Design and FEA of a Recumbent Trike

International Journal of Applied Engineering Research, ISSN 0973-4562 Vol.7 No.11 (2012)
© Research India Publications;
http://www.ripublication.com/ijaer.htm
Design and FEA of a Recumbent Trike
*Er. Vikas Gulati, **Er. Sameer Mehta, *** Ankur Kashyap,*** Kartik Pawar
* Department of Mechanical Engineering, Geeta Institute of Management & Technolgy,
Kuruskshetra. [email protected], +91-98967-38032
** Department of Mechanical Engineering, Geeta Institute of Management & Technolgy,
Kuruskshetra. [email protected], +91-99911-14003
*** Department of Mechanical Engineering, Geeta Institute of Management & Technolgy, Kuruskshetra.
[email protected], +91-97298-90050
**** Department of Mechanical Engineering, Geeta Institute of Management & Technolgy, Kuruskshetra.
[email protected], +91-99969-12300
Abstract
This paper presents the design of an eco-friendly human
powered vehicle with a compounded electric drive system.
The focus has been laid on the simplicity in design, high
performance, easy maintenance and safety at very reasonable
prices. Most of the components have been chosen keeping in
mind the easy availability and reliability. This paper provides
the details of components used, and performance parameters
taken into consideration while designing the vehicle. This
hybrid human powered trike is very efficient, ergonomically
designed and can be proved as a better replacement of fueled
vehicle contributing towards the environment sustainability.
1. INTRODUCTION
Transportation plays a key role in overall development of the
society both economically and socially. Nevertheless it has
many spillover effects such as traffic congestion, safety,
global warming and depletion of non-renewable sources of
energy. Transportation assists in economic growth by making
accessibility to resources and markets. In India there are
presently close to 18 million petrol-powered two wheelers and
about 1.5 million petrol and diesel powered three wheelers and
there population is growing at a rate of about 15% per annum
[1]. It is a common sight in India and in other developing
countries that during traffic jams in congested areas of cities
these vehicles produces tremendous air pollution. Therefore,
the aim was to design a three wheeled human powered
electrically assisted vehicle having simple, high performance,
easy maintenance and safety at a very reasonable price, hence
capable of replacing fueled vehicles contributing towards
environmental sustainability.
2. DESIGN CONSIDERATIONS
Human powered hybrid vehicles present the new milestone in
the realm of "Green Technology". The vehicle that is cheap to
buy, cheap to run and can be used from a track racer to a
grocery seller everybody contributing towards a green
environment. In literature, there are two available designs of
vehicle:
2.1 Delta: The delta type of trike has one wheel in the front
and two wheels in the rear. These types of trike can give its
best in steering as it can have a zero turning radius. The power
to the rear wheels of the delta trike ensures no slipping during
cornering.
2.2 Tadpole: The tadpole type of trike has two wheels in the
front and one wheel in the rear.
Both the trikes have their pros and cons. But tadpole
configuration always has certain advantages over the delta
configuration in almost every field. Being a rear wheel driven
configuration, the tadpole configuration will have all the
tractive effort available from its share of the weight. Also
because of the major weight on the front side of the vehicle
there is much grip available for both steering and braking.
Electrically assisted tadpole trikes are much more stable when
compared during cornering. Delta trikes on the other hand has
less front weightage due to which it can’t give its best in both
braking and steering. Electrically assisted delta trikes are more
unstable. After analyzing both the designs it is preferred to
choose tadpole over the delta.
3. DESIGN METHODOLOGY
The design methodology involved in the development of the
trike design consists of mainly two steps which ultimately led
to a design which is ergonomic, aerodynamic, highly
engineered and easy to manufacture. The design methodology
has the following two processes:
3.1 Recognition of customer’s need: Designing is indeed a
research topic and needs high level of research and analysis of
the current situation. It actually involves the recognition of
customer’s need. This process includes various steps which
are depicted below:
 Market research identifies customers and needs
 R&D creates ideas that are relevant to an organization's
capabilities
 Needs arise from dissatisfaction
 Technology push
3.2 Definition of a problem task: After the successful
completion of the recognition of the customer’s need, the
definition of a problem task comes which includes the
following steps:
 Design Specification
 Selecting product ideas
 Compiling & apply technical knowledge
 Identify resources
International Journal of Applied Engineering Research, ISSN 0973-4562 Vol.7 No.11 (2012)
© Research India Publications;
http://www.ripublication.com/ijaer.htm

Prioritize design goals & continue to refine
4. DESIGN OVERVIEW
The vehicle has an innovative tadpole recumbent design which
is aerodynamic, ergonomically designed so that it can be used
for travelling far areas. The recumbent design of the trike
enables the drivers to have a very comfortable ride at all times.
The trike can also have an option of adjustable seats in order
to cope with the different heights. The trike roll cage has been
designed in order to enhance the overall safety of the vehicle
in case of a front or roll over impact. The ergonomically
designed side impact member prevents the drivers from any
kind of side impact. The side impact can also be hydraulically
opened to allow easy entry and egress of the driver. The trike
is also equipped with both front and rear suspension system
which provides a comfortable and smoother ride to the drivers.
The braking system has been designed in order to have better
stability of the vehicle during braking. The innovative
transmission system gives a nice tractive effort by reducing
any slip. Fig shows a detailed view of the concept trike.
Fig. 2 Chassis 3D Views
5.2 Wheel Base and Track Width
The wheel base and track width of the trike decides the
steering geometry which is one of the most important factor
that is to be considered while designing. The longer the wheel
base the higher the high speed stability. But a much longer
wheel base reduces the maneuverability. Therefore an
optimum wheel base of 51.7 inches was chosen with an
overall length of 88.3 inches. The wider the track width, lesser
is the susceptibility of vehicle to capsize during cornering.
However, if too wide, the vehicle becomes impracticable on
most track lanes. Therefore, an optimum track width of 42.8
inches has been chosen.
5.3 Weight Distribution
The trike has a 60/40 weight distribution i.e. 60% weight on
the front and rest on the rear end. The weight distribution of a
trike dictates how well it handles the applied load. More is the
weight on the front wheel better is the cornering. However,
too much weight on the front wheel causes the rear wheel to
wear out during hard cornering. Therefore a trike with 60/40
weight distribution is optimum. The total weight of this
electric trike is 65 Kg.
Fig. 1 Trike 3D Model
5. TRIKE SPECIFICATIONS
The recumbent trike has many innovative features which gives
it an appealing look. It has an innovative USS Steering System
(Under Seat Steering). The trike can be simultaneously driven
by both human and electric power. The trike can
accommodate two drivers ergonomically and safely.
5.1 Trike Frame
The trike frame has been designed keeping in view the overall
safety of the drivers. It was also kept in mind the various
systems that have to be incorporated in the vehicle like
suspension system, braking system, transmission system, etc.
The frame of the trike resembles with the head of an alien. The
trike has an innovative USS Steering system which allows
both the drivers to steer the vehicle. This steering system has
been used in order to give the drivers a freedom to ride the
vehicle from either left side or right side.
The chassis 3D views are shown below in the fig. 2.
5.4 Tyres and Rims
Tires are the most important part in any vehicle design as they
are the part which provides contact between the road and the
vehicle. Road shocks are first absorbed by tires and then
transmitted to suspension [4].The tyres are chosen in such a
way that it must provide traction in all kind if surfaces without
slipping. The trike has a tadpole configuration i.e. two wheels
at the front and one wheel at the rear. The tyres at the front
and the rear are tabulated below:
Table 1: Tyre Size
Position
Front
Rear
Size
16 Inches
20 Inches
The front part has 16 inches wheels which is responsible
for the steering responsiveness and effortless steering. The
rear wheel has been chosen precisely so that the targeted top
speed can be achieved without any compromise in the COG of
the trike. Therefore it has been chosen as 20 inches.
International Journal of Applied Engineering Research, ISSN 0973-4562 Vol.7 No.11 (2012)
© Research India Publications;
http://www.ripublication.com/ijaer.htm
5.5 Braking System
The electric trike used mechanical disc brakes on all wheels
which can be locked simultaneously as desired. The front two
disc rotors are controlled by a double barrel lever which can
lock both the front discs simultaneously to prevent any
skidding or slip. This also prevents the toppling of the trike.
The expected braking distance is 2 meters. The overall braking
system is shown in the fig below.
Fig. 5 Rear Dual Shocker Swing Arm Suspension
5.7 Steering System
The trike uses an innovative Under Seat Steering System
having a true Ackermann steering geometry. In this the inner
wheel can have a maximum angle of 40 degrees so that outer
wheel angle is 24.84 degrees. The steering system uses a 180
degrees bell crank in order to actuate the turning of the wheels
through tie rods. The trike has an effective turning radius of
3.25 meters.
Fig. 3 Braking System of the Trike
5.6 Suspension System
A double wishbone or double A arm suspension has been used
in the trike in front part of the vehicle in order to have a
smoother and comfort drive. The trike also has a dual shocker
swing arm suspension at the rear end. The combination of both
the suspension system makes it a vehicle with proper handling
and braking. The double wishbone suspension has a maximum
deflection of 4 inches.
Fig. 6 Steering Ackermann Geometry
The steering geometry calculations are tabulated below
as:
Table 2: Turning Radius
Turning Radius ( R )
Inner front wheel
Outer front wheel
Fig. 4 Front Double Wishbones Suspension
The rear suspension has a maximum deflection of 4
inches which keeps the motor mounted in the rear part of the
trike shock free and intact.
Formula
b/sin A * ((a-c)/2)
b/sin B + ((a-c)/2)
where wheel base,
pivot center,
track,
inner wheel angle,
outer wheel angle,
Value
0.101 m
3.250 m
b = 1.11m
c = 1.098m
a = 1.202m
A = 40 degrees
B = 24.84 degrees
5.8 Transmission System
The trike can be driven by both the drivers. The trike is
powered by both human and electric power. The drivers can
power the vehicle using the two crank wheels in the front
portion of the chassis. These two crank wheels deliver the
power to the idler axle mounted in the rear part which
ultimately drives the rear wheel through freewheels. The
overall manual transmission has a 21 Speed Gear assembly.
International Journal of Applied Engineering Research, ISSN 0973-4562 Vol.7 No.11 (2012)
© Research India Publications;
http://www.ripublication.com/ijaer.htm
cage has been tested for stress induced and deformation during
front impact and roll over. These tests gave very important
results which helped to estimate the factor of safety of the
electric trike. Fig. shows the roll cage which was analyzed in
ANSYS 13.0.
Fig. 7 Overall Transmission System
The electrical transmission of the trike consists of a PMDC
motor and a flywheel. The PMDC motor is powered by a
battery which is mounted in the front part of the chassis in an
insulated compartment. The PMDC motor and flywheel belt
drive also includes an alternator to recharge the battery. The
PMDC motor and battery specifications are tabulated below:
Table 3: Motor and Battery Specification
S.No.
PMDC Motor
1.
2.
3.
4.
5.
6.
Battery
7.
8.
9.
10.
11.
ITEM
SPECIFICATION
Power
Voltage
RPM
Max. Torque
Max. Current
Weight
0.5 HP (373Watts)
12 Volts
1500
24N-m
20 A-Hr
11 Kg
Type
Make
Output Voltage
Peak Current
Weight
SMF Battery
Exide
12 Volts
26 A-Hr
10 Kg
6. FINITE ELEMENT ANALYSIS
The finite element method (FEM) is a numerical technique for
finding approximate solutions to partial differential
equations (PDE) and their systems, as well as (less
often) integral equations. In simple terms, FEM is a method
for dividing up a very complicated problem into small
elements that can be solved in relation to each other. FEM is a
special case of the more general Galerkin method with
polynomial approximation functions. The solution approach is
based on eliminating the spatial derivatives from the PDE
[6]. Although Finite Element techniques are used to model
many different phenomenon, at Dynamic Analysis we
specialize in modeling the response of systems to stress,
vibration and thermal loads. The roll cage of the trike has been
completely analyzed using the FEM analysis software
(ANSYS 13.0) which ensures the overall safety of the drivers.
Extraordinary measures were taken to make driving as safe as
possible. Experience and responsible engineering have yielded
nearly perfect safety record and driver confidence. The roll
Fig. 8 Isometric View of the Chassis
6.1 FEATURE BASED MODELLING
Solid modeling is a consistent set of principles for
mathematical and computer modeling of three-dimensional
solids. Solid modeling is distinguished from related areas
of geometric modeling and computer graphics by its emphasis
on physical fidelity. Together, the principles of geometric and
solid modeling form the foundation of computer-aided
design and in general support the creation, exchange,
visualization, animation, interrogation, and annotation of
digital models of physical objects. A solid model of chassis
frame was prepared using weldments to convert 2-D sketch to
pipe structure.
Fig. 9 Geometry Used in FEA
6.2 MATERIAL SELECTION
The FEM analysis of the complete chassis was carried out
with help of analysis software (ANSYS 13.0). Figure 8 shows
the geometry which was used for the analysis purpose.
Material selection is a step in the process of designing any
physical object. In the context of product design, the main
goal of material selection is to minimize cost while meeting
product performance goals. Systematic selection of the best
material for a given application begins with properties and
costs of candidate materials. For building the trike, the
materials have been narrowed down to three metals; carbon
steel, CroMo and aluminium [2]. The material selection
criteria are tabulated below:
International Journal of Applied Engineering Research, ISSN 0973-4562 Vol.7 No.11 (2012)
© Research India Publications;
http://www.ripublication.com/ijaer.htm
Table 4: Material Selection
Materi
al
O.D
.
(mm
)
Thickne
ss
(mm)
E
(Gpa
)
Sy
(Mp
a)
Weigh
t (Kg)
per m
1018
25.4
3.05
205
365
1.68
1021
25.4
3.05
205
405
1.68
1021
28.5
7
1.65
205
405
1.09
1021
31.7
5
1.65
205
405
1.22
Best
1021
38.1
2.1082
205
405
1.86
Used for
Main
Member
1021
31.7
5
2.1082
205
405
1.53
OK
Result
Referen
ce
Used for
Side
Member
Stiffnes
s
too
low
6.3 MESH GENERATION
Mesh
generation is
the
practice
of
generating
a polygonal or polyhedral mesh that approximates a geometric
domain. The term "grid generation" is often used
interchangeably. Typical uses are for rendering to a computer
screen or for physical simulation such as finite element
analysis or computational fluid dynamics. Three-dimensional
meshes created for finite element analysis need to consist
of tetrahedral, pyramids, prisms or hexahedra [7]. Those used
for
the finite
volume
method can
consist
of
arbitrary polyhedral. Those used for finite difference
methods usually need to consist of piecewise structured arrays
of hexahedra known as multi-block structured meshes. The
elements were given a tetrahedral connectivity. The details are
tabulated below:
7. ANALYSIS
Finite Element Analysis is a mathematical modeling technique
used to determine the response of real structures to external
(and sometimes internal) loads. Although Finite Element
techniques are used to model many different phenomenon, at
Dynamic Analysis we specialize in modeling the response of
systems to stress, vibration and thermal loads. During the
analysis the working stress units for stress are N/mm2 [3].
7.1 FRONT IMPACT ANALYSIS (DYNAMIC AT 1G)
The analysis of the chassis when it is subjected to an impact
load from the front is called as front impact test. Front Impact
test can be used to calculate both Displacement and Stress.
Figure 11 and 12 show the results of the front impact analysis
of the chassis. Figure 11 shows the stress induced whereas the
figure 12 shows the deformation during the side impact test.
From these analysis results, the maximum stress was found
out to be 344.7 M Pa with a factor of safety of 1.37.
Fig. 11 Stress Induced during Front Impact at 1G
Moreover, the analysis shows that the maximum
deflection was 0.0004mm during the front impact at 1G which
yields a factor of safety of 1.37.
Table 5: Analysis Statistics
Connectivity
TE4 (Tetrahedral)
Entity
Nodes
Elements
Statistics
76570 ( 100.00% )
Size
397615
76570
Fig. 12 Displacement during Front Impact at 1G
Fig. 10 Mesh Generated Using ANSYS 13.0
7.2 ROLL OVER ANALYSIS (DYNAMIC AT 10G)
To approximate the worst case scenario that the vehicle will
see, research into the forces the human body can endure was
completed. The research found that the human body will pass
out at loads much higher than 9 times the force of gravity or 9
G’s [5]. A value of 10 G’s was set as the goal point for an
extreme worst case collision. Figure 13 shows the results of
the roll over analysis for stress at 10G. During the analysis
International Journal of Applied Engineering Research, ISSN 0973-4562 Vol.7 No.11 (2012)
© Research India Publications;
http://www.ripublication.com/ijaer.htm
point masses were defined at various loading conditions. The
maximum stress induced was calculated to be 289.3 M Pa with
a factor of safety of 1.16.
[4]
[5]
[6]
[7]
Fig.13 Stress Induced during Roll Over Impact at 10G
Moreover, the analysis shows that the maximum
deflection was 0.007mm during the roll over impact at 10G.
Fig. 14 Deformation during Roll Over Impact at 10G
8. CONCLUSIONS
Complete design of an electric trike has been reported in this
paper. The use of solid modeling helped to perform high
quality design. Finally the chassis of trike was analyzed to
evaluate its capability and endurance, and the results were
monitored for further improvement. Extraordinary measures
were taken to make the driving of electric trike as safe as
possible. Experience and responsible engineering have yielded
a near perfect safety record and driver confidence. This design
of electric trike can be considered by the industries for mass
production in order to replace the fueled vehicles contributing
towards environment sustainability.
REFERENCES
[1] Anil K Rajvanshi, Electric and improved cycle
rickshaw as a sustainable transport system for India,
Current Science, Vol. 83, No. 6, September 2002.
[2] Manpreet Singh Bhatia, Human Powered Trike, First
National Conference on Advances in Mechanical
Engineering (NCAME -2011), 20th -21st May 2011.
[3] Manpreet Singh Bhatia and Amit Chauhan,
Recumbent Human Powered Trike with Compounded
Electric Drive System, International Journal of
Applied Engineering Reasearch, Vol. 6 No. 18 (2011)
,pp. 3126-3120
Complete Design and Finite Element Analysis of an
all Terrain Vehicle, International Journal of
Mechanical and Industrial Engineering (IJMIE), ISSN
No. 2231 –6477, Volume-1, Issue-3, 2012.
Elert, Glenn. “Acceleration That Would Kill a
Human,”http://hypertextbook.com/facts/2004/YuriyRa
failov.shtml.
http://en.wikipedia.org/wiki/Finite_element_method
http://en.wikipedia.org/wiki/Mesh_generation