labour
Total Machine
Total BOM
TOTAL
Quantity
1
20
£140.35 £2,925.00
£24.06
£502.80
£163.35 £3,260.80
£327.76 £6,688.60
Table 4.7: Volume Costs
33
50
£7,312.50
£1,257.00
£8,152.00
£16,721.50
5 Testing
5.1
Original Crash Structure
It was observed by the group that an easy solution to the design problem would be to either use
the existing design, if it met the performance regulations set, or to carry out some modifications
to the current design in order to increase its impact performance. In order to obtain some base
level crush performance data and also to identify if this was a possibility; a static crush test
was performed on a current production Spirit crush structure.
5.1.1
Modifications Carried Out For Testing
To enable the current production Spirit crush structure to be tested a number of modification
had to be carried out.
Figure 5.1: Spirit Crush Structure Prepared for Testing
34
The first consideration during test preparation was the representation of the chassis mounts
to the crush structure. It was observed that three options were available; to mount the crush
structure onto a car bulkhead, to connect the upper and lower mounts with a solid link or to
test the crush structure as a stand alone unit and not represent the mounts.
As the purpose of the test was to identify the performance of the crush structure and not
its relation to the chassis mounts it was decided that the unit should not be mounted to a
bulkhead. However, it was considered necessary for the mounts to be connected to stop the
unit separating unrealistically during testing so solid link representation was used. This was
created by using two lengths of M6 studding threaded through the mounts and locked at each
side by nuts secured either side of the honeycomb plate, as seen in figure 1 The use of M6
studding produced a solid link that was also compliant during high compressive loading.
Another test setup consideration was the modification of the crush structure to enable it to
be stable on the base plate during testing. A design feature of the Sprit crush structure is a
recessed section at the top of the unit to enable the integration of the crush structure around
the steering rack. The recessed area was squared off and then the remaining area was filled
by a 10mm steel plate and 40mm of dense wood. The combination of a steel plate and dense
wood was used to minimise compliance during compressive testing, however it was observed
that errors may be still be present in the results due to compression of the wood and also as a
result of stress concentrations at the corners as a result of the squaring off process.
5.1.2
Static Crush Test
For the test the crush structure was first placed onto the base plate of the compressive test
machine which was then raised until the front face of the crush structure was in contact with
the top plate. The static crush test programme was then started which raised the table by
a fixed displacement input of 30mm/min while monitoring the force required to produce this
displacement
During the test sequence a number of observations were made about the design of the current
Spirit crush structure and its ability to absorb the crush loading.
The structure is made up of a net of 5 aluminium honeycomb sheets that are held together
by steel angle plates riveted to the external skin of the aluminium honeycomb. During the
initial stages of loading the rivets that held the bottom honeycomb plate to the structure, seen
on the right of figure 2 were drawn through the side aluminium skins detaching it from the
main body. This resulted in bending of the lower front angle plate rather than compression
of the bottom honeycomb plate as it was not sufficiently restrained. The energy absorption of
the crush structure was therefore only based on the three remaining honeycomb plates. The
crush characteristic of the remaining structure was found to be reasonably effective. As can be
observed in figure 3 the top and side honeycomb plates and the side angle brackets displayed
highly uniform concertina buckling. This uniform crushing occurred up to the point of the
steering rack recessed area where the structure became solid and the test was stopped.
35
Figure 5.2: Spirit Crush Structure Before Static Crush Test
Figure 5.3: Spirit Crush Structure After Static Crush Test
5.1.3
Results of Testing Original Structure
To determine if the performance of the Spirit crush structure was acceptable under the new
regulations analysis of the results was carried out. As previously discussed in the Hand Calculations section of this report, section 4.2.1 for a crush structure to meet the criteria it must
36
have an average crush strength of 150kN and absorb 43kJ of energy over 300mm of deflection.
As shown in figures 5.4 below, it was found that the current Spirit design does not meet the
new regulations. In terms of crush strength the Spirit design displayed an average of 60.7kN
during static crush which is only 40% of the 150kN dynamic crush strength required to meet
the regulation. In terms of energy absorption the unit could only absorb 12kJ up to 200mm
deflection before the structure contacted the 10mm steel support plate and became solid. This
highlights two concerns with the current design; firstly, based on an extrapolated linear curve,
the unit can only absorb approximately 18kJ of energy over 300mm deflection which is only 42%
of the required 43kJ energy absorption and secondly the unit become solid before the required
300mm deflection to ensure a deceleration value of less than 25g.
Figure 5.4: Original Spirit Crush Structure Static Load Test
5.1.4
Conclusions Of Testing Original Structure
The testing of the Spirit crush box highlighted several important factors that will enable the
design process of the new crush structure to progress. Firstly it has confirmed that the current
design of riveted aluminium honeycomb plates will not meet the regulations and that if the
new design is to be based on a similar concept development must be carried out. The areas for
development could be the method in which the plates are joined, the selection of a higher energy
absorbing honeycomb plate or the filling of the internal volume with an absorbing material. It
has also shown that to meet the <25g deceleration criteria the steering rack must be moved or
the length of the crush structure must be increased.
It has also provided base level data in which to compare any subsequent prototype testing
should an alternative crush absorption method be used.
37
5.2
Final Design
The tests for each type are listed chronologically, but the individual tests may not have been
completed in the order below. In total there were three static tests, two full size and one scaled
down model. Three push off tests, all on full size models, and lastly a single dynamic test on a
full size structure.
5.2.1
Static Crush Test
This preliminary test will provide a baseline indication of the integrity of the design solution
and its ability to meet the requirements of the push off test and impact test by apply the
equivalent amount of energy from the dynamic test. However, because this test is performed in
a quasi-static equilibrium we will be less prone to causing damage to the equipment.
The test equipment has a limit of 200 mm of travel during testing and as our structure is
over double this length, the testing had to be done in a number stages where the structure is
released and the machine is reset to continue crushing. When the structure was released the
foam has a slight rebound, so when the data was recompiled each stage was stitched together
at matching load points.
First Static Crush Test
This first structure was based on our first prototype with a lip of 20 mm for the secondary bulkhead. This structure was then attached to our adapter plate which simulated Spirit’s chassis.
This structure had a total volume of 0.014 m3 which gives a theoretical energy absorption of
43 kJ and a mass of 1.58 kg. The Rohacell layers were bonded longitudinally to save on labour
costs as there are only two surface to bond but unfortunately this may have contributed to
some premature cracking and separation of material from the structure, as highlighted in red
of Figure 5.5.
Though there was some loss of material, the majority still managed to compress and absorb
a reasonable amount of energy, a total of 29.56 kJ with the average load of 73.97 kN. The
first thing to notice about this test, Figure 5.6, is that it is a significant improvement over the
original structure that we tested, Figure 5.4.
Second Static Crush Test
The second structure that was tested had the larger set of side lips for the secondary bulkhead,
115 mm in height, but the bonding direction was still the same as the first structure. The total
volume had increased slightly to 0.02 m3 to maintain the vertical profile along the sides of the
bulkhead lips. This additional material also increased the mass of the foam block to 2.21 kg.
As such the performance was similar, Figure 5.7, absorbing a total of 32.87 kJ of energy with
an average load of 88.28 kN.
38
Figure 5.5: Cracking of Structure
Figure 5.6: Static Crush of First Full Size
Third Static Crush Test
The final static test was performed on a small scaled down sample as a verification of the
performance if the Rohacell layers were bonded in a vertical orientation. Each dimension was
39
Figure 5.7: Static Crush of Second Full Size Structure
scaled down 70% resulting in a volume of approximately one third that of the full size model.
This smaller version absorbed 15.48 kJ at an average load 53.62 kN as seen in Figure 5.9 and
extrapolating the full size version as three times the volume we estimate that it would have
been able to absorb approximately 45 kJ. This is a 50% increase over what we had originally
tested with the bonding in the other direction. During the testing the material was much less
prone to separating off the sides as seen in the series Figure 5.8.
In our case, the structure obviously exhibits a much more complex behaviour. Two main
features of our design are supposed to be the cause: - adjunction of bond joints - tapered and
curved shape.
The difference between the theoretical and practical energy absorption values can firstly
been explained by the formation of numerous cracks across the structure. Those seem to have
two causes: - stress concentration around the bond joint - shear stress concentration due to the
local curvature.
40
(a)
(b)
(c)
Figure 5.8: Crushing of Scaled Down Model
Figure 5.9: Static Crush of 70% Scale Structure
41
5.2.2
Side Push Off Test
As defined from our original product brief:
To test the attachments of the frontal impact absorbing structure to the space
frame chassis, a static side load shall be placed on a vertical plane passing 400mm
in front of the front wheel axis.
A constant horizontal load of 30kN must be applied to one side of the crash
structure using a pad, 100mm long and 300mm high, with a maximum radius on all
edges of 3mm. The centre of area of the pad must pass through the plane mentioned
above and the mid point of the height of the structure at that section.
After 30 seconds of application, there must be no failure of the structure, or of
any attachment between the structure and the space frame chassis. During the test
the space frame chassis must be resting on a flat plate and secured to it solidly but
not in a way that could increase the strength of the attachments being tested.
First Side Push Off Test
For the first side push off test, the design tested was the bare Rohacell crush structure bonded
to the secondary bulkhead with an additional 20mm lip to increase the bonded area between
the steel structure and the foam.
A side push off pad that complied with the 100mm x 300mm requirement was produced
from the excess material that was removed during the nose manufacture to ensure that the
structure was loaded perpendicularly to the crush nose centre line.
A load cell was placed between the side loading jack and the push off pad to enable measurement of the load applied during the test and DTI’s were positioned opposite the load pad and at
the furthest forward point of the secondary bulkhead to measure the respective displacement.
The test setup for this first push off can be seen in Figure 5.10.
Results
The side push off test was to be carried out in two stages. Stage 1 being the progressive
increase in load applied to the structure from 0 to 30kN and stage 2 being the 30sec timed
period that the load must be maintained. During the stage 1 progressive loading the Rohacell
crush structure failed at a load of 20kN at the point of the join between the foam and the steel
fence.
Discussion & Conclusions
It was determined from hand calculations carried out before testing that the Rohacell material would be stressed below its failure range at the loading required by the side push off test.
However, as little test data was available for the materials properties in this situation it was
necessary to carry out the test to identify the materials characteristics.
From analysis of the failure surfaces of the Rohacell crush structure and the secondary
bulkhead, Figure 5.12, it was observed that the failure occurred initially at a point just above
one of the 20mm side lips and then propagated at a rough angle of 45◦ to the adhesive surface
on the top plate of the secondary bulkhead, where the material continued to separate just off
42
Figure 5.10: First Attempt at Push Off Test
Figure 5.11: Moments Before Structural Failure at a Load of 16.2kN
the surface of the adhesive. The good news about this test was that alleviated any worries
about the adhesive disbonding from the metal surface of the secondary bulkhead as all of the
adhesive remained intact. It was decided that an alternative design must be manufactured that
reduced the stress experienced at the foam / steel join line.
43
(a) Bulkhead
(b) Foam Block
Figure 5.12: Remains of First Push Off Test
Second Side Push Off Test
For the second side push off test, the design tested had the Rohacell crush structure bonded to
the secondary bulkhead with a larger 115mm lip to further increase the bonded area between the
steel structure and the foam. In addition to the greater area, it was proposed that an increased
side lip height would reduce the moment at the point and thus reduce the tensile stress on the
material but increasing the shear loading.
As the cross section at the point of loading was the same as in the previous test the same
side push off pad was used as test 1.
Again the load cell was installed between the side loading jack and the push off pad to
enable measurement of the load applied during the test and DTI’s were positioned opposite to
the load pad to measure the displacement.
Results
It was expected that the increase in lip height would reduce the tensile stress at the join
line and hence increase the maximum achievable side load force, however this was not the case.
During the progressive loading, the Rohacell crush structure failed at a lower load of 16kN
also at the point of the join between the foam and the steel lip, but now further up the structure.
Discussion & Conclusions
The second side push off design was generated in haste as a product of failing the first side
push off test. The modifications made to the original design were determined by discussion and
basic calculations, not reasoned analysis as they should have been. This resulted in a design
that was worse than the original.
From analysis of the failure surfaces, Figure 5.14, it was again observed that the failure
occurred at the point just above the top of the one lip. The failure then propagated across the
width of the structure as the Rohacell material progressively failed.
44
Figure 5.13: Second Attempt at Push Off Test
It was decided that a further FE analysis should be carried out on the side push off load
case as described in Section 4.4.2 to attempt to fully understand the cause of the early failure
during the second test.
Third Side Push Off Test
It was determined, from the FE analysis carried out on the side push off, that the lowest stress
occurred in the model without the side lips, however the FE results achieved were still too close
to the failure range of the Rohacell material and so it was considered too risky to carry out
another test that had a possibility of failure.
Instead it was decided that the side push off test should be carried out by positioning the
side push off pad on the 115mm side lip at a point 100mm closer to the wheel centerline rather
then directly on to the Rohacell nose as seen in Figure 5.15. It was determined by calculation
that the steel secondary bulkhead would be able to easily withstand the loading required and
would enable the design to pass the side push off test stage. This test procedure was validated
by the fact that the regulations state that the load ’must be applied to one side of the nose cone
(containing the nose crash box structure)’.
Results
As had previously been calculated, the structure was able to withstand the 30kN when
the side push off loading was applied to the fences of the secondary bulkhead and was able to
45
Figure 5.14: Top View of Crack in the Foam Structure During Second Push Off Test
Figure 5.15: Placement of Pad in Third Push Off Test
46
maintain the load for the required 30secs. Based on the previously discussed assumption this
was considered a test pass. However, it has to be noted that the lateral attachment brackets
of the second bulkhead bent and this resulted in a 2 mm permanent lateral translation of the
crash structure as seen in Figure 5.16. It has to be said that this should not interfere with the
dynamic crash behaviour of the whole structure as during the crash, the majority of the load is
transmitted longitudinally to the front bulkhead of the chassis. These brackets were made out
of 3mm thick mild steel. They could be made thicker or out higher grade steel, but we decided
to keep this same design for the final version for both weight and cost concerns considering that
this would neither affect the integrity of the structure nor the crash worthiness.
Figure 5.16: Translation of Side Tabs in Push Off
Discussion & Conclusions
As previously discussed the method of passing the side push off test by pushing on the steel
side fences was not the original design intention but can still be considered a validation of the
design.
The side loading of the crush structure was still carried out on a position that was predominantly made up of energy absorbing material and the assumed distance from the car front axle
centre line was made on the basis that this value could be changed for the ’08 car if required. If
the assumed value was not considered valid it could also be possible to further extend the side
fences and include them as part of the crush structure to enable the test to be carried out at
a point 400mm from the existing car centre line, rather than the 300mm for this final push off
test.
47
5.2.3
Front Impact Test
As defined from our original design brief:
For the purposes of this test, the total weight of the trolley and test structure
shall be 595kg and the velocity of impact 12 m
s The space frame chassis and nose
assembly shall be subjected to an impact test against a solid vertical barrier placed
at right angles to the centre line of the car. The resistance of the test structure
must be such that during the impact the average deceleration of the trolley does not
exceed 25g. The chassis must not suffer damage as a result of the above test.
However, for the final test setup we used a sled with a mass of 660 kg and ran at a slower
speed to obtain an equivalent energy. An image of the setup can be see below:
Figure 5.17: Sled with Final Test Model Mounted
This last structure which we tested is built similarly to the first structure used in the static
tests, except that the bond direction is vertical as was tested in the third static test, Section
5.2.1. The total volume for this structure is 0.0192 m3 and a mass of 2.11 kg and therefore its
estimated energy absorption is 53kJ, although we have to keep in mind that the static test on
the scaled structure estimated an energy absorption of 45kJ.
The test speed was 11.41m/s and the data shows that a mean g over the course of the impact
was 16.25g. The design requirement was to have an overall average g less than 25g, which is
clearly obtained by a margin of 8.75g.
The mean g for the first 150mm of crush was 7.35, peaking at 11.61g. Once the crush length
reached the region of 190mm, the acceleration had peaked at 13.12g in a time of between 17 and
18ms. The acceleration is then seen to drop off over the next 15ms to 6.72g until a crush length
48
Figure 5.18: Resulting Data From Dynamic Test
of 330mm is reached and the sled has been slowed to 8.41m/s. This drop off in acceleration is
due to a crack propagating on the top and bottom surfaces seen in Figure 5.19, leading to less
of a deceleration because the material is giving way without compressing meaning there is not
as much material available to resist the impact.
During the next 37ms (total time of 70ms) the acceleration rises to a test highest peak of
41.33g and the sled has been slowed to 0.7m/s with a crush distance totalling 536mm. The
increase in acceleration up to 41.33g can be accounted for by the breaking up of the nose into
large pieces resulting in the metal secondary bulkhead taking the load and having to deform
giving a more severe deceleration, see Figure 5.20 Zero velocity is reached after a total crush
time of 71.45ms and a total crush length of 537mm.
The concluding points to the dynamic test are that there was a very good initial crush for
the first 190mm where the material broke up into small bits. However when the nose cone then
started to break up in to large pieces the energy was not well absorbed and the sled did not
slow as quickly or controlled as we had hoped. This could be overcome by making the entirety
of the crush work as it did within the first 190mm with all material being destroyed or crushed
into small pieces. This could be achieved by enclosing the foam structure within an outer skin
made of composites such as GRP, carbon fibre, or possibly even aluminium.
49
Figure 5.19: Early Failure of the Material at 17 ms After Impact
Figure 5.20: Additional Loss of Material at the Base at 46 ms After Impact
50
6 Conclusion
We have demonstrated the crash worthiness of a very innovative material. The use of Degussa’s
Rohacell high density polymer foams is definitely recommended for motorsport crash applications and especially in the low cost environment of Formula Ford. The Rohacell foam exhibits
the following upsides:
• homogenous structure
• isotropic properties and therefore good off-axis loading tolerance
• high Specific Energy Absorption
• very easy manufacturing well adapted for small manufacturers
After numerous physical tests and calculation, we have specified a design for Spirit Racing
Cars’ Formula Ford chassis integrating such an absorbing structure. This design increases
significantly the safety standards of the car and passes all the test requirements specified at the
beginning of the project. The absorbing structures structure itself only weighs 2.1 kg without
skinning and 3.3 kg with a composite skin to improve the performance as well as provide day-today protection. This normally comes with a removable frontal chassis extension which weighs
3.1kg in its latest revision. Compared to the original aluminium sandwich panel design, the
absorbing core material almost absorbs four times as much energy for a similar weight and
the manufacturing cost of the absorbing material alone is even lower. The version without
composite skin costs £334 including the chassis extension which is 15% under the initial cost
target.
The definite advantages of our solution are:
• very good energy absorption figures
• very reasonable weight
• safety for other competitors (especially in case of side impact)
• low manufacturing cost
• manufacturing simplicity
51
Bibliography
[1] Huntsman advanced materials - araldite 420 a/b.
[2] www.3m.com/bonding.
[3] www.aluminium.matter.org.
[4] www.azom.com.
[5] www.chm.bris.ac.uk/webprojects2002/mjames/chemistry.html.
[6] www.degussa.com.
[7] www.fia.com.
[8] www.hexcel.com.
[9] www.msauk.org.
[10] www.plascore.com.
[11] www.rohacell.com.
[12] www.ukformulaford.co.uk.
[13] Rickard Juntikka. Rohacell 31 ig - crash behaviour. Technical report, KTH Aeronautical
and Vehicle Engineering.
[14] K. Tucker, N.; Lindsey. An introduction to automotive composites. Technical report, Rapra
Technology Shawbury, 2002.
[15] Marino Xanthos. Functional fillers for plastics, 2005.
52
A Secondary Materials
Some materials relevant to the initial crash box design ideas have been looked at for initial
evaluation. They can be broken down into two main sections namely skin materials and core
materials.
A.1
Skin Materials
Aluminium
Pure aluminium is soft and malleable and must be alloyed with other elements such as
zinc, copper, magnesium, silicon, lithium and manganese for higher strength applications such
as automotive structures. Aluminium alloys have excellent corrosion resistance and strengthg
to-weight ratios (see Table A.1) due to it having a density of only 2.7 cm
3 , one third that of
steel.
Properties: They are very versatile alloy materials primarily because of the ability to form
them into complex structural shapes, without the need of addition of additives.
Property
Tensile strength (MPa)
Elastic modulus (GPa)
Elongation to break (%)
g
Density ( cm
3)
Relative cost
S-Glass
4600
85
3.5
2.5
3.8+
Carbon
3800-6530
230-400
1.4
1.8
52-285
Steel
200-1880
190-210
10-32
7.85
1
Aluminium
230-570
70-79
10-25
2.7
3
Table A.1: Properties of aluminium against other materials
[3][4]
Types and Applications: Aluminium sheet thicknesses are classified by gauge and the alloying additions are classified by different numbered series from 1xxx to 8xxx, where the ”xxx”
specifies a particular manufacturing process for that series.
6xxx and 7xxx series alloys are used for aluminium bumpers because of their high strength.
Age-hardened 6xxx series alloys are used as body closures such as bonnets, roofs and door
panels because of good formability, dent resistance, corrosion resistance and surface appearance.
Aluminium structural components use precipitate hardened 6xxx series alloys to achieve the high
strength and stiffness requirements.
53
Aluminium also has better energy absorption properties than steel in crash situations. An
aluminium crush can is as effective as a steel crush can but only weighs half the amount.
Glass Reinforced Plastic (GRP)
The two most common components used to produce a GRP are polyester and E-glass fibres.
Alternatives to polyester include vinylesters and epoxies while S-glass and C-glass fibres can
also be used as reinforcements for different applications. The properties of GRP are greatly
dependent on the type of fibre used, the orientation of that fibre and the proportion used in the
mix.[14]
Property
Tensile strength (MPa)
Elastic modulus (MPa)
Elongation to break (%)
g
Density ( cm
3)
Relative cost
E-Glass
3450
73
3.5
2.58
3.7
S-Glass
4600
85
3.5
2.5
3.8+
Carbon
3800-6530
230-400
1.4
1.8
52-285
Aramid (Kevlar 49)
3600-4100
131
2.5
1.44
44
Table A.2: Properties of different glass fibre reinforcements against other fibre materials
• Low cost
• High production rates
• High strength
• High stiffness
• Relatively low density
• Non-flammable
• Resistant to heat
• Good chemical resistance
• Relatively insensitive to moisture
• Maintains strength over a wide range of conditions
• Good electrical insulation
Carbon Fibre
The current level of carbon fibre technology can produce amazingly strong components with
the least amount of weight, however they do still have their drawbacks. They are relatively
expensive and a recent global shortage in carbon fibre means that prices are higher.
Properties: The mechanical properties of carbon fibre are dominated by the fibres used and
the fibre architecture as stated above. The ultimate strength and weight of a component is also
dependent on the skill with which the laminate is designed and manufactured. Performance
is significantly compromised by dry fibres, air pockets and gaps between plies. Consequently
54
Property
Tensile Strength (GPa)
Tensile Modulus (GPa)
Specific Density
Specific Strength
Average Grade Carbon Fibre
3.50
230.00
1.75
2.00
High Tensile Steel
1.30
210.00
7.87
0.17
Table A.3: Comparison of carbon fibre properties against steel
[15]
the properties presented in Table 3 and Table 4 are general and may differ depending on the
manufacturer.
As can be seen, carbon fibre has a tensile strength almost 3 times greater than that of steel,
yet is 4.5 times less dense.
There are many different grades of carbon fibre available, with differing properties, which
can be used for specific applications.
Type
High Tenacity
Ultra High Tenacity
Intermediate Modulus
High Modulus
Ultra High Modulus
High Modulus/Tenacity
Tensile Strength (GPa)
4.0
4.8
6.0
3.5
3.4
3.9
Tensile Modulus (GPa)
240
240
290
375
425
400
Table A.4: Types of carbon fibre
[5]
Other desirable physical properties of carbon fibre and other composites include its resistance
to corrosion, fire and high stress tolerance levels as well as its chemical inertness. The beauty of
carbon fibre is that it can be fabricated in such a way that directional performance (in terms of
response to force applied) can be manipulated to give the best possible results in virtually every
circumstance. The ability to arrange fibres to suit the particular forces affecting a component
mean more areas of weakness can be eliminated.
Kevlar
Kevlar is the registered trade name of a type of aramid that consists of long polymeric chains
with a parallel orientation made by DuPont. Kevlar obtains its strength from intermolecular
bonds and stacking interactions between aromatic groups in neighbouring strands. Kevlar
consists of quite rigid molecules, which form a planar sheet-like structure similar to silk. It
gives excellent resistance to piercing. Kevlar’s main weaknesses are that it degrades in alkaline
conditions or when exposed to chlorine. While it can have a great tensile strength, sometimes
in excess of 4000 MPa, like all fibres it tends to buckle in compression.
Manufacturing: Kevlar can be bought in pre-woven fabric matts just like carbon fibre. The
layup process for Kevlar follows exactly that of carbon fibre whether using a wet layup or
pre-impregnated fibres.
55
In structural applications, namely body panels, Kevlar fibres can be bonded to one another
or to other materials to form a composite material. It can be used together with carbon fibres
in a hybrid weave in which carbon fibres are in one direction of weave and Kevlar is woven in
the other direction. This allows the properties of both carbon and Kevlar fibres to be utilised.
Property
Density (g/cm3 )
Breaking Tenacity (MPa)
Tensile Modulus (MPa)
Tensile Strength - epoxy impregnated strands (MPa)
Tensile Modulus - epoxy impregnated strands (MPa)
Kevlar 29
1.44
2920
70500
3600
83000
Kevlar 49
1.44
3000
112400
3600
124000
Table A.5: Properties of Kevlar
From the table, in comparison to some of the other materials, Kevlar has some great benefits
for structural applications. However, it can be difficult to work with and requires special cutting
tools due to its high toughness.
A.2
Core Materials
Woods
Balsa is the most common wood core having first been used in early plane design sandwiched
between sheets of aluminium. It has high compressive strength but suffers as a solution to race
car design due to its high density (> 100 kg/m3 ).
Honeycomb[8]
Aluminium honeycomb comes in at around the same cost (base level version) as the above
mentioned foam however its properties are considerably better. It has the greatest strength per
unit weight of all honeycombs, and provides excellent energy absorbing properties particularly
relevant to vehicular crash safety.
The most common cell structure of honeycomb is a regular hexagonal shape with cell sizes
ranging from 1/8” up to 3/8” and cell wall thicknesses of between 0.0007” and 0.006”. Depending on wall/cell sizes the density is usually less than 100 kg/m3 .
Typical aluminium alloys used for the honeycombs are 5052, 5056 and a few lower cost 3000
series alloys. The 5000 series alloys are aerospace grade, the difference between 5052 and 5056
being 5056 gives around 20% higher strength than 5052, but comes at a higher premium. 3000
series are lower in cost still.
Aramid honeycombs are effectively paper that has been dipped in phenolic resin leading to
very high strength, excellent flame resistance but the cost is usually more than twice that of
aluminium honeycomb and aluminium is stiffer.
Common aramid honeycombs are Nomex and Kevlar, with densities mostly less than aluminium derivatives.
56
B Preliminary Testing
B.1
Rohacell
We were not able to get extensive test data from Rohacell as their material has never been
used in this particular type of application. Along with the lack of simulation data we needed
to perform tests on material samples in order to get an idea of how this material may work
in our crash structure. Similarly to our test of the original crash structure, we performed a
static crush test on a plain cylindrical sample. In addition, we performed a dynamic test on
a plain sample using a drop tower and due to our layered and bonded design we decided to
perform an additional dynamic crush test to evaluate the effects of a layer of Araldite 420
epoxy approximately 1mm thick down the center of the sample. This epoxy cures at room
temperature, but the sample was given a slight heat treatment to speed the curing process, this
should have an insignificant effect on the final strength of the bond or the foam.
B.1.1
Static Crush Test
This test was performed in a hydraulic press and placed under a constant displacement of 5mm
per minute and the load was recorded as a function of the displacement. The diameter of the
cylinder was 80mm and the height was 75mm.
It would be interesting to overlay the manufacturer’s compressive strength value on top of
the data obtained as a reference, but that information was unavailable. We were hoping to get
samples of Rohacell 110 IG to test as that was the material which we were planning on using for
our structure, but instead it was a slightly lower grade which they do not sell commercially and
we had relate these results to Degussa’s datasheets. We can reasonably estimate the compressive
strength at the beginning of the crushing plateau, which gives us a value for σc = 2.44 M P a,
whereas the manufacturer lists it as σc = 3.0 M P a. In the end the results correlated well with
our potential material choice.
The material exhibits a steady behaviour until it reaches full densification at 51mm, approximately 32% of the initial value. Prior to reaching full densification, 637 J have been absorbed
kJ
which is equivalent to 15.75 m
3 , corresponding to an average engineering stress of 2.53 MPa.
For our application, it is also important to note that the material remains intact as a
single block and there is no obvious failure, the energy seems to be only absorbed through the
compaction of the foam.
57
(a) Energy and Stress
(b) Compacted Sample
Figure B.1: Static Crush on a Sample of Rohacell 110IG, ø79 mm
B.1.2
Impact Test
The two following impact tests were performed in a drop tower with a mass of 40 kg and a
velocity of 7 m
s which result in a total energy of 1 kJ.
The plain sample behaved similarly to the static test, other than some pieces which fragmented of the sides. However, this could be due to additional energy applied after reaching full
compaction of the material when it was become more brittle. The total energy absorbed by
kJ
this sample is less than the static test with a value of 512 J (12.3 m
3 ), resulting in an average
engineering stress of 2.21 MPa. The final length of the sample is 37% of the original sample.
The second bonded sample also behaved very much like the first, expect for some cracks
which initiated at the bond layer. Again it is hard to determine if this happened before or after
reaching the fully compacted length. The total energy absorbed in this sample is slightly lower
kJ
at 481 J (12.8 m
3 ), but because the sample size is slightly smaller in diameter, 76 mm vs 80 mm
for the plain sample, it has an average engineering stress of 2.30 MPa. The resulting length
after this impact is 38%, very similar to the first impact test.
Overall, we see a bit of a drop in energy absorption when it came time to the dynamic tests
but the material still fared well and gave linear and stable results. There was some failure of
the material but it was mainly restricted to the periphery and may have only occurred after
reaching full compaction. The bond line in the second sample which was originally a possible
source of weakness has been proven to withstand the impact and not have a significant effect
on the energy absorbed in the compression.
58
(a) Energy and Stress
(b) Compacted Sample
Figure B.2: Drop Test on a Plain Sample of Rohacell 110IG, ø80 mm
(a) Energy and Stress
(b) Compacted Sample
Figure B.3: Drop Test on a Bonded Sample of Rohacell 110IG, ø76 mm
59
Figure B.4: Collection of Rohacell Samples
60
C Manufacturing Costs
61
Bill of Material
Formula Ford Spirit
Part
Sub Assembly
Prototype
Crash Box
Bill Of Material
Part No
FFS-10
FFS-10
FFS-21
FFS-22
FFS-231
FFS-232
FFS-24
FFS-25
FFS-26
FFS-27
FFS-28
FFS-30
FFS-31
FFS-32
FFS-30
Description
Rohacell 110 IG (75mm)
Araldite 420
Mild steel tube (25x25x2,5)
Mild steel tube (25x25x2,5)
Mild steel tube (25x25x3)
Mild steel tube (25x25x3)
mild steel plate 280mmx200mmx3mm
mild steel plate 300mmx25mx3mm
mild steel plate 310mmx20mmx3mm
mild steel plate 393mmx135mmx1,5mm
mild steel plate 560mmx135mmx1,5mm
Allen Bolt M6x35
Nut M6
Washer M6
Allen Bolt M6x20
Unit Price
No requ'd
£279/m²
0,5 m²
£68,25/kg
200g
£2,65/m
960mm
£2,65/m
415mm
£2,65/m
200mm
£2,65/m
200mm
£20,68/m²
0,056m²
£20,68/m²
0,0075m²
£20,68/m²
0,0062m²
£20,68/m²
0,053m²
£20,68/m²
0,0756m²
£0,26
2
£0,06
2
£0,06
4
£0,26
2
TOTAL Bill of materials
Comments
Signed
Team Spirit
Date
19.3.07
Delivery Total Cost
Degussa
£139,50
£13,65
£2,54
£1,10
£0,53
£0,53
£1,16
£0,15
£0,13
£1,10
£1,56
1 day
£0,52
1 day
£0,12
1 day
£0,24
1 day
£0,52
£163,35
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Prototype
Crash Box
Bill Of Material
Part No
FFS-10
Description
Rohacell Nose Cone
FFS-20
FFS-21
FFS-22
FFS-231
FFS-232
FFS-24
FFS-25
FFS-26
FFS-27
FFS-28
2nd Bulkhead
Frame
Tubes
Internal Reinforcement triangels
Lateral Reinforcement triangels
Front Plate
Reinforcement Plates
Attachment Brackets
Side Fence
Top Fence
FFS-30
FFS-31
FFS-32
FFS-30
Allen Bolt M6x35
Nut M6
Washer M6
Allen Bolt M6x20
Unit Price
£0,26
£0,06
£0,06
£0,26
No requ'd
1
1
1
4
8
8
1
2
6
2
2
internal
internal
internal
internal
internal
internal
internal
internal
internal
internal
2
2
4
2
1 day
1 day
1 day
1 day
Total Labour time (min)
Total £ Labour
Total £ Machine
TOTAL for Proto Crash Box
Comments
Signed
Team Spirit
Date
19.3.07
Delivery
Rohacell
Total Cost
£199,07
£43,05
£22,63
£9,30
£4,63
£4,63
£10,18
£6,71
£8,74
£8,48
£8,94
£0,52
£0,12
£0,24
£0,52
240,6
£140,35
£24,06
£327,76
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Nose Cone
Nose Cone
1/1
FFS-10
Sheet
Part n°
Bill Of Material
Part No
Op No
10
20
30
40
Description
Rohacell 110 IG (75mm)
Araldite 420
Operation
Cut out 3 blocs of 280x500mm
Glue blocks together with Araldite
420 , put under pressure for better
curing
Draw form from templates on
bonded block and cut out form
Glue block on secondary bulkhead
(FFS-20P), using Araldite 420.
Unit Price
£279/m²
£68,25/kg
Mach/dept
No requ'd
0,5 m²
200g
Tools required
Bandsaw
17
Bandsaw
Printed forms
Araldite 420 A+B, brush, scales
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL nose cone
Comments
Amount of Araldite --> Surface area= 0,38m²*0,6=0,228kg
Op 10:
Curing time for Glue: to check on Araldite spec sheet 'Redux420'
Op 20:
Araldite: 10 parts Araldite 420A over 4 parts Araldite 420B (measured by weight)
Print forms: see nosecone drawings in attachment
op 30:
op 40:
Amount of Araldite --> Surface area= 0,056m²*0,6=0,0336kg
Team Spirit
Date
Time (min)
5
Araldite 420 A+B, brush, scales
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
Signed
Delivery
-
19.3.07
26
8
56
11,2
67,2
Total Cost
£139,50
£13,65
Cost
£2,92
£0,50
£9,92
£1,70
£15,17
£2,60
£4,67
£0,80
-
£153,15
£39,20
£6,72
£199,07
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
1/1
FFS-20
Sheet
Part n°
Bill Of Material
Part No
FFS-21
FFS-22
FFS-231
FFS-232
FFS-24
FFS-25
FFS-26
FFS-27
FFS-28
Description
Frame
Tubes
Internal Reinforcement Triangles
Lateral Reinforcement Triangles
Front Plate
Reinforcement Plates
Brackets
Side Fence
Top Fence
Op No
10
Operation
Mach/dept
weld tubes (FFS-22) to the frame
MIG/TIG
(FFS-21), as shown in Dwg FFS20P
Weld triangles (FFS-231 and FFS232) to Frame (FFS-21) and tubes
MIG/TIG
(FFS-22) as shown in DWg FFS20P
Weld front plate (FFS-24) to frame
MIG/TIG
(FFS-21) as shown in Dwg FFS20P
Weld reinforcement plates (FFSMIG/TIG
25) to the Frame (FFS-21) as
shown in Dwg FFS-20P
Put Frame on primary Bulkhead
and bolt the brackets (FFS-26) to
the Bulkhead.
Weld the brackets (FFS-26) to the
Frame (FFS-21) using bulkhead as MIG/TIG
a Jig
20
30
40
50
60
Unit Price No requ'd
£22,63
1
£2,32
4
£1,16
4
£1,16
4
£10,18
1
£3,36
2
£1,46
6
£1,41
2
£1,49
2
£35/h
£6/h
Tools required
Delivery
intern
intern
intern
intern
intern
intern
intern
intern
intern
Time (min)
9,6
Cost
£5,60
£0,96
23
£13,44
£2,30
2
£1,12
£0,20
6,3
£3,64
£0,63
3
£1,75
£0,30
8,6
£5,04
£0,86
52,5
10,5
63
-
-
-
-
Allen key, spanner
Primary Bulkhead
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
Total £ Labour
Total £ Machine
Subtotal Bulkhead
TOTAL Bulkhead
Total Cost
£22,63
£9,30
£4,63
£4,63
£10,18
£6,71
£8,74
£8,48
£8,94
£36,75
£6,30
£43,05
£104,98
Comments
SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+2,5*2)= 10cm*4 (4 tubes) = 40cm*0,14£/cm=
Op 10:
£5,6 (SAE)
Op 20:
Op 30:
Op 40:
Op 60:
Signed
SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+3,5*2)= 12cm*8 (8 triangels) =
96cm*0,14£/cm= £13,44 (SAE)
SAE estimate welding at 0,14£/cm. Total surface=(8mm/hole)= 0,8cm*10 (10 holes) = 8cm*0,14£/cm=
£1,12 (SAE)
SAE estimate welding at 0,14£/cm. Total surface=(2,5*2+2*4)= 13cm*2 (2 plates) = 26cm*0,14£/cm=
£3,64 (SAE)
SAE estimate welding at 0,14£/cm. Total surface=(3*2)= 6cm*6 (6 plates) = 36cm*0,14£/cm= £5,04
(SAE)
Team Spirit
Date
19.3.07
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Frame
1/1
FFS-21
Sheet
Part n°
Bill Of Material
Part No
Description
Mild steel tube (25x25x2,5)
Op No
10
Operation
Mach/dept
Cut 2 tubes to a length of 280mm,
band saw
with both ends chamfered to 45°
as shown in Dwg FFS-211
Cut 2 tubes to a length of
196,5mm, both ends chamfered to band saw
45°as shown in Dwg FFS-212
weld tubes perpendicular together
MIG/TIG
as shown in Dwg FFS-21
angle
Grind front surface even
grinder
20
30
40
Unit Price
£2,65/m
No requ'd
960mm
Tools required
-
Time (min)
5
5
MIG/TIG welder
11,5
3
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Delivery
-
24,5
4,9
29,4
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
See Dwg FFS-21, FFS-211, FFS-212
Time for cutting tube estimated at 5 min (SAE)
Op 10:
Time for cutting tube estimated at 5 min (SAE)
Op 20:
Time for cutting tube estimated at 5min (SAE)
Op 30:
SAE estimate welding at 0,14£/cm. Total surface=(2,5+2,5+3,5+3,5)= 12cm*4 (4 tubes) =
Op 40:
48cm*0,14£/cm= £6,72 (SAE)
Op 50:
Time for grinding estimated at 3 min (SAE)
Signed
Team Spirit
Date
19.3.07
Total Cost
£2,54
Cost
£2,92
£0,50
£2,92
£0,50
£6,72
£1,15
£1,75
£0,30
-
£2,54
£17,15
£2,94
£22,63
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Tubes
1/1
FFS-22
Sheet
Part n°
Bill Of Material
Part No
Description
Mild steel tube (25x25x2,5)
Op No
10
Operation
Cut 4 tubes to a length of 103mm,
with an angle of 6°as shown in
Dwg FFS-22
de-burr end of tubes using angle
grinder
20
Unit Price (/m) No requ'd
£2,65/m
415mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
See Dwg FFS-22
Time for cutting estimated at 5min (SAE)
Op 20:
Op 30:
Time for de-burring estimated at 3min (SAE)
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
7
3
10
2
12
Total Cost
£1,10
Cost
£4,08
£0,70
£1,75
£0,30
-
£1,10
£7,00
£1,20
£9,30
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
1/1
FFS-231
Sheet
Part n°
Internal R Triangles
Bill Of Material
Part No
Description
Mild steel tube (25x25x3)
Op No
10
Operation
Cut tube to 4 lengths of 48,5mm,
with 48°angles on both ends as
shown in Dwg FFS-231
de-burr tubes all around using
angle grinder
20
Unit Price No requ'd
£2,65/m
200mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding
disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
£35/h
£6/h
Comments
See Dwg FFS-231
Time for cutting estimated at 3min (SAE)
Op 20:
Op 30:
Time for de-burring estimated at 2min (SAE)
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
3
2
5
1
6
Total Cost
£0,53
Cost
£1,75
£0,30
£1,17
£0,20
-
£0,53
£3,50
£0,60
£4,63
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
1/1
FFS-232
Sheet
Part n°
Lateral R Triangles
Bill Of Material
Part No
Description
Mild steel tube (25x25x3)
Op No
10
Operation
Cut tube to 4 lengths of 44mm,
with both 45°angles on both ends
as shown in Dwg FFS-232
de-burr tubes all around using
angle grinder
20
Unit Price No requ'd
£2,65/m
200mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding
disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
See Dwg FFS-232
Time for cutting estimated at 3min (SAE) see Dwg FFS-232
Op 20:
Op 30:
Time for de-burring estimated at 2min (SAE) see Dwg FFS-232
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
3
2
5
1
6
Total Cost
£0,53
Cost
£1,75
£0,30
£1,17
£0,20
-
£0,53
£3,50
£0,60
£4,63
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Front Plate
Sheet
Part n°
1/1
FFS-24
Bill Of Material
Part No
Description
mild steel plate 280mmx200mmx3mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out plate 280x196,5x3mm as
3
Cutting saw
shown on Dwg FFS-24
Drill 10 holes of 8mm dia in plate
5
Pillar drill
Pillar drill, drill 8mm dia
as shown in Dwg
de-burr holes and outline plate
3
Lime / angle grinder: grinding
angle
using angle grinder and de-burring
disc / de-burring tool
grinder
tool
Addition of Time (min)
11
20% set-up allowance (min)
2,2
Total estimated time (min)
13,2
20
30
Unit Price No requ'd
£20,68/m²
0,056m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
£35/h
£6/h
Comments
See Dwg FFS-24
Time for cutting plate estimated at 3min (SAE)
Op 10:
Time for drilling estimated at 5min (SAE)
Op 20:
Op 30:
Time for chamfering estimated at 3min (SAE)
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£1,16
Cost
£1,75
£0,30
£2,92
£0,50
£1,75
£0,30
-
£1,16
£7,70
£1,32
£10,18
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Sheet
Part n°
Reinforcement Plates
1/1
FFS-25
Bill Of Material
Part No
Description
mild steel plate 300mmx25mx3mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out 2 plates 146,5x25x3mm as
5
Cutting saw
shown on Dwg FFS-25
de-burr outline plates using angle
angle
Lime / angle grinder: grinding
3
grinder
grinder
disc
Addition of Time (min)
8
1,6
20% set-up allowance (min)
Total estimated time (min)
9,6
20
Unit Price No requ'd
£20,68/m²
0,0075m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
£35/h
£6/h
Comments
See Dwg FFS-25
Time for cutting plate estimated at 5 min (SAE)
Op 10:
Op 20:
Time for chamfering estimated at 3 min (SAE)
Signed
Group D
Date
19.3.07
Delivery
Total Cost
£0,15
Cost
£2,92
£0,50
£1,75
£0,30
-
£0,15
£5,60
£0,96
£6,71
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Brackets
Sheet
Part n°
1/1
FFS-26
Bill Of Material
Part No
Description
mild steel plate 310mmx20mmx3mm
Op No
20
Operation
Mach/dept
Tools required
Time (min)
Drill 6x7mm holes in the plate as
3
7mm drill
pillar drill
shown on Dwg FFS-26
Chamfer holes on both sides using
2
de-burring tool
pillar drill
de-burring tool
Cut plate to pieces of 60x20x3mm
2,5
circle Saw
(5 cuts)
angle
Lime / angle grinder: grinding
3
Chamfer edges on plates
grinder
disc
Addition of Time (min)
10,5
20% set-up allowance (min)
2,1
Total estimated time (min)
12,6
30
40
50
Unit Price No requ'd
£20,68/m²
0,0062m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
£35/h
£6/h
Comments
See Dwg FFS-26
Time for Pillar drill estimated at 3min (SAE)
Op 20:
Time for chamfering estimated at 2min (SAE)
Op 30:
Time for cutting estimated at 2,5min (SAE)
Op 40:
Op 50:
Time estimated for chamfering at 3min (SAE)
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£0,13
Cost
£1,75
£0,30
£1,17
£0,20
£1,46
£0,25
£1,75
£0,30
-
£0,13
£7,35
£1,26
£8,74
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Side Fence
Sheet
Part n°
1/1
FFS-27
Bill Of Material
Part No
Description
mild steel plate 393mmx135mmx1,5mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out 2 plates of 196,5mm long
3
and 135mm wide as shown in Dwg Cutting saw
FFS-27
Drill 3 holes of 8mm dia in each
4
Pillar drill
Pillar drill, drill 8mm dia
plate as shown in Dwg FFS-27
de-burr holes and outline plate
2
Lime / angle grinder: grinding
angle
using angle grinder and de-burring
disc / de-burring tool
grinder
tool
Addition of Time (min)
9
20% set-up allowance (min)
1,8
Total estimated time (min)
10,8
20
30
Unit Price No requ'd
£20,68/m²
0,053m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
£35/h
£6/h
Comments
See Dwg FFS-27
Time for cutting plate estimated at 3min (SAE)
Op 10:
Time for drilling estimated at 4min (SAE)
Op 20:
Op 30:
Time for chamfering estimated at 2min (SAE)
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£1,10
Cost
£1,75
£0,30
£2,33
£0,40
£1,17
£0,20
-
£1,10
£6,30
£1,08
£8,48
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Top Fence
Sheet
Part n°
1/1
FFS-28
Bill Of Material
Part No
Description
mild steel plate 560mmx135mmx1,5mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out 2 plates of 280mm long
3
and 135mm wide as shown in Dwg Cutting saw
FFS-28
Drill 2 holes of 8mm dia in each
4
Pillar drill
Pillar drill, drill 8mm dia
plate as shown in Dwg FFS-28
de-burr holes and outline plate
2
Lime / angle grinder: grinding
angle
using angle grinder and de-burring
disc / de-burring tool
grinder
tool
Addition of Time (min)
9
20% set-up allowance (min)
1,8
Total estimated time (min)
10,8
20
30
Unit Price No requ'd
£20,68/m²
0,0756m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
£35/h
£6/h
Comments
See Dwg FFS-28
Time for cutting plate estimated at 3min (SAE)
Op 10:
Time for drilling estimated at 5min (SAE)
Op 20:
Op 30:
Time for chamfering estimated at 3min (SAE)
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£1,56
Cost
£1,75
£0,30
£2,33
£0,40
£1,17
£0,20
-
£1,56
£6,30
£1,08
£8,94
1
2
3
5
4
6
7
8
300
A
0
,6
95
FFS-231
°
102,5
102
A
B
3
B
FFS-28
280
C
FFS-22
C
FFS-27
12,65
FFS-25
3
FFS-232
FFS-21
FFS-24
D
196,50
171,50
D
83,50
E
FFS-26
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
TITLE:
2nd Bulkhead Proto
F
MATERIAL:
DWG NO.
A3
FFS-20P
1
2
3
4
WEIGHT:
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
280
2
A
A
FFS-211
FFS-212
FFS-212
196,50
B
45°
FFS-24
B
C
C
FFS-211
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Frame
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
Steel
1
2
WEIGHT:
SCALE:1:5
A4
FFS-21
SHEET 1 OF 1
1
2
3
5
4
6
A
A
B
B
45°
280
C
C
Tube thickness: 2.5mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Frame top tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
25CD4
1
2
WEIGHT:
A4
FFS-211
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
B
B
45°
196,50
C
C
Tube thickness: 2.5mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Frame side tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
25CD4
1
2
WEIGHT:
A4
FFS-212
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
103
B
B
6°
C
C
Tube thickness: 2.5mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Side tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
25CD4
1
2
WEIGHT:
A4
FFS-22
SCALE:2:1
SHEET 1 OF 1
1
2
3
4
25
A
3
B
C
22
,5
48
48°
48°
D
E
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DATE
Spirit Racing Cars
Internal reinforcement
triangles
CHK'D
APPV'D
MFG
Q.A
REVISION
TITLE:
DRAWN
F
DO NOT SCALE DRAWING
MATERIAL:
DWG NO.
WEIGHT:
A4
FFS-231
25CD4
SCALE:1:1
SHEET 1 OF 1
1
2
3
4
25
A
3
B
C
44
22
45°
45°
D
E
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DATE
Spirit Racing Cars
Lateral reinforcement
triangles
CHK'D
APPV'D
MFG
Q.A
REVISION
TITLE:
DRAWN
F
DO NOT SCALE DRAWING
MATERIAL:
DWG NO.
WEIGHT:
A4
FFS-232
25CD4
SCALE:2:1
SHEET 1 OF 1
1
2
3
5
4
6
A
196,50
A
B
B
C
C
280
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Front Plate
CHK'D
D
APPV'D
MFG
Thickness: 3mm
1
2
Q.A
MATERIAL:
DWG NO.
WEIGHT:
A4
FFS-24
mild-steel
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
146,50
B
25
B
C
C
thickness: 3mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Reinforcement plate
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-25
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
20
R10
7
B
B
12,50
3
6°
40
C
C
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Attachment bracket
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-26
SCALE:2:1
SHEET 1 OF 1
1
2
3
5
4
6
A
135
A
B
B
196,50
C
C
thickness: 1.5mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Side fence
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-27
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
280
B
135
B
C
C
Thickness: 1.5mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Top fence
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-28
SCALE:1:5
SHEET 1 OF 1
Bill of Material
Formula Ford Spirit
Part
Sub Assembly
Final Design
Crash Box
Bill Of Material
Part No
FFS-10
FFS-10
FFS-21
FFS-221
FFS-222
FFS-231
FFS-232
FFS-24
FFS-25
FFS-26
FFS-27
FFS-28
FFS-30
FFS-31
FFS-32
FFS-30
Description
Rohacell 110 IG (75mm)
Araldite 420
Mild steel tube (25x25x2)
Mild steel tube (25x25x2)
Mild steel tube (25x25x2)
Mild steel tube (25x25x2)
Mild steel tube (25x25x2)
mild steel plate 280mmx200mmx2mm
mild steel plate 300mmx25mx2mm
mild steel plate 310mmx20mmx3mm
mild steel plate 393mmx30mmx1mm
mild steel plate 560mmx30mmx1mm
Allen Bolt M6x35
Nut M6
Washer M6
Allen Bolt M6x20
Unit Price
£279/m²
£68,25/kg
£2,65/m
£2,65/m
£2,65/m
£2,65/m
£2,65/m
£20,68/m²
£20,68/m²
£20,68/m²
£20,68/m²
£20,68/m²
£0,26
£0,06
£0,06
£0,26
No requ'd
0,5 m²
230g
960mm
210mm
90mm
200mm
200mm
0,056m²
0,0075m²
0,0062m²
0,0118m²
0,017m²
2
2
4
2
TOTAL Bill of materials
Comments
Signed
Team Spirit
Date
19.3.07
Delivery
Total Cost
Degussa
£139,50
Huntsmann
£15,70
£2,54
£0,53
£0,24
£0,53
£0,53
£1,16
£0,15
£0,13
£0,24
£0,35
1 day
£0,52
1 day
£0,12
1 day
£0,24
1 day
£0,52
£163,01
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Final Design
Crash Box
Bill Of Material
Part No
FFS-10
Description
Rohacell Nose Cone
FFS-20
FFS-21
FFS-221
FFS-222
FFS-231
FFS-232
FFS-24
FFS-25
FFS-26
FFS-27
FFS-28
2nd Bulkhead
Frame
Bottom Tubes
Top Tubes
Internal Reinforcement Triangels
Lateral Reinforcement Triangels
Front Plate
Reinforcement Plates
Attachment Brackets
Side Fence
Top Fence
FFS-30
FFS-31
FFS-32
FFS-30
Allen Bolt M6x35
Nut M6
Washer M6
Allen Bolt M6x20
Unit Price
£0,26
£0,06
£0,06
£0,26
No requ'd
1
1
1
2
2
8
8
1
2
6
1
1
internal
internal
internal
internal
internal
internal
internal
internal
internal
internal
internal
2
2
4
2
1 day
1 day
1 day
1 day
Total Labour time (min)
Total £ Labour
Total £ Machine
TOTAL for Proto Crash Box
Comments
Signed
Team Spirit
Date
19.3.07
Delivery
Rohacell
Total Cost
£206,86
£43,05
£22,63
£5,48
£5,16
£4,63
£4,63
£10,18
£6,71
£8,74
£7,62
£7,73
£0,52
£0,12
£0,24
£0,52
251,4
£146,65
£25,14
£334,83
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Nose Cone
Nose Cone
1/1
FFS-10
Sheet
Part n°
Bill Of Material
Part No
Op No
10
20
30
40
Description
Rohacell 110 IG (75mm)
Araldite 420
Unit Price
£279/m²
£68,25/kg
Operation
Mach/dept
Cut out 7 blocs of:
2x(280x200mm); 1x(275x200mm);
1x(250x200mm); 1x(220x200mm);
1x(185x200mm); 1x(150x200mm)
Bandsaw
Glue blocks together with Araldite
420 , put under pressure for better
curing
Draw form from templates on
bonded block and cut out form
No requ'd
0,5 m²
230g
Tools required
Araldite 420 A+B, brush, scales
Printed forms
Bandsaw
Total Cost
£139,50
£15,70
Cost
£7,00
£1,20
£9,92
£1,70
£15,17
£2,60
£4,67
Araldite 420 A+B, brush, scales
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Amount of Araldite --> Surface area= 0,384²*0,6=0,230kg
Op 10:
Curing time for Glue: to check on Araldite spec sheet 'Redux420'
Op 20:
Araldite: 10 parts Araldite 420A over 4 parts Araldite 420B (measured by weight)
Print forms: see nosecone drawings in attachment (FFS-11)
op 30:
op 40:
Amount of Araldite --> Surface area= 0,056m²*0,6=0,0336kg
Date
26
8
Glue block on secondary bulkhead
(FFS-20), using Araldite 420.
Team Spirit
Time (min)
12
17
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
Signed
Delivery
-
19.3.07
63
12,6
75,6
£0,80
-
£155,20
£44,10
£7,56
£206,86
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
1/1
FFS-20
Sheet
Part n°
Bill Of Material
Part No
FFS-21
FFS-221
FFS-222
FFS-231
FFS-232
FFS-24
FFS-25
FFS-26
FFS-27
FFS-28
Description
Frame
Bottom Tubes
Top Tubes
Internal Reinforcement Triangles
Lateral Reinforcement Triangles
Front Plate
Reinforcement Plates
Brackets
Side Fence
Top Fence
Op No
10
Operation
Mach/dept
weld tubes (FFS-221 and FFSMIG/TIG
222) to the frame (FFS-21), as
shown in Dwg FFS-20F
Weld triangles (FFS-231 and FFS232) to Frame (FFS-21) and tubes
MIG/TIG
(FFS-221 and FFS-222) as shown
in Dwg FFS-20F
Weld front plate (FFS-24) to frame
MIG/TIG
(FFS-21) as shown in Dwg FFS20F
Weld reinforcement plates (FFSMIG/TIG
25) to the Frame (FFS-21) as
shown in Dwg FFS-20F
Put Frame on primary Bulkhead
and bolt the brackets (FFS-26) to
the Bulkhead.
Weld the brackets (FFS-26) to the
Frame (FFS-21) using bulkhead as MIG/TIG
a Jig
Weld the fences (FFS-27 and FFS28) to the Frame (FFS-21) using
MIG/TIG
bulkhead as a Jig
20
30
40
50
60
70
Unit Price No requ'd
£22,63
1
£2,74
2
£2,58
2
£1,16
4
£1,16
4
£10,18
1
£3,36
2
£1,46
6
£3,81
2
£3,87
2
£35/h
£6/h
Tools required
Delivery
intern
intern
intern
intern
intern
intern
intern
intern
intern
intern
Time (min)
9,6
Cost
£5,60
£0,96
23
£13,44
£2,30
2
£1,12
£0,20
6,3
£3,64
£0,63
3
£1,75
£0,30
8,6
£5,04
£0,86
4
£5,04
£0,40
-
-
-
Allen key, spanner
Primary Bulkhead
Primary Bulkhead
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
Total £ Labour
Total £ Machine
Subtotal Bulkhead
TOTAL Bulkhead
Total Cost
£22,63
£5,48
£5,16
£4,63
£4,63
£10,18
£6,71
£8,74
£7,62
£7,73
52,5
10,5
63
-
£36,75
£6,30
£43,05
£126,57
Comments
SAE estimate welding at 0,14£/cm.
Op 10:
£5,6 (SAE)
SAE estimate welding at 0,14£/cm.
Op 20:
96cm*0,14£/cm= £13,44 (SAE)
SAE estimate welding at 0,14£/cm.
Op 30:
£1,12 (SAE)
SAE estimate welding at 0,14£/cm.
Op 40:
£3,64 (SAE)
Op 60:
SAE estimate welding at 0,14£/cm.
(SAE)
Signed
Team Spirit
Date
Total surface=(2,5*2+2,5*2)= 10cm*4 (4 tubes) = 40cm*0,14£/cm=
Total surface=(2,5*2+3,5*2)= 12cm*8 (8 triangels) =
Total surface=(8mm/hole)= 0,8cm*10 (10 holes) = 8cm*0,14£/cm=
Total surface=(2,5*2+2*4)= 13cm*2 (2 plates) = 26cm*0,14£/cm=
Total surface=(3*2)= 6cm*6 (6 plates) = 36cm*0,14£/cm= £5,04
19.3.07
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Frame
1/1
FFS-21
Sheet
Part n°
Bill Of Material
Part No
Description
Mild steel tube (25x25x2)
Op No
10
Operation
Mach/dept
Cut 2 tubes to a length of 280mm,
band saw
with both ends chamfered to 45°
Cut 2 tubes to a length of
196,5mm, both ends chamfered to band saw
45°as in Dwg FFS-21
weld tubes perpendicular together
MIG/TIG
as shown in Dwg FFS-21
angle
Grind front surface even
grinder
20
30
40
Unit Price
£2,65/m
No requ'd
960mm
Tools required
-
Time (min)
5
5
MIG/TIG welder
11,5
3
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Delivery
-
24,5
4,9
29,4
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting tube estimated at 5 min (SAE) see Dwg FFS-211
Op 10:
Time for cutting tube estimated at 5 min (SAE) see Dwg FFS-212
Op 20:
Time for cutting tube estimated at 5min (SAE)
Op 30:
SAE estimate welding at 0,14£/cm. Total surface=(2,5+2,5+3,5+3,5)= 12cm*4 (4 tubes) =
Op 40:
48cm*0,14£/cm= £6,72 (SAE)
Op 50:
Time for grinding estimated at 3 min (SAE)
Signed
Team Spirit
Date
19.3.07
Total Cost
£2,54
Cost
£2,92
£0,50
£2,92
£0,50
£6,72
£1,15
£1,75
£0,30
-
£2,54
£17,15
£2,94
£22,63
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Bottom Tubes
1/1
FFS-221
Sheet
Part n°
Bill Of Material
Part No
Description
Mild steel tube (25x25x2)
Op No
10
Operation
Cut 2 tubes to a length of 103mm,
with an angle of 6°as shown in
Dwg FFS-221
de-burr end of tubes using angle
grinder
20
Unit Price (/m) No requ'd
£2,65/m
210mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting estimated at 3min (SAE) see Dwg FFS-221
Op 10:
Op 20:
Time for de-burring estimated at 3min (SAE)
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
3
3
6
1,2
7,2
Total Cost
£0,56
Cost
£1,75
£0,30
£1,75
£0,30
-
£0,56
£4,20
£0,72
£5,48
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Top Tubes
1/1
FFS-222
Sheet
Part n°
Bill Of Material
Part No
Description
Mild steel tube (25x25x2)
Op No
10
Operation
Cut 2 tubes to a length of 43mm,
with an angle of 6°as shown in
Dwg FFS-222
de-burr end of tubes using angle
grinder
20
Unit Price (/m) No requ'd
£2,65/m
90mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting estimated at 3min (SAE) see Dwg FFS-222
Op 10:
Op 20:
Time for de-burring estimated at 3min (SAE)
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
3
3
6
1,2
7,2
Total Cost
£0,24
Cost
£1,75
£0,30
£1,75
£0,30
-
£0,24
£4,20
£0,72
£5,16
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
1/1
FFS-231
Sheet
Part n°
Internal R Triangles
Bill Of Material
Part No
Description
Mild steel tube (25x25x2)
Op No
10
Operation
Cut tube to 4 lengths of 48,5mm,
with 48°angles on both ends as
shown in Dwg FFS-231
de-burr tubes all around using
angle grinder
20
Unit Price No requ'd
£2,65/m
200mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding
disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting estimated at 3min (SAE) see Dwg FFS-231
Op 20:
Op 30:
Time for de-burring estimated at 2min (SAE)
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
3
2
5
1
6
Total Cost
£0,53
Cost
£1,75
£0,30
£1,17
£0,20
-
£0,53
£3,50
£0,60
£4,63
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
1/1
FFS-232
Sheet
Part n°
Lateral R Triangles
Bill Of Material
Part No
Description
Mild steel tube (25x25x2)
Op No
10
Operation
Cut tube to 4 lengths of 44mm,
with both 45°angles on both ends
as shown in Dwg FFS-232
de-burr tubes all around using
angle grinder
20
Unit Price No requ'd
£2,65/m
200mm
Mach/dept
Tools required
Band Saw
-
angle
grinder
Lime / angle grinder: grinding
disc
Addition of Time (min)
20% set-up allowance (min)
Total estimated time (min)
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting estimated at 3min (SAE) see Dwg FFS-232
Op 20:
Op 30:
Time for de-burring estimated at 2min (SAE) see Dwg FFS-232
Signed
Team Spirit
Date
19.3.07
Delivery
Time (min)
3
2
5
1
6
Total Cost
£0,53
Cost
£1,75
£0,30
£1,17
£0,20
-
£0,53
£3,50
£0,60
£4,63
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Front Plate
Sheet
Part n°
1/1
FFS-24
Bill Of Material
Part No
Description
mild steel plate 280mmx200mmx2mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out plate 280x196,5x3mm as
3
Cutting saw
shown on Dwg FFS-24
Drill 10 holes of 8mm dia in plate
5
Pillar drill
Pillar drill, drill 8mm dia
as shown in Dwg
de-burr holes and outline plate
3
Lime / angle grinder: grinding
angle
using angle grinder and de-burring
disc / de-burring tool
grinder
tool
Addition of Time (min)
11
20% set-up allowance (min)
2,2
Total estimated time (min)
13,2
20
30
£35/h
£6/h
Unit Price No requ'd
£20,68/m²
0,056m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting plate estimated at 3min (SAE) see Dwg FFS-24
Op 10:
Time for drilling estimated at 5min (SAE) see Dwg FFS-24
Op 20:
Op 30:
Time for chamfering estimated at 3min (SAE)
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£1,16
Cost
£1,75
£0,30
£2,92
£0,50
£1,75
£0,30
-
£1,16
£7,70
£1,32
£10,18
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Sheet
Part n°
Reinforcement Plates
1/1
FFS-25
Bill Of Material
Part No
Description
mild steel plate 300mmx25mx2mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out 2 plates 146,5x25x3mm as
5
Cutting saw
shown on Dwg FFS-25
de-burr outline plates using angle
angle
Lime / angle grinder: grinding
3
grinder
grinder
disc
Addition of Time (min)
8
1,6
20% set-up allowance (min)
Total estimated time (min)
9,6
20
Unit Price No requ'd
£20,68/m²
0,0075m²
£35/h
£6/h
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting plate estimated at 5 min (SAE) see Dwg FFS-25
Op 10:
Op 20:
Time for chamfering estimated at 3 min (SAE) see Dwg FFS-25
Signed
Group D
Date
19.3.07
Delivery
Total Cost
£0,15
Cost
£2,92
£0,50
£1,75
£0,30
-
£0,15
£5,60
£0,96
£6,71
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Brackets
Sheet
Part n°
1/1
FFS-26
Bill Of Material
Part No
Description
mild steel plate 310mmx20mmx3mm
Op No
20
Operation
Mach/dept
Tools required
Time (min)
Drill 6x7mm holes in the plate as
3
7mm drill
pillar drill
shown on Dwg FFS-26
Chamfer holes on both sides using
2
de-burring tool
pillar drill
de-burring tool
Cut plate to pieces of 60x20x3mm
2,5
circle Saw
(5 cuts)
angle
Lime / angle grinder: grinding
3
Chamfer edges on plates
grinder
disc
Addition of Time (min)
10,5
20% set-up allowance (min)
2,1
Total estimated time (min)
12,6
30
40
50
£35/h
£6/h
Unit Price No requ'd
£20,68/m²
0,0062m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for Pillar drill estimated at 3min (SAE) see Dwg FFS-26
Op 20:
Time for chamfering estimated at 2min (SAE) see Dwg FFS-26
Op 30:
Time for cutting estimated at 2,5min (SAE) see Dwg FFS-26
Op 40:
Op 50:
Time estimated for chamfering at 3min (SAE) see Dwg FFS-26
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£0,13
Cost
£1,75
£0,30
£1,17
£0,20
£1,46
£0,25
£1,75
£0,30
-
£0,13
£7,35
£1,26
£8,74
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Side Fence
Sheet
Part n°
1/1
FFS-27
Bill Of Material
Part No
Description
mild steel plate 393mmx30mmx1mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out 2 plates of 196,5mm long
3
and 30mm wide as shown in Dwg Cutting saw
FFS-27
Drill 3 holes of 8mm dia in each
4
Pillar drill
Pillar drill, drill 8mm dia
plate as shown in Dwg FFS-27
de-burr holes and outline plate
2
Lime / angle grinder: grinding
angle
using angle grinder and de-burring
disc / de-burring tool
grinder
tool
Addition of Time (min)
9
20% set-up allowance (min)
1,8
Total estimated time (min)
10,8
20
30
£35/h
£6/h
Unit Price No requ'd
£20,68/m²
0,0118m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting plate estimated at 3min (SAE) see Dwg FFS-27
Op 10:
Time for drilling estimated at 4min (SAE) see Dwg FFS-27
Op 20:
Op 30:
Time for chamfering estimated at 2min (SAE) see Dwg FFS-27
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£0,24
Cost
£1,75
£0,30
£2,33
£0,40
£1,17
£0,20
-
£0,24
£6,30
£1,08
£7,62
Costing Tender
Formula Ford Spirit
Part
Sub Assembly
Bulkhead
Top Fence
Sheet
Part n°
1/1
FFS-28
Bill Of Material
Part No
Description
mild steel plate 560mmx30mmx1mm
Op No
10
Operation
Mach/dept
Tools required
Time (min)
Cut out 2 plates of 280mm long
3
and 30mm wide as shown in Dwg Cutting saw
FFS-28
Drill 2 holes of 8mm dia in each
4
Pillar drill
Pillar drill, drill 8mm dia
plate as shown in Dwg FFS-28
de-burr holes and outline plate
2
Lime / angle grinder: grinding
angle
using angle grinder and de-burring
disc / de-burring tool
grinder
tool
Addition of Time (min)
9
20% set-up allowance (min)
1,8
Total estimated time (min)
10,8
20
30
£35/h
£6/h
Unit Price No requ'd
£20,68/m²
0,017m²
Total Raw Materials
Total £ Labour
Total £ Machine
TOTAL
Comments
Time for cutting plate estimated at 3min (SAE) see Dwg FFS-28
Op 10:
Time for drilling estimated at 5min (SAE) see Dwg FFS-28
Op 20:
Op 30:
Time for chamfering estimated at 3min (SAE) see Dwg FFS-28
Signed
Group D
Date
19.3.07
Delivery
-
Total Cost
£0,35
Cost
£1,75
£0,30
£2,33
£0,40
£1,17
£0,20
-
£0,35
£6,30
£1,08
£7,73
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1
2
3
5
4
6
7
8
300
A
A
95
,5
5°
103
288
43
FFS-231
B
2
30
17
B
FFS-27
280
C
FFS-28
C
FFS-222
FFS-24
2
FFS-25
FFS-232
196,50
D
171,50
D
FFS-21
FFS-26
84
E
FFS-221
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
2nd Bulkhead
CHK'D
APPV'D
MFG
F
Q.A
1
2
3
4
MATERIAL:
WEIGHT:
DWG NO.
SCALE:1:3
A3
FFS-20
SHEET 1 OF 1
1
2
3
5
4
6
280
2
A
A
FFS-211
FFS-212
FFS-212
196,50
B
45°
FFS-24
B
C
C
FFS-211
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Frame
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
Steel
1
2
WEIGHT:
SCALE:1:5
A4
FFS-21
SHEET 1 OF 1
1
2
3
5
4
6
A
A
B
B
45°
280
C
C
Tube thickness: 2mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Frame top tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
25CD4
1
2
WEIGHT:
DWG NO.
A4
FFS-211
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
B
B
45°
196,50
C
C
Tube thickness: 2mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Frame side tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
25CD4
1
2
WEIGHT:
DWG NO.
A4
FFS-212
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
103
B
B
6°
C
C
Tube thickness: 2mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Bottom side tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
25CD4
1
2
WEIGHT:
DWG NO.
A4
FFS-221
SCALE:2:1
SHEET 1 OF 1
1
2
3
5
4
A
6
A
43
B
B
6°
C
C
Tube thickness: 2mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Top side tube
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
25CD4
1
2
WEIGHT:
DWG NO.
A4
FFS-222
SCALE:2:1
SHEET 1 OF 1
1
2
3
4
25
A
2
B
C
22
,5
48
48°
48°
D
E
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DATE
Spirit Racing Cars
Internal reinforcement
triangles
CHK'D
APPV'D
MFG
Q.A
REVISION
TITLE:
DRAWN
F
DO NOT SCALE DRAWING
MATERIAL:
DWG NO.
WEIGHT:
A4
FFS-231
25CD4
SCALE:1:1
SHEET 1 OF 1
1
2
3
4
25
A
2
B
C
44
22
45°
45°
D
E
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DATE
Spirit Racing Cars
Lateral reinforcement
triangles
CHK'D
APPV'D
MFG
Q.A
REVISION
TITLE:
DRAWN
F
DO NOT SCALE DRAWING
MATERIAL:
DWG NO.
WEIGHT:
A4
FFS-232
25CD4
SCALE:2:1
SHEET 1 OF 1
1
2
3
5
4
6
A
196,50
A
B
B
C
C
280
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Front Plate
CHK'D
D
APPV'D
MFG
Thickness: 2mm
1
2
Q.A
MATERIAL:
DWG NO.
WEIGHT:
A4
FFS-24
mild-steel
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
146,50
B
25
B
C
C
thickness: 2mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Reinforcement plate
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-25
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
20
R10
7
B
B
12,50
3
6°
40
C
C
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Attachment bracket
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-26
SCALE:2:1
SHEET 1 OF 1
1
2
3
5
4
6
A
A
196,50
B
30
B
C
C
thickness: 1mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Side fence
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-27
SCALE:1:5
SHEET 1 OF 1
1
2
3
5
4
6
A
A
280
B
30
B
C
C
thickness: 1mm
UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE IN MILLIMETERS
SURFACE FINISH:
TOLERANCES:
LINEAR:
ANGULAR:
NAME
DEBUR AND
BREAK SHARP
EDGES
FINISH:
SIGNATURE
DO NOT SCALE DRAWING
REVISION
Spirit Racing Cars
DATE
TITLE:
DRAWN
Top fence
CHK'D
D
APPV'D
MFG
Q.A
MATERIAL:
DWG NO.
mild steel
1
2
WEIGHT:
A4
FFS-28
SCALE:1:5
SHEET 1 OF 1
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