MANUFACTURING AND MECHANICAL TESTING

OF COMPOSITE DRIVE SHAFT

PHASE I REPORT

Submitted by

LOGANATHAN.G(612613402009)

in partial fulfillment for the award of the degree of

MASTER OF ENGINEERING

in

CAD/CAM

DEPARTMENT OF MECHANICAL ENGINEERING

THE KAVERY COLLEGE OF ENGINEERING

MECHERI – 636 453

ANNA UNIVERSITY:: CHENNAI 600 025

JUNE – 2015

ABSTRACT

Substituting composite structures for conventional metallic structures have many advantages because of higher specific stiffness and structure of composite materials. This work deals with the replacement of conventional steel drive shaft with e-glass/epoxy, composite drive shaft for an automotive applications, advanced composite materials seem ideally suited for long, power drive shaft (propeller applications). The charpy test, izod test and compression test are taken in different combination of e-glass/epoxy composite like 30%- e-glass/70%-epoxy, 60%- e-glass/40%-epoxy, 50%- e-glass/50%-epoxy, 70%- e-glass/30%-epoxy are tested above mentioned. Regarding the testing result, it is possible to achievethe replacement. Minimize the weight of composite drive shaft also achieved without increase in cost and without decrease in quality.

KEYWORDS: E-Glass/Epoxy, Charpy, Izod and compression test.

CHAPTER 1

INTRODUCTION

The advanced composite materials such as Graphite, Carbon, Kevlar and Glass with

suitable resins are widely used because of their high specific strength

(strength/density) and high specific modulus (modulus/density). Advanced composite

materials seem ideally suited for long, power driver shaft (propeller shaft)

applications. Their elastic properties can be tailored to increase the torque they can

carry as well as the rotational speed at which they operate. The drive shafts are used in

automotive applications. The automotive industry is exploiting composite material

technology for structural components construction in order to obtain the reduction of

the weight without decrease in vehicle quality and reliability. The weight reduction of

the drive shaft can have a certain role in the general weight reduction of the vehicle

and is a highly desirable goal, if it can be achieved without increase in cost and

decrease in quality and reliability. It is known that energy conservation is one of the

most important objectives in vehicle design and reduction of weight is one of the most

effective measures to obtain this result. Actually, there is almost a direct

proportionality between the weight of a vehicle and its fuel consumption, particularly

in city driving. The vehicle propeller shaft is shown in figure 1.1

Figure 1.1 Vehicle Drive Shaft

1.1 Overview of Composites

The advantage of composite materials over conventional materials stem largely from

their higher specific strength, stiffness and fatigue characteristics, which enables

structural design to be more versatile. By definition, composite materials consist of

two or more constituents with physically separable phases (Mueller et al, 2003).

However, only when the composite phase materials have notably different physical

properties it is recognized as being a composite material. Composites are materials

that comprise strong load carrying material (known as reinforcement) imbedded in

weaker material (known as matrix).Reinforcement provides strength and rigidity,

helping to support structural load. The matrix or binder (organic or inorganic)

maintains the position and orientation of the reinforcement. Significantly, constituents

of the composites retain their individual, physical and chemical properties; yet

together they produce a combination of qualities which individual constituents would

be incapable of producing alone. The reinforcement may be platelets, particles or

fibers and are usually added to improve mechanical properties such as stiffness,

strength and toughness of the matrix material. Long fibers that are oriented in the

direction of loading offer the most efficient load transfer. This is because the stress

transfer zone extends only over a small part of the fiber-matrix interface and

perturbation effects at fiber ends may be neglected. In other words, the ineffective

fiber length is small. Popular fibers available as continuous filaments for use in high

performance composites are glass, carbon and aramid fibers.

1.1.1 Types of Composites

For the sake of simplicity, however, composites can be grouped into categories based

on the nature of the matrix each type possesses (Misra et al, 2005). Methods of

fabrication also vary according to physical and chemical properties of the matrices

and reinforcing fibers.

1.1.2 Metal Matrix Composites (MMCs)

Metal matrix composites, as the name implies, have a metal matrix. Examples of

matrices in such composites include aluminum, magnesium and titanium. The typical

fiber includes carbon and silicon carbide. Metals are mainly reinforced to suit the

needs of design. For example, the elastic stiffness and strength of metals can be

increased, while large co-efficient of thermal expansion, and thermal and electrical

conductivities of metals can be reduced by the addition of fibers such as silicon

carbide.

1.1.3 Ceramic Matrix Composites (CMCs)

Ceramic matrix composites have ceramic matrix such as alumina, calcium, alumino

silicate reinforced by silicon carbide. The advantages of CMC include high strength,

hardness, high service temperature limits for ceramics, chemical inertness and low

density. Naturally resistant to high temperature, ceramic materials have a tendency to

become brittle and to fracture. Composites successfully made with ceramic matrices

are reinforced with silicon carbide fibers. These composites offer the same high

temperature tolerance of super alloys but without such a high density. The brittle

nature of ceramics makes composite fabrication difficult. Usually most CMC

production procedures involve starting materials in powder form. There are four

classes of ceramics matrix glass (easy to fabricate because of low softening

temperatures, include borosilicate and alumino silicates), conventional ceramics

(silicon carbide, silicon nitride, aluminum oxide and zirconium oxide are fully

crystalline), cement and concreted carbon components.

1.1.4 Polymer Matrix Composites (PMCs)

The most common advanced composites are polymer matrix composites. These

composites consist of a polymer thermoplastic or thermosetting reinforced by fiber

(natural carbon or boron). These materials can be fashioned into a variety of shapes

and sizes. They provide great strength and stiffness along with resistance to

corrosion. The reason for these being most common is their low cost, high strength

and simple manufacturing principles. Due to the low density of the constituents the

polymer composites often show excellent specific properties.

1.2 Natural Fiber Composites

Fiber-reinforced polymer composites have played a dominant role for a long time in a

variety of applications for their high specific strength and modulus. The manufacture,

use and removal of traditional fiber–reinforced plastic, usually made of glass, carbon

or aramid fibers–reinforced thermoplastic and thermoset resins are considered

critically because of environmental problems. By natural fiber composites we mean a

composite material that is reinforced with fibers, particles or platelets from natural or

renewable resources, in contrast to for example carbon or aramid fibers that have to

be synthesized. Natural fibers include those made from plant, animal and mineral

sources. Natural fibers can be classified according to their origin. The detailed

classification is shown in Figure 1.2

Figure 1.2 Classification of Natural Fibers

1.2.1 Animal Fiber

Animal fiber generally comprise proteins; examples mohair, wool, silk, alpaca,

angora. Animal hair (wool or hair) are the fibers taken from animals or hairy

mammals. E.g. Sheep’s wool, goat hair (cashmere, mohair) alpaca hair, horse hair,

etc., silk fiber are the fibers collected from dried saliva of bugs or insects during the

preparation of cocoons. Examples include silk from silk worms. Avian fiber is the

fibers from birds, e.g. feathers and feather fiber.

Natural Fibers

Animal Fibers Mineral Fibers Plant Fibers

Silk fiber

Avian fiber

Animal hair

Asbestos

Ceramic fibers

Metal fibers

Seed fiber

Leaf fiber

Skin fiber

Fruit fiber

Stalk fiber

1.2.2 Mineral Fiber

Mineral fibers are naturally occurring fiber or slightly modified fiber procured from

minerals. These can be categorized into the following categories. Asbestos is the

only naturally occurring mineral fiber. Variations are serpentine and amphiboles,

anthophyllite. Ceramic fibers includes glass fibers (Glass wood and Quartz),

aluminium oxide, silicon carbide, and boron carbide. Metal fibers include

aluminium fibers.

1.2.3 Plant Fiber

Plant fibers are generally comprised mainly of cellulose: examples include cotton,

jute, flax, ramie, sisal and hemp. Cellulose fibers serve in the manufacture of paper

and cloth. This fiber can be further categorizes into following as seed fiber are the

fibers collected from the seed and seed case e.g. cotton and kapok. Leaf fiber are the

fibers collected from the leaves e.g. sisal and agave. Skin fiber is the fibers are

collected from the skin or best surrounding the stem of their respective plant. These

fibers have higher tensile strength than other fibers. Therefore, these fibers are used

for durable yarn, fabric, packaging, and paper. Some examples are flax, jute,

banana, hemp, and soybean. Tree wood is also such a fiber. Natural fiber composites

are by no means new to mankind. Already the ancient Egyptians used clay that was

reinforced by straw to build walls. In the beginning of the 20th century wood- or

cotton fiber reinforced phenol- or melamine formaldehyde resins were fabricated

and used in electrical applications for their non-conductive and heat-resistant

properties. At present Day natural fiber composites are mainly found in automotive

and building industry and then mostly in applications where load bearing capacity

and dimensional stability under moist and high thermal conditions are of second

order importance. For example, flax fiber reinforced polyolefin are extensively used

today in the automotive industry, but the fiber acts mainly as filler material in non-

structural interior panels(Nurmi et al, 2000). Natural fiber composites used for

structural purposes do exist, but then usually with synthetic thermoset matrices

which of course limit the environmental benefits(stockman et al, 1971). Natural

fibers are generally lingo-cellulosic in nature, consisting of helically wound

cellulose micro fibrils in a matrix of lignin and hemi cellulose. According to a Food

and Agricultural Organization survey, Tanzania and Brazil produce the largest

amount of sisal. Henequen is grown in Mexico. Abaca and hemp are grown in the

Philippines. The largest producers of jute are India, China, and Bangladesh.

Presently, the annual production of natural fibers in India is about 6 million tons as

compared to worldwide production of about 25 million tons. The natural fiber

composites can be very cost effective material for following applications

Building and construction industry: panels for partition and false ceiling,

partition boards, wall, floor, window and door frames, roof tiles, which can

be used in times of natural calamities such as floods, cyclones, earthquakes,

etc.

Storage devices: post-boxes, grain storage silos, bio-gas containers, etc.

Furniture: chair, table, shower, bath units, etc.

Electric devices: electrical appliances, pipes, etc.

Everyday applications: lampshades, suitcases, helmets, etc.

Transportation: automobile and railway coach interior, boat, etc.

1.3 Important Properties of Composite Materials

1.3.1 Physical Properties

The fiber density is less than the bulk annealed value by approximately 0.04

g/cc at room temperature. The glass fiber densities used in composites range

from approximately 2.11 g/cc for D Glass to 2.72 g/cc for ECRGLAS

reinforcements.

The maximum measured strength of S-2 Glass fibers at liquid nitrogen

temperatures is 11.6 GPa for a 12.7 mm gauge length, 10 μm diameter fiber.

E Glass and S-2 Glass fibers have been found to retain approximately 50% of

their pristine room-temperature strength at 538°C (1000°F) and are compared

to organic reinforcement fibers.

The Young’s modulus of elasticity of unannealed silicate glass fibers ranges

from about 52 GPa to 87 GPa.

E Glass fibers that have been annealed to compact their atomic structure will

increase in Young’s modulus from 72 GPa to 84.7 GPa.

For most silicate glasses, Poisson’s ratio falls between 0.15 and 0.26. The

Poisson’s ratio for E Glasses is 0.22 ± 0.02 and is reported not to change with

temperature when measured up to 510°C.

1.3.2 Chemical Resistance

The chemical resistance of glass fibers to the corrosive and leaching actions of

acids, bases, and water is expressed as a percent weight loss. The lower this

value, the more resistant the glass is to the corrosive solution.

The test procedure involves subjecting a given weight of 10 micron diameter

glass fibers, without binders or sizes, to a known volume of corrosive solution

held at 96°C.

The fibers are held in the solution for the time desired and then are removed,

washed, dried, and weighed to determine the weight loss. The results reported

are for 24-hr (1 day) and 168-hr (1 week) exposures.

The corrosion rate may be influenced by the acid concentration, temperature,

fiber diameter, and the solution volume to glass mass ratio. In alkaline

environments weight loss measurements are more subjective as the alkali

affects the network and precipitates the metal oxides.

Tensile strength after exposure is a better indicator of the residual glass fiber

properties.

1.3.3 Electrical Properties

The electrical properties were measured on annealed bulk glass samples

according to the testing procedures cited.

The dielectric constant or relative permittivity is the ratio of the capacitance of

a system with the specimen as the dielectric to the capacitance of the system

with a vacuum as the dielectric. Capacitance is the ability of the material to

store an electrical charge.

Permittivity values are affected by test frequency, temperature, voltage, relative

humidity, water immersion, and weathering.

The dissipation factor is generally measured simultaneously with permittivity

measurements, and is greatly influenced by frequency, humidity, temperature,

and water immersion.

The ratio of the dielectric breakdown voltage to the specimen thickness can be

expressed as the dielectric strength in kV/cm.

Breakdown voltages are influenced by electrode geometry, specimen thickness

(because dielectric strength varies approximately as the reciprocal of the square

root of the thickness), temperature, voltage application time, voltage wave

form, frequency, surrounding medium, relative humidity, water immersion, and

directionality in laminated and inhomogeneous plastics.

1.3.4 Thermal Properties

The viscosity of a glass decreases as the temperature increases. The viscosity-

temperature plots for E Glass and S-2 Glass fibers. Note that the S-2 Glass

fibers’ temperature at viscosity is 150-260°C higher than that of E Glass, which

is why S-2 Glass fibers have higher use temperatures than E Glass.

The softening point is defined as the temperature at which glass will deform

under its own weight; it occurs at a viscosity of approximately 106.6 Pa.

The annealing point is the temperature corresponding to either a specific rate of

elongation of a glass fiber is a specific rate of midpoint deflection of a glass

beam the viscosity at the annealing point is approximately 1012Pa.

The strain point of glass, internal stresses are substantially relieved in a matter

of hours. The viscosity at the strain point is approximately 1013.5Pa.

The mean coefficient of thermal expansion over the temperature range from -

30° to 250°C. Near room temperature, the thermal conductivity for glasses

ranges from 0.55 W/m-K for lead silicate (80% lead oxide, 20% silicon

dioxide) to 1.4 W/m-K for fused silica glass.

1.3.5 Optical Properties

Refractive index is measured on either unannealed or annealed glass fibers.

The standard oil immersion techniques are used with monochromatic sodium D

light at 25°C.

In general, the corresponding annealed glass will exhibit an index that will

range from approximately 0.003 to 0.006 higher than the as-formed glass

fibers.

1.3.6 Radiation Properties

E Glass and S-2 Glass fibers have excellent resistance to all types of nuclear

radiation. Alpha and beta radiation have almost no effect, while gamma

radiation and neutron bombardment produce a 5 to 10% decrease in tensile

strength, a less than 1% decrease in density, and a slight discoloration of fibers.

Glass fibers resist radiation because the glass is amorphous, and the radiation

does not distort the atomic ordering.

Glass can also absorb a few percent of foreign material and maintain the same

properties to a reasonable degree. Also, because the individual fibers have a

small diameter, the heat of atomic distortion is easily transferred to a surface

for dispersion.

E Glass and C Glass are not recommended for use inside atomic reactors

because of their high boron content. S-2 Glass fibers are suitable for use inside

atomic reactors. Because quite a wide variety of organic products are used in

diverse radiation environments, it is usually necessary to try out most products

in simulated conditions to determine whether the organics will be satisfactory.

1.4 E-Glass Fiber

E-Glass or electrical grade glass was originally developed for standoff insulators for

electrical wiring. It was later found to have excellent fiber forming capabilities and is

now used almost exclusively as the reinforcing phase in the material commonly

known as fiberglass.

1.4.1 Fiber Manufacturing

Glass fibers are generally produced using melt spinning techniques. These involve

melting the glass composition into a platinum crown which has small holes for the

molten glass to flow. Continuous fibers can be drawn out through the holes and

wound onto spindles, while short fibers may be produced by spinning the crown,

which forces molten glass out through the holes centrifugally. Fibers are cut to length

using mechanical means or air jets. Fiber dimension and to some extent properties can

be controlled by the process variables such as melt temperature (hence viscosity) and

drawing/spinning rate. The temperature window that can be used to produce a melt of

suitable viscosity is quite large, making this composition suitable for fiber forming. As

fibers are being produced, they are normally treated with sizing and coupling agents.

These reduce the effects of fibre-fibre abrasion which can significantly degrade the

mechanical strength of the individual fibers. Other treatments may also be used to

promote wetting and adherence of the matrix material to the fiber.

1.4.2 Composition

E-Glass is a low alkali glass with a typical nominal composition of Silo2 54wt%,

Al2O3 14wt%, CaO+MgO 22wt%, B2O3 10wt% and Na2O+K2O less than 2wt%.

Some other materials may also be present at impurity levels.

1.4.3 Key Properties of E-Glass

High stiffness

Relatively low density

Non-flammable

Resistant to heat

Good chemical resistance

Relatively insensitive to moisture

Able to maintain strength properties over a wide range of conditions

Good electrical insulation

Properties for composite materials are given in table 1.1. It gives the details of few

composite materials. Units and properties of the E-Glass/Epoxy is given in table 1.2

Table 1.1 Different Type of Composite with Properties

Materials Density (Kg/m3)

Tensile Strength(N/mm2)

Young’s modulus(KN/mm2)

E-Glass 0.02452 2000 80

S-Glass 0.02442 4750 89

Alumina 0.03217 1950 297

Carbon 0.01962 2900 525

Kevlar 29 0.01412 2860 64

Kevlar 49 0.01412 3750 136

Table 1.2 properties of the E-Glass/Epoxy

.

S.NO Property Units E-Glass/ Epoxy1 E11 GPa 50.0

2 E22 GPa 12.0

3 G12 GPa 5.6

4 γ 12 -- 0.3

5 St1 = Sc

1 MPa 800.0

6 St2 = Sc

2 MPa 40.0

7 S12 MPa 72.0

8 Ρ Kg /m3 2000.0

CHAPTER 2

DRIVE SHAFT

2.1 About Drive Shaft

A drive shaft or propeller shaft is a mechanical component for transmitting torque and

rotation, usually used to connect other components of a drive train that cannot be

connected directly because of distance or the need to allow for relative movement

between them.

Drive shafts are carriers of torque they are subject to torsion and shear stress,

equivalent to the difference between the input torque and the load. They must

therefore be strong enough to bear the stress, whilst avoiding too much additional

weight as that would in turn increase their inertia. The used drive shaft is shown in

figure 2.1

2.1.1 Vehicles

An automobile may use a longitudinal shaft to deliver power from an

engine/transmission to the other end of the vehicle before it goes to the wheels. A pair

of short drive shafts is commonly used to send power from a central differential,

transmission, or transaxle to the wheels.

Figure 2.1 Drive Shaft for Research and Development (R&D)

The automotive industry also uses drive shafts at testing plants. At an engine test stand

a drive shaft is used to transfer a certain speed / torque from the combustion engine to

a dynamometer. A "shaft guard" is used at a shaft connection to protect against contact

with the drive shaft and for detection of a shaft failure. At a transmission test stand a

drive shaft connects the prime mover with the transmission.

2.1.2 Purpose of the Drive Shaft (or Propeller Shaft)

The torque that is produced from the engine and transmission must be transferred to

the rear wheels to push the vehicle forward and reverse. The drive shaft must provide

a smooth, uninterrupted flow of power to the axles. The drive shaft and differential are

used to transfer this torque.

2.2 Different Types of Shafts

2.2.1Transmission Shaft

These shafts transmit power between the source and the machines absorbing power.

The counter shafts, line shafts, overhead shafts and all factory shafts are transmission

shafts. Since these shafts carry machine parts such as pulleys, gears etc.

2.2.2 Machine Shaft

These shafts form an integral part of the machine itself. For example, the crankshaft is

an integral part of I.C.engines slider-crank mechanism.

2.2.3 Axle

A shaft is called an axle, if it is a stationary machine element and is used for the

transmission of bending moment only. It simply acts as a support for rotating bodies.

It is used to support hoisting drum, a car wheel or a rope sheave.

2.2.4 Spindle

A shaft is called a spindle, if it is a short shaft that imparts motion either to a cutting

tool or to a work-piece. It is used to drill press spindles-impart motion to cutting tool

(i.e.) drill, lathe spindles-impart motion to work-piece.

Apart from, an axle and a spindle, shafts are used at so many places and almost

everywhere wherever power transmission is required. Few of them are Automobile

Drive Shaft, Ship Propeller Shaft, and Helicopter Tail Rotor Shaft.

This list has no end, since in every machine, gearboxes, automobiles etc. shafts are

there to transmit power from one end to other.

2.3 Functions of the Drive Shaft

First, it must transmit torque from the transmission to the differential gear box.

During the operation, it is necessary to transmit maximum low-gear torque

developed by the engine.

The drive shafts must also be capable of rotating at the very fast speeds

required by the vehicle.

The drive shaft must also operate through constantly changing angles between

the transmission, the differential and the axles. As the rear wheels roll over

bumps in the road, the differential and axles move up and down. This

movement changes the angle between the transmission and the differential.

The length of the drive shaft must also be capable of changing while

transmitting torque. Length changes are caused by axle movement due to

torque reaction, road deflections, braking loads and so on. A slip joint is used

to compensate for this motion. The slip joint is usually made of an internal and

external spline. It is located on the front end of the drive shaft and is connected

to the transmission.

2.4 Drive Shaft Arrangement in a Car Model

Conventional two-piece drive shaft arrangement for rear wheel vehicle driving system

is shown in figure 2.2

Figure 2.2 Conventional Drive Shaft Arrangements for Rear Wheel Vehicle

Driving System

This hollow shaft can be designed in such a way as to minimize the amount of energy

wasted turning itself. The moment of inertia is the rotational inertia of the shaft. A

larger shaft will have a larger moment of inertia. By making the diameter larger the

moment of inertia increases.

2.5 Background

Composites consist of two or more materials or material phases that are individual

constituents. The constituents are combined at a macroscopic level and or not soluble

in each other. The main difference between composite and an alloy are constituent

materials which are insoluble in each other and the individual constituents retain those

properties in the case of composites, where as in alloys, constituent materials are

soluble in each other and forms a new material which has different properties from

their constituents.

2.5.1 Advantages of Composites Materials

The advantages of composites over the conventional materials are,

Drive system is less likely to become jammed or broken, a common problem

with chain-driven bicycles.

The use of a gear system creates a smoother and more consistent pedaling

motion.

The rider cannot become dirtied from chain grease or injured by the chain from

"Chain bite", which occurs when clothing or even a body part catches between

the chain and a sprocket.

Lower maintenance than a chain system when the drive shaft is enclosed in a

tube, the common convention.

More consistent performance. Dynamic Bicycles claims that a drive shaft

bicycle consistently delivers 94% efficiency, whereas a chain-driven bike can

deliver anywhere from 75-97% efficiency based on condition.

Greater clearance with the absence of a derailleur or other low-hanging

machinery, the bicycle has nearly twice the ground clearance.

For bicycle rental companies, a drive-shaft bicycle is less prone to be stolen,

since the shaft is non-standard, and both noticeable and non-maintainable. This

type of bicycle is in use in several major cities of Europe, where there have

been large municipal funded, public (and automatic) bicycle rental projects.

High impact resistance.

Improved corrosion resistance.

Low electrical conductivity.

2.5.2 Limitations of Composites Materials

A drive shaft system weighs more than a chain system, usually 1-2 pounds

heavier

At optimum upkeep, a chain delivers greater efficiency

Use of lightweight derailleur gears with a high number of ratios is impossible,

although hub gears can be used

Wheel removal can be complicated in some designs (as it is for some chain-

driven bicycles with hub gears).

Mechanical characterization of a composite structure is more complex than that

of a metallic structure.

The design of fiber reinforced structure is difficult compared to a metallic

structure, mainly due to the difference in properties in directions.

Rework and repairing are difficult.

They do not have a high combination of strength and fracture toughness as

compared to metals.

They do not necessarily give higher performance in all properties used for

material selection.

2.5.3 Usage of Composite Materials in Different Countries

In the technical world all countries around world are comparing with others to prove

their technical facilities available in their own country and usage is shown in figure

2.3

Figure 2.3 Usages of Composite Materials in Different Countries

2.5.4 Applications (in Field) Depends on the Performance of Composite

Composite materials are used to various purposes in various fields. Like Construction,

Automotive, Civil Aerospace, Military Aerospace, Biomedical are the fields, which

are using composite materials to reduce the weight, cost.

The usage of composite materials in the various fields is shown in the graphical

method and application chart is given below figure 2.4

Construction Automotive Civil Aerospace

Military Aerospace

Biomedical

Figure 2.4 Relative Importances on Cost and Performance in Different

Industries.

CHAPTER 3

FABRICATION OF COMPOSITE (E-GLASS/EPOXY) DRIVE SHAFT:

3.1 Drive Shaft Fabrication

Composite (E-glass/Epoxy) drive shaft is made up of hand lay-up operation. Resin is

mixed with a catalyst or hardener if working with epoxy, otherwise it will not cure

(harden) for days/weeks. Next, the mold is wetted out with the mixture. The sheets of

fiberglass are placed over the mould and rolled down into the mould using steel

rollers. The material must be securely attached to the mould; air must not be trapped

in between the fiberglass and the mould. Additional resin is applied and possibly

additional sheets of fiberglass. Rollers are used to make sure the resin is between all

the layers, the glass is wetted throughout the entire thickness of the laminate, and any

air pockets are removed. The work must be done quickly enough to complete the job

before the resin starts to cure. Various curing times can be achieved by altering the

amount of catalyst employed. It is important to use the correct ratio of catalyst to resin

to ensure the correct curing time. 1% catalyst is a slow cure, 2% is the recommended

ratio, and 3% will give a fast cure. Adding more than 4% may result in the resin

failing to cure at all. To finish the process, a weight is applied from the top to press

out any excess resin and trapped air. Stops (like coins) are used to maintain the

thickness which the weight could otherwise compress beyond the desired limit.

Other types of molding 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 lay-up, compression molding, and thermoplastic molding, to name a

few. The use of curing ovens and paint booths is also needed for some projects.

Manufacturing of composite drive shaft die is shown in figure 3.1

Figure 3.1 Die for Fabrication

There are several things to consider when picking a fabrication method. Time is a

major consideration. There is little time for fabrication, so the fabrication process has

to be quick. The fiber has to be laid at specific angles to give the shaft certain

characteristics. The weave patterns have to be tight and compact. Resin has to be

applied evenly. The shaft has to be wound in a way such that the yokes can be easily

attached. The easiest fabrication method for creating a hollow tube is filament

winding. Filament winding is an automated process in which a filamentary yarn in the

form of tow is wetted by resin and uniformly and regularly wound about a rotating

mandrel. The filament winder can be programmed to create specific and tightly wound

patterns.

To create a composite part on the winder, a winding pattern is needed, along with a

mandrel, mold release, fiber, resin and hardener, a way to apply even pressure to the

part and a curing procedure. The wind patterns were determined by using Laminate

Design software created by Dr. Larry Peel. After entering mechanical properties for

the resin and tow, different wind angles and layers were tried in the Laminate Design

software until the driveshaft had the desired characteristics.

Fabrication process of shaft is shown in figure 3.2

Figure 3.2 Fabrication Process

The resin and hardener were chosen for several reasons. First, the resin is tough.

Therein also has a high viscosity. High viscosity is desired because, with the wet

winding process, is easier to control the amount of resin being applied to the tow. Wet

winding will be discussed further in the process section. Another reason for choosing

this resin is its elongation at break. At 6% elongation at break, it is known that the

resin will not be too brittle and that the wound shaft will have some flex for absorbing

the shock between shifting gears. Finally this resin was chosen because of its high pot

life. After mixing the resin and hardener, there is a little over two hours before it

begins to gel. This is enough time to wind the entire shaft before the resin sets up.

The adhesive was chosen for a few reasons. Foremost, the adhesive also met the

criteria for high tensile lap shear strength at room and elevated temperatures. At room

temperature the adhesive has lap shear strength of 4,200 psi. At 250 F the lap shear

strength is 2,300 psi. Also, the adhesive is aerospace grade, ensuring high quality.

Once the winding begin, it became obvious that there was not enough turn around

room. When winding a composite part, there are four defined areas on the part.