PROJECT REPORT ON
IMPLEMENTATION OF COMPOSITE MATERIALS ON A
FORMULA STYLED RACE CAR
SUBMITTED IN PARTIAL FULFILMENT OF THE
REQUIREMENTS FOR THE DEGREE OF
BACHELOR OF ENGINEERING
BY
Sagar Doshi (Roll No 0915091)
Kunal Parikh (Roll No 0915055)
UNDER THE GUIDANCE OF
PROF. Ajay K. Gangrade
DEPARTMENT OF MECHANICAL ENGINEERING
K. J. SOMAIYA COLLEGE OF ENGINEERING, MUMBAI
UNIVERSITY OF MUMBAI
2012-2013
PROJECT REPORT ON
IMPLEMENTATION OF COMPOSITE MATERIALS ON A
FORMULA STYLED RACE CAR
Submitted in partial fulfillment of the requirements
for the degree of
Bachelor of Engineering
By
Sagar Doshi
Kunal Parikh
Under the guidance of
Prof. Ajay K. Gangrade
Department of Mechanical Engineering
K. J. Somaiya College of Engineering, Mumbai
University of Mumbai
2012-2013
CERTIFICATE
This is to certify that the project entitled
IMPLEMENTATION OF COMPOSITE MATERIALS ON A FORMULA
STYLED RACE CAR
Submitted by
Sagar Doshi (0915091)
Kunal Parikh (0915055)
in partial fulfillment of the requirements for the degree of Bachelor of
Engineering in Mechanical Engineering is approved
Project Guide
Internal Examiner_________
Prof. __________
External Examiner ________
Head of Department __________
Principal __________
Department of Mechanical Engineering
K. J. Somaiya College of Engineering, Mumbai
University of Mumbai
2012-2013
ACKNOWLEDGMENT
We would like to express our heartfelt gratitude to all the people who saw us through
the project; to all those who provided support, talked things over, read, wrote, offered
comments, guided us in the right direction and assisted in the design as well as
fabrication of parts.
We would like to thank Prof. Ajay K. Gangrade, our guide, for enabling us to work on
this interesting but rarely treaded world of composites.
We would like to thank Dow Chemical India and specially Mr. Nilesh Tawde for his
immense patience and support in terms of knowledge as well as various kinds of
experiments on a variety of composite materials. We also thank Optima Technology,
where we did all our CNC routing of our MDF moulds, Evoniks, for sponsoring us with
Rohacell foam, ARAI(Automotive Research Association of India), for carrying out our
crash test on impact structures, Muktagiri Industries, who provided us with carbon fiber
and finally, Mr. Paresh Kacheria for sponsoring us with glass fiber.
We also acknowledge the constant and unerring support of our parents and friends.
CONTENTS
Sr. No. Page Title
Page
No
1
1.
List of Tables & Figures
2.
Introduction
3
2.1. Aim
3
2.2. Composite Materials – A brief overview
3
Literature Review
5
3.1. History
5
3.2. Constituents
5
3.3. Fabrication Methods
.7
3.4. Finishing Methods
10
3.5. Tooling
10
3.6. Physical Properties
10
3.7. Failure
11
3.8. Testing
12
Impact Attenuator
13
4.1. Definition
13
4.2. Design Parameters
13
4.3. Materials
13
4.4. Design
13
4.5. Manufacturing
15
4.6. Testing
15
Composite Muffler
19
5.1. Design
19
5.2. Filament Winding
19
5.3. Manufacturing
20
Composite Rods
22
6.1. Pultrusion
22
3.
4.
5.
6.
i
6.2. Design
22
6.3. Manufacturing
22
Release Agent Testing
24
7.1. General Method of Manufacturing
24
7.2. Reason for Testing
24
7.3. Conclusion
24
Seat
25
8.1. Design based on ergonomics
25
8.2. Manufacturing
25
Battery Mount
28
9.1. Design and Manufacturing
28
Dashboard
30
10.1. Design
30
10.2. Rapid Prototyping
30
10.3. Manufacturing
30
Floor
31
11.1. Design
31
11.2. Sandwich Panels
31
11.3. Manufacturing
31
Body works
32
12.1. Design
32
12.2. Analysis
32
12.3. Manufacturing
40
13.
Conclusion
43
14.
Future Scope
44
14.1. Monocoque
44
Bibliography
45
7.
8.
9.
10.
11.
12.
15.
ii
1. LIST OF TABLES AND FIGURES
Table 1: Comparison of Metal Components and Composite Components
Figure 1: Test set-up photographs
Figure 2: Testing Data-1
Figure 3: Testing Data-2
Figure 4: Schematic diagram of Composite Muffler
Figure 5: Schematic diagram of Filament Winding
Figure 6: Components of Composite Muffler
Figure 7: Composite Muffler
Figure 8: Pultruded Rods
Figure 9: Pultruded Rod with metal insert glued
Figure 10: MDF Pattern for Seat
Figure 11: Application of wax to seat pattern for better finish
Figure 12: Layer of gel coat applied over seat
Figure 13: The finished seat
Figure 14: Mold made out of metal
Figure 15: Vacuum Bagging
Figure 16: Battery Mount
Figure 17: Performing hand layup for the floor
Figure 18: Initial design of nose
Figure 19: Flow Analysis on Ansys-1
Figure 20: Flow Analysis on Ansys-2
Figure 21: Down force v/s Time Plot-1
1
Figure 22: Down force v/s Time Plot-2
Figure 23: Down force v/s Time Plot-3
Figure 24: Second Iteration of Nose
Figure 25: Flow Analysis on Ansys-3
Figure 26: Flow Analysis on Ansys-4
Figure 27: Down force v/s Time Plot-4
Figure 28: Down force v/s Time Plot-5
Figure 29: Down force v/s Time Plot-6
Figure 30: Final Design of Nose
Figure 31: Pressure analysis on Ansys
Figure 32: Flow Analysis on Ansys-5
Figure 33: Mesh on Ansys
Figure 34: Down force v/s Time Plot-7
Figure 35: Down force v/s Time Plot-8
Figure 36: Layup over the Nose completed
Figure 37: Final painted Nose
Figure 38: Nose on the car
2
2. INTRODUCTION
2.1. Aim
Our aim was to implement composite materials successfully on various parts of a race
car. It has a myriad of benefits. We saw it as an opportunity to learn a lot about a
relatively new technology which will gain increasing significance in the modern world.
2.2. Composite Materials - A brief overview
Composite materials (also called composition materials or shortened to composites) are
materials made from two or more constituent materials with significantly different
physical or chemical properties, that when combined, produce a material with
characteristics different from the individual components. The individual components
remain separate and distinct within the finished structure.
Typical engineered composite materials include:

Composite building materials such as cements, concrete

Reinforced plastics such as fiber-reinforced polymer

Metal Composites

Ceramic Composites (composite ceramic and metal matrices)
Composite materials are generally used for buildings, bridges and structures such as
boat hulls, race car bodies, shower stalls, bathtubs, and storage tanks, imitation granite
and cultured marble sinks and countertops. The most advanced examples perform
routinely on spacecraft in demanding environments.
Composites are made up of individual materials referred to as constituent materials.
There are two main categories of constituent materials: matrix and reinforcement. At
least one portion of each type is required. The matrix material surrounds and supports
the reinforcement materials by maintaining their relative positions. The reinforcements
impart their special mechanical and physical properties to enhance the matrix
properties. A synergism produces material properties unavailable from the individual
constituent materials, while the wide variety of matrix and strengthening materials
allows the designer of the product or structure to choose an optimum combination.
Engineered composite materials must be formed to shape. The matrix material can be
introduced to the reinforcement before or after the reinforcement material is placed into
the mould cavity or onto the mould surface. The matrix material experiences a melding
event, after which the part shape is essentially set. Depending upon the nature of the
3
matrix material, this melding event can occur in various ways such as chemical
polymerization or solidification from the melted state.
A variety of molding methods can be used according to the end-item design
requirements. The principal factors impacting the methodology are the natures of the
chosen matrix and reinforcement materials. Another important factor is the gross
quantity of material to be produced. Large quantities can be used to justify high capital
expenditures for rapid and automated manufacturing technology. Small production
quantities are accommodated with lower capital expenditures but higher labor and
tooling costs at a correspondingly slower rate.
Many commercially produced composites use a polymer matrix material often called a
resin solution. There are many different polymers available depending upon the starting
raw ingredients. There are several broad categories, each with numerous variations.
The most common are known as polyester, vinyl ester, epoxy, phenolic, polyimide,
polyamide, polypropylene, PEEK, and others. The reinforcement materials are often
fibers but also commonly ground minerals. The various methods described below have
been developed to reduce the resin content of the final product, or the fiber content is
increased. As a rule of thumb, lay up results in a product containing 60% resin and 40%
fiber, whereas vacuum infusion gives a final product with 40% resin and 60% fiber
content. The strength of the product is greatly dependent on this ratio.
4
3. LITERATURE REVIEW
3.1. History
The earliest man-made composite materials were straw and mud combined to form
bricks for building construction. This ancient brick-making process was documented by
Egyptian tomb paintings. Wattle and daub is one of the oldest man-made composite
materials, at over 6000 years old. Concrete is also a composite material, and is used
more than any other man-made material in the world. As of 2006, about 7.5 billion cubic
meters of concrete are made each year—more than one cubic meter for every person
on Earth.
Woody plants, both true wood from trees and such plants as palms and bamboo, yield
natural composites that were used prehistorically by mankind and are still used widely in
construction and scaffolding.
Plywood 3400 B.C. by the Ancient Mesopotamians; gluing wood at different angles
gives better properties than natural wood
Cartonnage layers of linen or papyrus soaked in plaster dates to the First Intermediate
Period of Egypt c. 2181-2055 BC and was used for death masks
Concrete was described by Vitruvius, writing around 25 BC in his Ten Books on
Architecture, distinguished types of aggregate appropriate for the preparation of lime
mortars. For structural mortars, he recommended pozzolana, which were volcanic
sands from the sand like beds of Puteoli brownish-yellow-gray in color near Naples and
reddish-brown at Rome. Vitruvius specifies a ratio of 1 part lime to 3 parts pozzolana for
cements used in buildings and a 1:2 ratio of lime to pulvis Puteolanus for underwater
work, essentially the same ratio mixed today for concrete used at sea. Natural cementstones, after burning, produced cements used in concretes from post-Roman times into
the 20th century, with some properties superior to manufactured Portland cement.
3.2. Constituents
3.2.1. Matrices
Resins
Typically, most common polymer-based composite materials, including fiberglass,
carbon fiber, and Kevlar, include at least two parts, the substrate and the resin.
Polyester resin tends to have yellowish tint, and is suitable for most backyard projects.
Its weaknesses are that it is UV sensitive and can tend to degrade over time, and thus
generally is also coated to help preserve it. It is often used in the making of surfboards
5
and for marine applications. Its hardener is a peroxide, often MEKP (methyl ethyl ketone
peroxide). When the peroxide is mixed with the resin, it decomposes to generate free
radicals, which initiate the curing reaction. Hardeners in these systems are commonly
called catalysts, but since they do not re-appear unchanged at the end of the reaction,
they do not fit the strictest chemical definition of a catalyst.
Vinyl ester resin tends to have a purplish to bluish to greenish tint. This resin has lower
viscosity than polyester resin, and is more transparent. This resin is often billed as being
fuel resistant, but will melt in contact with gasoline. This resin tends to be more resistant
over time to degradation than polyester resin, and is more flexible. It uses the same
hardeners as polyester resin (at a similar mix ratio) and the cost is approximately the
same.
Epoxy resin is almost totally transparent when cured. In the aerospace industry, epoxy
is used as a structural matrix material or as structural glue.
Shape memory polymer (SMP) resins have varying visual characteristics depending on
their formulation. These resins may be epoxy-based, which can be used for auto body
and outdoor equipment repairs; cyanate-ester-based, which are used in space
applications; and acrylate-based, which can be used in very cold temperature
applications, such as for sensors that indicate whether perishable goods have warmed
above a certain maximum temperature. These resins are unique in that their shape can
be repeatedly changed by heating above their glass transition temperature (Tg). When
heated, they become flexible and elastic, allowing for easy configuration. Once they are
cooled, they will maintain their new shape. The resins will return to their original shapes
when they are reheated above their Tg. The advantage of shape memory polymer
resins is that they can be shaped and reshaped repeatedly without losing their material
properties. These resins can be used in fabricating shape memory composites.
Other matrices
Common matrices include mud (wattle and daub), cement (concrete), polymers (fiber
reinforced plastics), metals and ceramics. Road surfaces are often made from asphalt
concrete which uses bitumen as a matrix. Unusual matrices such as ice are sometime
proposed as in pykecrete.
3.2.2. Reinforcement
Fiber
Differences in the way the fibers are laid out give different strengths and ease of
manufacture
6
Reinforcement usually adds rigidity and greatly impedes crack propagation. Thin fibers
can have very high strength, and provided they are mechanically well attached to the
matrix they can greatly improve the composite's overall properties.
Fiber-reinforced composite materials can be divided into two main categories normally
referred to as short fiber-reinforced materials and continuous fiber-reinforced materials.
Continuous reinforced materials will often constitute a layered or laminated structure.
The woven and continuous fiber styles are typically available in a variety of forms, being
pre-impregnated with the given matrix (resin), dry, uni-directional tapes of various
widths, plain weave, harness satins, braided, and stitched.
The short and long fibers are typically employed in compression molding and sheet
molding operations. These come in the form of flakes, chips, and random mate (which
can also be made from a continuous fiber laid in random fashion until the desired
thickness of the ply / laminate is achieved).
Common fibers used for reinforcement include glass fibers, carbon fibers, cellulose
(wood/paper fiber and straw) and high strength polymers for example aramid.
Other Reinforcement
Concrete uses aggregate, and reinforced concrete additionally uses steel bars (rebar) to
tension the concrete. Steel mesh or wires are also used in some glass and plastic
products.
Cores
Many composite layup designs also include a co-curing or post-curing of the prepreg
with various other mediums, such as honeycomb or foam. This is commonly called a
sandwich structure. This is a more common layup process for the manufacture of
radomes, doors, cowlings, or non-structural parts.
Open- and closed-cell-structured foams like polyvinylchloride, polyurethane,
polyethylene or polystyrene foams, balsa wood, syntactic foams, and honeycombs are
commonly used core materials. Open- and closed-cell metal foam can also be used as
core materials.
3.3. Fabrication Methods
Fabrication usually involves wetting or mixing or saturating the reinforcement with the
matrix, and then causing the matrix to bind together (with heat or a chemical reaction)
into a rigid structure. The operation is usually done in an open or closed forming mold,
but the order and ways of introducing the ingredients varies considerably.
7
3.3.1. Mold overview
Within a mold, the reinforcing and matrix materials are combined, compacted, and
cured (processed) to undergo a melding event. After the melding event, the part shape
is essentially set, although it can deform under certain process conditions. For a
thermoset polymeric matrix material, the melding event is a curing reaction that is
initiated by the application of additional heat or chemical reactivity such as an organic
peroxide. For a thermoplastic polymeric matrix material, the melding event is a
solidification from the melted state. For a metal matrix material such as titanium foil, the
melding event is a fusing at high pressure and a temperature near the melting point.
For many molding methods, it is convenient to refer to one mould piece as a "lower"
mould and another mould piece as an "upper" mould. Lower and upper refer to the
different faces of the molded panel, not the mould's configuration in space. In this
convention, there is always a lower mould, and sometimes an upper mould. Part
construction begins by applying materials to the lower mould. Lower mould and upper
mould are more generalized descriptors than more common and specific terms such as
male side, female side, a-side, b-side, tool side, bowl, hat, mandrel, etc. Continuous
manufacturing processes use a different nomenclature.
The molded product is often referred to as a panel. For certain geometries and material
combinations, it can be referred to as a casting. For certain continuous processes, it can
be referred to as a profile.
3.3.2. Vacuum bag molding
Vacuum bag molding uses a flexible film to enclose the part and seal it from outside air.
A vacuum is then drawn on the vacuum bag and atmospheric pressure compresses the
part during the cure process. Vacuum bag material is available in a tube shape or a
sheet of material. When a tube shaped bag is used, the entire part can be enclosed
within the bag. When using sheet bagging materials, the edges of the vacuum bag are
sealed against the edges of the mould surface to enclose the part against an air-tight
mould. When bagged in this way, the lower mold is a rigid structure and the upper
surface of the part is formed by the flexible membrane vacuum bag. The flexible
membrane can be a reusable silicone material or an extruded polymer film. After sealing
the part inside the vacuum bag, a vacuum is drawn on the part (and held) during cure.
This process can be performed at either ambient or elevated temperature with ambient
atmospheric pressure acting upon the vacuum bag. A vacuum pump is typically used to
draw a vacuum. An economical method of drawing a vacuum is with a venturi vacuum
and air compressor. A vacuum bag is a bag made of strong rubber-coated fabric or a
polymer film used to compress the part during a cure or hardening process. In some
applications the bag encloses the entire material, or in other applications a mold is used
8
to form one face of the laminate with the bag being a single layer to seal to the outer
edge of the mold face. When using a tube shaped bag, the ends of the bag are sealed
and the air is drawn out of the bag through a nipple using a vacuum pump. As a result,
uniform pressure approaching one atmosphere is applied to the surfaces of the object
inside the bag, holding parts together while the adhesive cures. The entire bag may be
placed in a temperature-controlled oven, oil bath or water bath and gently heated to
accelerate curing. Vacuum bagging is widely used in the composites industry as well.
Carbon fiber fabric and fiberglass, along with resins and epoxies are common materials
laminated together.
3.3.3. Pressure bag molding
This process is related to vacuum bag molding in exactly the same way as it sounds. A
solid female mould is used along with a flexible male mould. The reinforcement is
placed inside the female mould with just enough resin to allow the fabric to stick in place
(wet layup). A measured amount of resin is then liberally brushed indiscriminately into
the mould and the mould is then clamped to a machine that contains the male flexible
mould. The flexible male membrane is then inflated with heated compressed air or
possibly steam. The female mould can also be heated. Excess resin is forced out along
with trapped air. This process is extensively used in the production of composite
helmets due to the lower cost of unskilled labor. Cycle times for a helmet bag molding
machine vary from 20 to 45 minutes, but the finished shells require no further curing if
the moulds are heated.
3.3.4. Autoclave molding
A process using a two-sided mould set that forms both surfaces of the panel. On the
lower side is a rigid mould and on the upper side is a flexible membrane made from
silicone or an extruded polymer film such as nylon. Reinforcement materials can be
placed manually or robotically. They include continuous fiber forms fashioned into textile
constructions. Most often, they are pre-impregnated with the resin in the form of prepreg
fabrics or unidirectional tapes. In some instances, a resin film is placed upon the lower
mould and dry reinforcement is placed above. The upper mould is installed and vacuum
is applied to the mould cavity. The assembly is placed into an autoclave. This process is
generally performed at both elevated pressure and elevated temperature. The use of
elevated pressure facilitates a high fiber volume fraction and low void content for
maximum structural efficiency.
3.3.5. Resin Transfer Molding (RTM)
RTM is a process using a rigid two-sided mould set that forms both surfaces of the
panel. The mould is typically constructed from aluminum or steel, but composite molds
9
are sometimes used. The two sides fit together to produce a mould cavity. The
distinguishing feature of resin transfer molding is that the reinforcement materials are
placed into this cavity and the mould set is closed prior to the introduction of matrix
material. Resin transfer molding includes numerous varieties which differ in the
mechanics of how the resin is introduced to the reinforcement in the mould cavity.
These variations include everything from the RTM methods used in Out of Autoclave
Composite Manufacturing for High-Tech aerospace components to vacuum infusion (for
resin infusion see also boat building) to vacuum assisted resin transfer molding
(VARTM). This process can be performed at either ambient or elevated temperature.
3.3.6. Other fabrication methods
Other types of fabrication include press molding, transfer molding, pultrusion molding,
filament winding, casting, centrifugal casting, continuous casting and slip forming. There
are also forming capabilities including CNC filament winding, vacuum infusion, wet layup, compression molding, and thermoplastic molding, to name a few. The use of curing
ovens and paint booths is also needed for some projects.
3.4. Finishing methods
The finishing of the composite parts is also critical in the final design. Many of these
finishes will include rain-erosion coatings or polyurethane coatings.
3.5. Tooling
The mold and mold inserts are referred to as "tooling." The mold/tooling can be
constructed from a variety of materials. Tooling materials include invar, steel, aluminum,
reinforced silicone rubber, nickel, and carbon fiber. Selection of the tooling material is
typically based on, but not limited to, the coefficient of thermal expansion, expected
number of cycles, end item tolerance, desired or required surface condition, method of
cure, glass transition temperature of the material being molded, molding method, matrix,
cost and a variety of other considerations.
3.6. Physical Properties
The physical properties of composite materials are generally not isotropic (independent
of direction of applied force) in nature, but rather are typically anisotropic (different
depending on the direction of the applied force or load). For instance, the stiffness of a
composite panel will often depend upon the orientation of the applied forces and/or
moments. Panel stiffness is also dependent on the design of the panel. For instance,
10
the fiber reinforcement and matrix used, the method of panel build, thermoset versus
thermoplastic, type of weave, and orientation of fiber axis to the primary force.
In contrast, isotropic materials (for example, aluminum or steel), in standard wrought
forms, typically have the same stiffness regardless of the directional orientation of the
applied forces and/or moments.
The relationship between forces/moments and strains/curvatures for an isotropic
material can be described with the following material properties: Young's Modulus, the
shear Modulus and the Poisson's ratio, in relatively simple mathematical relationships.
For the anisotropic material, it requires the mathematics of a second order tensor and
up to 21 material property constants. For the special case of orthogonal isotropy, there
are three different material property constants for each of Young's Modulus, Shear
Modulus and Poisson's ratio—a total of 9 constants to describe the relationship between
forces/moments and strains/curvatures.
Techniques that take advantage of the anisotropic properties of the materials include
mortise and tenon joints (in natural composites such as wood) and Pi Joints in synthetic
composites.
3.7. Failure
Shock, impact, or repeated cyclic stresses can cause the laminate to separate at the
interface between two layers, a condition known as delamination. Individual fibers can
separate from the matrix e.g. fiber pull-out. Composites can fail on the microscopic or
macroscopic scale. Compression failures can occur at both the macro scale or at each
individual reinforcing fiber in compression buckling. Tension failures can be net section
failures of the part or degradation of the composite at a microscopic scale where one or
more of the layers in the composite fail in tension of the matrix or failure of the bond
between the matrix and fibers.
Some composites are brittle and have little reserve strength beyond the initial onset of
failure while others may have large deformations and have reserve energy absorbing
capacity past the onset of damage. The variations in fibers and matrices that are
available and the mixtures that can be made with blends leave a very broad range of
properties that can be designed into a composite structure. The best known failure of a
brittle ceramic matrix composite occurred when the carbon-carbon composite tile on the
leading edge of the wing of the Space Shuttle Columbia fractured when impacted during
take-off. It led to catastrophic break-up of the vehicle when it re-entered the Earth's
atmosphere on 1 February 2003.Compared to metals, composites have relatively poor
bearing strength.
11
3.8. Testing
To aid in predicting and preventing failures, composites are tested before and after
construction. Pre-construction testing may use finite element analysis (FEA) for ply-byply analysis of curved surfaces and predicting wrinkling, crimping and dimpling of
composites. Materials may be tested after construction through several nondestructive
methods including ultrasonics, thermography, shearography and X-ray radiography.
12
4. IMPACT ATTENUATOR
4.1. Definition
An impact attenuator, also known as a crash cushion, crash attenuator, or cowboy
cushions, is a device intended to reduce the damage to structures, vehicles, and
motorists resulting from a motor vehicle collision. Impact attenuators are designed to
absorb the colliding vehicle's kinetic energy.
4.2. Design Parameters
We have designed an impact attenuator based on the following parameters:
The Impact Attenuator, when mounted on the front of a vehicle with a total mass of 300
kg and run into a solid, non-yielding impact barrier with a velocity of impact of 7.0
meters/second, would give an average deceleration of the vehicle not to exceed 20 g’s,
with a peak deceleration less than or equal to 40 g’s. Total energy absorbed must meet
or exceed 7350 Joules.
4.3. Materials
We chose to select Rohacell IG-71 foam due to its excellent energy absorption
properties.
ROHACELL® IG and ROHACELL® IG-F products are closed-cell rigid foams based on
polymethacrylimide (PMI) chemistry, which do not contain any CFC's.
Its mechanical properties are as follows:
Density: 75 kg/m3
Compressive Strength: 1.5 MPa
Tensile Strength: 2.8 MPa
Shear Strength: 1.3 MPa
Elastic Modulus: 92 MPa
Shear Modulus: 29 MPa
4.4. Design
We decided to design the impact attenuator based on the drop test method. According
to this method, we could drop a mass of 300 kg on the designed impact attenuator at an
impact velocity of 7m/s to produce an energy absorbing effect of 7350J.
13
Notations
G = Ratio
a = Deceleration
g = Acceleration due to gravity
W = Weight of impact object
h = Drop height
s = Stopping Distance
V = Velocity
PE = Potential Energy
KE = Kinetic Energy
Fdyn=Dynamic force
fcr= Crushing strength
Acr= Crushed impact area
Now,
G=a/g
PE = W (h+s)
KE = 0.5 * W * V2 / g
Fdyn = fcr * Acr
Now, kinetic energy absorbed by the impact attenuator is equal to the potential energy
of the impact object
Thus,
W ( h + s ) = fcr * Acr * s
V = (2 * g * h )0.5
Thus, we get h = 2.4976m
Considering various geometries, we finalized the final geometry to be 4 cuboids having
dimensions as follows:
14
1) 225*225*50 mm3
2) 200*150*50 mm3
3) 200*150*50 mm3
4) 200*100*50 mm3
4.5. Manufacturing
The cuboids were cut to shape accurately and glued together using Araldite as an
adhesive.
4.6. Testing
The impact attenuator was tested at the ARAI (Automotive Research Association of
India) in Pune. The test results are shown in the following pages.
15
Figure 1: Test Set-up Photographs
16
Figure 2: Testing Data-1
17
Figure 3: Testing Data-2
18
5. COMPOSITE MUFFLER
5.1. Design
To save weight we decided to utilize filament wound tubes as an outer covering for the
muffler. Also the glass fiber is a bad conductor of heat. The only design problem we
could have was the resin burning up. This could be mitigated by ensuring the
temperature would not go up to over 200°C at the outer surface.
Figure 4: Schematic diagram of composite muffler
5.2. Filament Winding
Figure 5: Schematic diagram for Filament Winding
19
Filament winding is a fabrication technique for manufacturing composite material,
usually in the form of cylindrical structures. The process involves winding filaments
under varying amounts of tension over a male mould or mandrel. The mandrel rotates
while a carriage moves horizontally, laying down fibers in the desired pattern. The most
common filaments are carbon or glass fiber and are coated with synthetic resin as they
are wound. Once the mandrel is completely covered to the desired thickness, the
mandrel is placed in an oven to solidify (set) the resin. Once the resin has cured, the
mandrel is removed, leaving the hollow final product.
Filament winding is well suited to automation, where the tension on the filaments can be
carefully controlled. Filaments that are applied with high tension results in a final product
with higher rigidity and strength; lower tension results in more flexibility. The orientation
of the filaments can also be carefully controlled so that successive layers are plied or
oriented differently from the previous layer. The angle at which the fiber is laid down will
determine the properties of the final product. A high angle "hoop" will provide crush
strength, while a lower angle pattern (known as a closed or helical) will provide greater
tensile strength.
5.3. Manufacturing
Thus, as we see below the tube manufactured by filament winding is fitted over the
perforated metal tubes along with aluminum caps. Glass wool is placed in between to
ensure insulation.
Figure 6: Components of Composite Muffler
20
Figure 7: Composite Muffler
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6. COMPOSITE RODS
6.1. Pultrusion
Pultrusion is a continuous process for manufacture of composite materials with constant
cross-section. Reinforced fibers are pulled through a resin, possibly followed by a
separate preforming system, and into a heated die, where the resin undergoes
polymerization. Many resin types may be used in pultrusion including polyester,
polyurethane, vinyl ester and epoxy.
The technology is not limited to thermosetting polymers. More recently, pultrusion has
been successfully used with thermoplastic matrices such as polybutylene terephthalate
(PBT), polyethylene terephthalate (PET) either by powder impregnation of the glass
fiber or by surrounding it with sheet material of the thermoplastic matrix, which is then
heated.
Ecological cleanness of manufactured products, in contrast to composites on
thermosetting resins base, as well as practically unlimited possibilities of recycling
(processing) after the resource depletion appear to be forcible arguments in favor of
reinforced thermoplastics. For these reasons the industrial output and use of the given
materials in highly industrialized countries have increased by 8-10% per year in recent
decades.
Pultrusion technology of manufacturing of fiber composites with polymer matrix appears
to be energy-efficient and resource-saving.
Economic and environmental factors favor use of a thermoplastic matrix, but due to the
high viscosity of melts it is difficult to achieve high productivity and high quality of
fiberfills impregnation with this type of matrix.
6.2. Design
We decided to implement pultruded rods into the manufacture of rods for various
components such as A-arms of suspension and tie rods of steering. We would require
perfecting the art of using adhesives for the same.
6.3. Manufacturing
We had six failed attempts before we could successfully glue the metal inserts to the
pultruded rod and make it withstand a load of 20,000 N.
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Figure 8: Pultruded Rods
Figure 9: Pultruded Rod with metal insert glued
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7. RELEASE AGENT TESTING
7.1. General Method of Manufacturing
Generally when we manufacture parts using fiber reinforced plastics, it is a three step
process. First, the pattern is made out of mild density foam (MDF). Then, a mould is
made from the pattern out of glass fiber and resin-hardener. Finally the final part is
removed from this glass fiber mould.
7.2. Reason for testing
As it is seen, this is a very time-consuming process. Further, it is not quite economical.
Thus, we decided to eliminate the mould completely.
Initially, we tried to use the pattern directly to make the final piece. However, while
performing hand lay-up, the resin hardener mixture seeped into the MDF due to its
permeability. Due to this reason, while releasing the part, a section of the MDF came
out along with it. This was a failure.
The next time, we tried using a silicon based release agent to perform our task.
However, this was another unsuccessful trial.
Finally with the help of a company (Magnus Composites) we were able to find a solution
to this.
7.3. Conclusion
We discovered that a perfect mixture of quick curing resin-hardener and a special
sealant performed our task perfectly. We finally got the result we were hoping for.
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8. SEAT
8.1. Design based on ergonomics
We focused on designing the seat of the car to make it extremely comfortable for the
driver. Hence, while designing the seat, we took into account the various comfort zones
of drivers. We measured the various parameters of comfort based on the inputs of 6
different drivers seated in driving positions. To provide stiffening as well as cushioning
effect, we decided to utilize foam for support.
8.2. Manufacturing
The seat was manufactured like all other components. We made a pattern out of MDF
and made it as smooth as possible keeping in mind the principle that the smoother the
pattern, the smoother the mould, the smoother the final piece. To provide additional
shine and superior finish, we incorporated gel coat to our general hand layup process.
Figure 10: MDF Pattern for Seat
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Figure 11: Application of wax to the seat pattern for better finish
Figure 12: Layer of gel coat applied over seat
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Figure 13: The finished seat
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9. BATTERY MOUNT
9.1. Design and Manufacturing
For making the mould, we utilized a metal block and metal cylinders cut into half in a
plane along its axis. These were glued onto the block. The final lay-up was performed
on this.
Figure 14: Mold made out of metal
Figure 15: Vacuum Bagging
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Figure 16: Battery Mount
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10. DASHBOARD
10.1. Design
The major considerations in the design of the dashboard were sturdiness and great
looks. We decided to have a curved shape for a much classier looking dashboard.
However, making a mould for that shape was a difficult process. Hence, we decided to
adopt rapid prototyping to make the mould.
10.2. Rapid Prototyping
Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a
physical part or assembly using three-dimensional computer aided design (CAD) data.
Construction of the part or assembly is usually done using 3D printing technology.
Additive manufacturing or 3D printing is a process of making a three-dimensional solid
object of virtually any shape from a digital model. 3D printing is achieved using an
additive process, where successive layers of material are laid down in different shapes.
3D printing is considered distinct from traditional machining techniques, which mostly
rely on the removal of material by methods such as cutting or drilling (subtractive
processes). A materials printer usually performs 3D printing processes using digital
technology.
10.3. Manufacturing
Once we obtained the rapid prototyped mould. We performed hand lay up on the mould
to get the final dashboard.
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11. FLOOR
11.1. Design
The floor was designed keeping in mind that it was exposed to forces equivalent to the
weight of a human body. To account for this, we decided to implement sandwich panels.
11.2. Sandwich Panels
We decided to utilize a sandwich made up of high density structural foam at the centre
and layers of glass fiber reinforced with resin and hardener on either side.
11.3. Manufacturing
The manufacturing was done in the same way as previous parts. Only in this case there
were minor difficulties encountered due to the stiffness of the foam.
Figure 17: Performing hand lay-up for the floor
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12. BODY WORKS
12.1. Design
The bodyworks include the nose and the side panels. The side panels were to be
utilized for the basic purpose of covering the chassis. Hence they were simply
reinforced glass fiber plates. However, the nose had an important part to play
aerodynamically. Hence, we decided to perform a finite element analysis in this case.
12.2. Analysis
1st iteration
Figure 18: Initial design of nose
Figure 19: Flow Analysis on Ansys-1
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Figure 20: Flow Analysis on Ansys-2
Figure 21: Down force v/s Time plot-1
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Figure 22: Down force v/s Time plot-2
Figure 23: Down force v/s Time plot-3
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2nd iteration
Figure 24: Second iteration of nose
Figure 25: Flow Analysis on Ansys-3
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Figure 26: Flow Analysis on Ansys-4
Figure 27: Down force v/s Time plot-4
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Figure 28: Down force v/s Time plot-5
Figure 29: Down force v/s Time plot-6
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3rd iteration: 2013 final design
Figure 30: Final design of Nose
Figure 31: Pressure Analysis on Ansys
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Figure 32: Flow Analysis on Ansys-5
Figure 33: Mesh on Ansys
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Figure 34: Down force v/s Time plot-7
Figure 35: Down force v/s Time plot-8
12.3. Manufacturing
The manufacturing was performed in the same manner as that of the seat.
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Figure 36: Layup over the nose completed
Figure 37: Final painted nose
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Figure 38: Nose on the car
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13. CONCLUSION
Table 1: Comparison of metal components and composite components
Component
Weight of Metal Part
Weight of Composite Part
Muffler
5.6 kg
3.2 kg
Rods
8.3 kg
4.8 kg
Seat
6.3 kg
3.7 kg
Body works
8.9 kg
4.7 kg
Floor
3.0 kg
1.5 kg
Battery Mount
0.9 kg
0.4 kg
Dashboard
0.6 kg
0.3 kg
Total Weight Reduction = 15 kg
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14. FUTURE SCOPE
14.1. Monocoque
Monocoque is a structural approach that supports loads through an object's external
skin, similar to a ping pong ball or egg shell. The term is also used to indicate a form of
vehicle construction in which the skin provides the main structural support, although this
is rare and is usually confused with either semi-monocoque or a unibody. The word
monocoque comes from the Greek for single (mono) and French for shell (coque). The
technique may also be called structural skin or stressed skin.
The zenith of the usage of composite materials is in the successful implementation of a
monocoque chassis.
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15. BIBLIOGRAPHY
1. www.wikipedia.org
2. www.rohacell.com
3. “Tune to Win” by Carroll Smith
4. Fiber Glass and Composite Materials by Forbes Aird
5. Composites for Construction by Lawrence Bank
6. Mechanics of Composite Structures - L. Kollar, G. Springer (Cambridge, 2003)
WW
7. Novikov - Concise Dictionary of Materials Science [CRC 1999] 4AH
8. www.fsae.com/groupee
9. SAE Papers
10. Composite materials handbook
11. Structural Laminates-Composites for Space Applications
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