Major Project Document

7/27/2019 Major Project Document

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ABSTRACT

In this work the composite laminates of Epoxy/E-glass fiber

hybridizing with and without E- glass powder are prepared for testing.

The fabrication of the laminate is done by filament winding (hoop

winding) on a drum mandrel mounted on a modified center lathe. The

green layup obtained is cut into laminae of the desired orientations and

stacked in the predefined way to a required thickness. The stacked

laminate is cured at elevated temperatures under a pressure from a

pressure plate. The edges of the laminate are trimmed first and it is then

cut in to required size.

The specimens are then subjected to indentation test on a

universal testing machine (UTM) for a fixed indenter depth. An

investigative study is conducted into the results obtained from test data.

A number of illustrations are shown regarding the damage in the

specimens of different fiber orientation and with different percentages of

E-glass powder. Also indentation depth, contact radius, spring back

effect, and maximum load carrying capacity are studied.


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CONTENTS PAGE NO:

CHAPTER :1

INTRODUCTION

1.1 Overview of composites. 51.2 Historical Development/Historical Overview. 51.3 What is composite material. 8

1.4 Classification of composites. 121.5 Structure of composites. 241.6 Advantages of composites. 251.7 Applications of composites. 261.8 Examples of composite materials. 271.9 Scope of Project. 29

CHAPTER:2

LITERATURE SURVE 30

CHAPTER:3

MATERIALS AND METHODS 32

3.1 Hardener. 32


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3.2 Epoxy. 32

3.3 Fibres/Reinforcement materials. 34

3.3.1 Types of fibres. 35

3.3.2 Mechanical properties of fibres. 43

3.3.3 Fibre manufacturing. 46

3.3.4 Key properties. 47

3.4 Processing of composites. 49

3.4.1 Curing 52

CHAPTER:4

EXPERIMENTAL PROCEDURE. 56

4.1 0.5 mm/min rate of loading on composite laminates

without E-glass powder. 57


with E-glass powder. 62


with E-glass powder. 71

CHAPTER:5


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5.1 RESULTS AND DISCUSSIONS. 80

5.2 REFERENCES 85


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CHAPTER 1

INTRODUCTION

1.1 Overview of composites

The development of composite materials and related design and

manufacturing technologies is one of the most important advances in the

history of materials. Composites are multifunctional materials having

unprecedented mechanical and physical properties that can be tailored

to meet the requirements of a particular application. Many composites

also exhibit great resistance to high-temperature corrosion and oxidationand wear. These unique characteristics provide the mechanical engineer

with design opportunities not possible with conventional monolithic

(unreinforced) materials. Composites technology also makes possible the

use of an entire class of solid materials, ceramics, in applications for

which monolithic versions are unsuited because of their great strength

scatter and poor resistance to mechanical and thermal shock. Further,

many manufacturing processes for composites are well adapted to the

fabrication of large, complex structures, which allows consolidation of

parts, reducing manufacturing costs.

1.2 Historical Development / Historical overview:

Past: After making and controlling fire and inventing the wheel,

spinning of continuous yarns is probably the most important

development of mankind, enabling him to survive outside the tropical

climate zones and spread across the surface of the Earth. Flexible fabrics

made of locally grown and spun fibres as cotton; flax and jute were a big

step forward compared to animal skins. More and more natural

resources were used, soon resulting in the first composites; straw


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reinforced walls, and bows (Figure M.1.1.a) and chariots made of glued

layers of wood, bone and horn. More durable materials as wood and

metal soon replaced these antique composites.

Fig M.1.1.a Composite Korean bow

Present:

Originating from early agricultural societies and being almost forgotten

after centuries, a true revival started of using lightweight composite

structures for many technical solutions during the second half of the

20th century. After being solely used for their electromagnetic properties

(insulators and radar-domes), using composites to improve the structural

performance of spacecraft and military aircraft became popular in the

last two decades of the previous century. First at any costs, with

development of improved materials with increasing costs, nowadays cost

reduction during manufacturing and operation are the main technology

drivers. Latest development is the use of composites to protect man


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against fire and impact and a tendency to a more environmental friendly

design, leading to the reintroduction of natural fibres in the composite

technology. Increasingly nowadays, the success of composites in

applications, by volume and by numbers, can be ranked by accessibility

and reproducibility of the applied manufacturing techniques. Some

examples of use of natural fibers(M.1.1bM.1.1.e)


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Future:

In future, composites will be manufactured even more according to an

integrated design process resulting in the optimum construction according

to parameters such as shape, mass, strength, stiffness, durability, costs,

etc. Newly developed design tools must be able to instantaneously show

customers the influence of a design change on each one of these

parameters.

1.3 What is Composite Material?

Composite materials are engineering materials made from two or more

constituent materials that remain separate and distinct on a

macroscopic level while forming a single component. There are two

categories of constituent materials: matrix and reinforcement. 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. The primary functions of the matrix are to transfer stressesbetween the reinforcing fibers/particles and to protect them from

mechanical environmental damage whereas the presence of

fibers/particles in a composite improves its mechanical properties such

as strength, stiffness etc. The objective is to take advantage of the

superior properties of both materials without compromising on the

weakness of either. As defined by Agarwal and Broutman composite

means material having two or more distinct constituent materials or

phases. It is only when the constituent phases have significantly different

physical properties and thus the composite properties are noticeably

different from the constituent materials


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Fibers or particles embedded in matrix of another material are the best

example of modern-day composite materials, which are mostly

structural.

Laminates are composite material where different layers of materials

give them the specific character of a composite material having a specific

function to perform. Fabrics have no matrix to fall back on, but in them,

fibers of different compositions combine to give them a specific character.

Reinforcing materials generally withstand maximum load and serve the

desirable properties.

Further, though composite types are often distinguishable from oneanother, no clear determination can be really made. To facilitate

definition, the accent is often shifted to the levels at which differentiation

take place viz., microscopic or macroscopic.

In matrix-based structural composites, the matrix serves two paramount

purposes viz., binding the reinforcement phases in place and deforming

to distribute the stresses among the constituent reinforcement

materials under an applied force.

The demands on matrices are many. They may need to temperature

variations, be conductors or resistors of electricity, have moisture

sensitivity etc. This may offer weight advantages, ease of handling and

other merits which may also become applicable depending on the

purpose for which matrices are chosen.

Solids that accommodate stress to incorporate other constituents provide

strong bonds for the reinforcing phase are potential matrix materials. A

few inorganic materials, polymers and metals have found applications as

matrix materials in the designing of structural composites, with


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commendable success. These materials remain elastic till failure occurs

and show decreased failure strain, when loaded in tension and

compression. Composites cannot be made from constituents with

divergent linear expansion characteristics. The interface is the area of

contact between the reinforcement and the matrix materials. In some

cases, the region is a distinct added phase. Whenever there is

interphase, there has to be two interphases between each side of the

interphase and its adjoint constituent. Some composites provide

interphases when surfaces dissimilar constituents interact with each

other. Choice of fabrication method depends on matrix properties and

the effect of matrix on properties of reinforcements. One of the prime

considerations in the selection and fabrication of composites is that theconstituents should be chemically inert non-reactive.

Properties of Matrix Materials:

Naturally fibers and whiskers are of little use unless they are

bonded together to take form of structural element that can carry loads.


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The binder material is usually called a matrix. The purpose of the

matrix is manifold support of fibers or whiskers, protection of the fibers

or whiskers, stress transfer between broken fibers or whiskers, etc.

Typically the matrix is of considerably lower density, stiffness, and

strength than fibers or whiskers. However the combination of fibers or

whiskers and a matrix can have very high strength and stiffness yet still

have low density. Matrix materials can be polymers, metals, ceramics or

carbon.

Polymers (poly =many and mer = unit or molecule) exist in at least

three major forms i.e linear, branched, or cross linked. A linear polymer

is merely a chain of mers. A branched polymer consists of a primary

chain of mers with other chains that are attached in three dimensions

just like tree branches. Finally, a cross linked polymer has large number

of three dimensional highly interconnected chains. Linear polymers have

the least strength and stiffness, whereas cross linked polymer have most

because of their inherently stiffer and stronger internal structure. The

three main classes of structural polymers are rubbers, thermoplastics,

and thermo sets. Rubbers are cross linked polymers that have semi

crystalline state well below room temperature. Thermoplastics are

polymers that branch, but generally dont cross link very much if at all.

Thus, they usually can be repeatedly softened on heating and hardened

on cooling. Examples of thermoplastics are nylon, polyethylene, and

polysulfone. Thermo sets are polymers that are chemically reacted until

almost all molecules are irreversibly cross linked in a three dimensional

network. Thus, once an epoxy has set, it cannot be changed in form.

Examples of thermo sets include epoxies, phenolics, and polyimides.

Other matrix materials include metals that can be made to flow

around an in-place fiber system by diffusion bonding or by heating

vacuum infiltration. Common examples are shown in fig 1.3.1


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a) linear b)branched c)cross linked d)network

figure 1.3.1

1.4 Classification of Composites

Composite materials are commonly classified at following two distinct

levels:

The first level of classification is usually made with respect to the matrix

constituent. The major composite classes include Organic MatrixComposites (OMCs), Metal Matrix Composites (MMCs) and Ceramic

Matrix Composites (CMCs). The term organic matrix composite is

generally assumed to include two classes of composites, namely Polymer

Matrix Composites (PMCs) and carbon matrix composites commonly

referred to as carbon-carbon composites.

The second level of classification refers to the reinforcement form - fibre

reinforced composites, laminar composites and particulate

composites. Fibre Reinforced composites (FRP) can be further divided

into those containing discontinuous or continuous fibres.


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Fibre Reinforced Composites are composed of fibres embedded in matrix

material. Such a composite is considered to be a discontinuous fibre or

short fibre composite if its properties vary with fibre length. On the other

hand, when the length of the fibre is such that any further increase in

length does not further increase, the elastic modulus of the composite,

the composite is considered to be continuous fibre reinforced. Fibres are

small in diameter and when pushed axially, they bend easily although

they have very good tensile properties. These fibres must be supported to

keep individual fibres from bending and buckling.

Laminar Composites are composed of layers of materials held together by

matrix. Sandwich structures fall under this category.

Particulate Composites are composed of particles distributed or

embedded in a matrix body. The particles may be flakes or in powder

form. Concrete and wood particle boards are examples of this category.

1.4.1 Polymer Matrix Composites (PMC)/Carbon MatrixComposites or Carbon-Carbon Composites

Polymers make ideal materials as they can be processed easily, possess

lightweight, and desirable mechanical properties. It follows, therefore, that

high temperature resins are extensively used in aeronautical applications.

Two main kinds of polymers are thermosets and thermoplastics.

Thermosets have qualities such as a well-bonded three-dimensional

molecular structure after curing. They decompose instead of melting on

hardening. Merely changing the basic composition of the resin is enough to

alter the conditions suitably for curing and determine its other

characteristics. They can be retained in a partially cured condition too over

prolonged periods of time, rendering Thermosets very flexible. Thus, they are


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most suited as matrix bases for advanced conditions fiber reinforced

composites. Thermosets find wide ranging applications in the chopped fiber

composites form particularly when a premixed or moulding compound with

fibers of specific quality and aspect ratio happens to be starting material as

in epoxy, polymer and phenolic polyamide resins.

Thermoplastics have one- or two-dimensional

molecular structure and they tend to at an elevated temperature and show

exaggerated melting point. Another advantage is that the process of

softening at elevated temperatures can reversed to regain its properties

during cooling, facilitating applications of conventional compress

techniques to mould the compounds. Resins reinforced with thermoplastics

now comprised an emerging group of composites.

Figure 1.4.1 a

A small quantum of shrinkage and the tendency of the shape to

retain its original form are also to be accounted for. But reinforcements

can change this condition too. The advantage of thermoplastics systems

over thermosets are that there are no chemical reactions involved, which

often result in the release of gases or heat. Manufacturing is limited by

the time required for heating, shaping and cooling the structures.


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Thermoplastics resins are sold as moulding compounds. Fiber

reinforcement is apt for these resins. Since the fibers are randomly

dispersed, the reinforcement will be almost isotropic. However, when

subjected to moulding processes, they can be aligned directionally.

There are a few options to increase heat resistance in

thermoplastics. Addition of fillers raises the heat resistance. But all

thermoplastic composites tend loose their strength at elevated

temperatures. However, their redeeming qualities like rigidity,

toughness and ability to repudiate creep, place thermoplastics in the

important composite materials bracket. They are used in automotivecontrol panels, electronic products encasement etc.

Newer developments augur the broadening of the scope of

applications of thermoplastics. Huge sheets of reinforced thermoplastics

are now available and they only require sampling and heating to be

moulded into the required shapes. This has facilitated easy fabrication of

bulky components, doing away with the more cumbersome moulding

compounds.

Thermosets are the most popular of the fiber composite matrices

without which, research and development in structural engineering field

could get truncated. Aerospace components, automobile parts, defense

systems etc., use a great deal of this type of fiber composites. Epoxy

matrix materials are used in printed circuit boards and similar areas.


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Figure 1.4.1.b

Direct condensation polymerization followed by rearrangement

reactions to form heterocyclic entities is the method generally used to

produce thermoset resins. Water, a product of the reaction, in both

methods, hinders production of void-free composites. These voids have a

negative effect on properties of the composites in terms of strength and

dielectric properties. Polyesters phenolic and Epoxies are the two

important classes of thermoset resins.

Epoxy resins are widely used in filament-wound composites andare suitable for moulding prepress. They are reasonably stable to

chemical attacks and are excellent adherents having slow shrinkage

during curing and no emission of volatile gases. These advantages,

however, make the use of epoxies rather expensive. Also, they cannot be

expected beyond a temperature of 140C. Their use in high technology

areas where service temperatures are higher, as a result, is ruled out.

Polyester resins on the other hand are quite easily accessible,

cheap and find use in a wide range of fields. Liquid polyesters are

stored at room temperature for months, sometimes for years and the

mere addition of a catalyst can cure the matrix material within a short

time. They are used in automobile and structural applications.


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The cured polyester is usually rigid or flexible as the case may be

and transparent. Polyesters withstand the variations of environment and

stable against chemicals. Depending on the formulation of the resin or

service requirement of application, they can be used up to about 75C or

higher. Other advantages of polyesters include easycompatibility with

few glass fibers and can be used with verify of reinforced plastic

accoutrey.

Aromatic Polyamides are the most sought after candidates as the

matrices of advanced fiber composites for structural applications

demanding long duration exposure for continuous service at around 200-250C .

1.4.2 According to geometry:

Most composite materials developed thus far have been fabricated to

improve mechanical properties such as strength, stiffness, toughness,

and high temperature performance. It is natural to study together the

composites that have a common strengthening mechanism. The

strengthening mechanism strongly depends on the geometry of the

reinforcement. Therefore, it is quite convenient to classify composite

materials on the basis of the geometry of a representative unit of

reinforcement.

1.4.2.a Fibrous composite

A fiber is characterized by its length being much greater compared

to its cross-sectional dimensions. The dimensions of the reinforcement

determine its capability of contributing its properties to the composite.


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Fibers are very effective in improving the fracture resistance of the matrix

since a reinforcement having a long dimension discourages the growth of

incipient cracks normal to the reinforcement that might otherwise lead to

failure, particularly with brittle matrices. Man-made filaments or fibers of

non polymeric materials exhibit much higher strength along their length

since large flaws, which may be present in the bulk material, are

minimized because of the small cross-sectional dimensions of the fiber.

In the case of polymeric materials, orientation of the molecular structure

is responsible for high strength and stiffness.Fibrous composites can be

broadly classified as single layer and multi layer composites on the basis

of studying both the theoretical and experimental properties. Single layer

compositesmay actually be made from several distinct layers with eachlayer having the same orientation and properties and thus the entire

laminate may be considered a single layer composite. Most composites

used in structural applications are multilayered; that is, they consist of

several layers of fibrous composites. Each layer or lamina is a single

layer composite and its orientation is varied according to design. Several

identical or different layers are bonded together to form a multilayered

composites usable for engineering applications. When the constituent

materials in each layer are the same, they are called simply laminates.

Hybrid laminates refer to multilayered composites consisting of layers

made up of different constituent materials. Reinforcing fibers in a single

layer composite may be short or long compared to its overall dimensions.

Composites with long fibers are called continuous fiber reinforced

composites and those with short fibers, discontinuous fiber reinforced

composites. The continuous fibers in single layer composites may be all

aligned in one direction to form a unidirectional composite. Such

composites are fabricated by laying the fibers parallel and saturating

them with resinous material. The bidirectional reinforcement may be

provided in a single layer in mutually perpendicular directions as in a


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woven fabric. The bidirectional reinforcement may be such that the

strengths in two perpendicular directions are approximately equal. The

orientation of discontinuous fibers cannot be easily controlled in a

composite material.

So fibers can be either randomly oriented or preferred oriented. In most

cases the fibers areassumed to be randomly oriented in the composites.

However, in the injection molding of a fiber reinforced polymer,

considerable orientation can occur in the flow direction and which acase

of preferred oriented fibers in the composites.

1.4.2.b Particulate Composites

As the name itself indicates, the reinforcement is of particle nature

(platelets are also included in this class). It may be spherical, cubic,

tetragonal, a platelet, or of other regular or irregular shape, but it is

approximately equiaxed. In general, particles are not very effective in

improving fracture resistance but they enhance the stiffness of the

composite to a limited extent. Particle fillers are widely used to improve

the properties of matrix materials such as to modify the thermal and

electrical conductivities, improve performance at elevated temperatures,

reduce friction, increase wear and abrasion resistance, improve

machinability, increase surface hardness and reduce shrinkage. Also, in

case of particulate reinforced composites the particle can be either

randomly oriented or preferred oriented.


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1.4.3 According to type of matrix material they are

classified as:

Metal Matrix Composites (MMC)

Ceramic Matrix Composites (CMC)

Polymer Matrix Composites (PMC)

1.4.3.a Metal Matrix Composites

Metal Matrix Composites have many advantages over monolithic metals

like higher specific modulus, higher specific strength, better properties at

elevated temperatures, and lower coefficient of thermal expansion.

Because of these attributes metal matrix composites are under

consideration for wide range of applications viz. combustion chamber

nozzle (in rocket, space shuttle), housings, tubing, cables, heat

exchangers, structural members etc

1.4.3.b Ceramic matrix Composites

One of the main objectives in producing ceramic matrix composites is to

increase the toughness Naturally it is hoped and indeed often found that

there is a concomitant improvement in strength and stiffness of ceramic

matrix composites.

1.4.3.c Polymer Matrix Composites

Most commonly used matrix materials are polymeric. The reasons for

this are twofold. In general the mechanical properties of polymers are

inadequate for many structural purposes. In particular their strength

and stiffness are low compared to metals and ceramics. These difficulties

are overcome by reinforcing other materials with polymers. Secondly the

processing of polymer matrix composites need not involve high pressure


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and doesnt require high temperature. Also equipments required for

manufacturing polymer matrix composites are simpler. For this reason

polymer matrix composites developed rapidly and soon became popular

for structural applications. Composites are used because overall

properties of the composites are superior to those of the individual

components for example polymer/ceramic. Composites have a greater

modulus than the polymer component but arent as brittle as ceramics.

1.4.4 Classification Based on Reinforcements

Introduction to Reinforcements

Reinforcements for the composites can be fibers, fabrics particles or

whiskers. Fibers are essentially characterized by one very long axis with

other two axes either often circular or near circular. Particles have no

preferred orientation and so does their shape. Whiskers have a preferred

shape but are small both in diameter and length as compared to fibers.

Figure 1.4.4


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Two types of polymer composites are:

Fiber reinforced polymer (FRP)

Particle reinforced polymer (PRP)

1.4.4.a Fiber Reinforced Polymer

Common fiber reinforced composites are composed of fibers and a

matrix. Fibers are the reinforcement and the main source of strength

while matrix glues all the fibers together in shape and transfers stresses

between the reinforcing fibers. The fibers carry the loads along their

longitudinal directions. Sometimes, filler might be added to smooth the

manufacturing process, impact special properties to the composites, and

/or reduce the product cost. Common fiber reinforcing agents include

asbestos, carbon /graphite fibers, beryllium, beryllium carbide, beryllium

oxide, molybdenum, aluminium oxide, glass fibers, polyamide,natural

fibers etc. Similarly common matrix materials include epoxy, phenolic,

polyester, polyurethane, peek, vinyl ester etc. Among these resin

materials, epoxy is widely used for its higher adhesion and less

shrinkage property.

1.4.4.b Particle Reinforced Polymer

Particles used for reinforcing include ceramics and glasses such as small

mineral particles, metal particles such as aluminium and amorphous

materials, including polymers and carbon black.

Particles are used to increase the modules of the matrix

and to decrease the ductility of the matrix. Particles are also used to

reduce the cost of the composites. Reinforcements and matrices can be

common, inexpensive materials and are easily processed.


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Some of the useful properties of ceramics and glasses include high

melting temperature, low density, high strength, stiffness, wear

resistance, and corrosion resistance. Many ceramics are good electrical

and thermal insulators. Some ceramics have special properties; some

ceramics are magnetic materials; some are piezoelectric materials; and a

few special ceramics are even superconductors at very low temperatures.

Ceramics and glasses have one major drawback: they are brittle. An

example of particle reinforced composites is an automobile tire, which

has carbon black particles in a matrix of poly-isobutylene elastomeric

polymer

1.5 Structure of Composite

Structure of composite material A fiber is characterized by its length

being much greater compared to its cross-sectional dimensions. The

dimensions of the reinforcement determine its capability of contributing

its properties to the composite.

Fibers are very effective in improving the fracture resistance of the matrix

since a reinforcement having a long dimension material, are minimized

because of the small cross-sectional dimensions of the fiber. In the case

of polymeric materials, orientation of the molecular structure is

responsible for high strength and stiffness.

Fibrous composites can be broadly classified as single layer and multi

layer composites on the basis of studying both the theoretical and

experimental properties. Single layer composites may actually be made

from several distinct layers with each layer having the same orientation

and properties and thus the entire laminate may be considered a single

layer composite


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Properties

1) Nature of the constituent material (bonding strength)

2) The geometry of the reinforcement (shape, size)

3) The concentration distribution(vol. fraction of reinforcement)

4) The orientation of the reinforcement(random or preferred)

Good adhesion (bonding) between matrix phase and displaced

phase provides transfer of load applied to the material to the displaced

phase via the interface. Good adhesion is required for achieving high

level of mechanical properties of composites. Very small particles less

than 0.25 micrometer finely distributed in the matrix impede movement

of dislocations and deformation of the material. They have strengthening

effect. Large dispersed phase particles have low share load applied to the

material resulting in increase of stiffness and decrease of ductility.

Orientation of reinforcement: Planar:-In the form of 2-D woven fabric.

When the fibers are laid parallel, the composite exhibits axistrope.

Random or Three Dimensional:-The composite material tends to posses

isotropic properties.

One Dimensional: - Maximum strength and stiffness are obtained in thedirection of fiber.

1.6 Advantages of Composites

Advantages of composites over their conventional counterparts are the

ability to meet diverse design requirements with significant weight

savings as well as strength-to-weight ratio. Some advantages of

composite materials over conventional ones are as follows:

Tensile strength of composites is four to six times greater than that ofsteel or aluminium (depending on the reinforcements).


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Industry Examples Comments

Aircraft Door, elevators 20-35% Weight savings

Aerospace Space Shuttle, Space stations Great weight savings

Automotive Body frames, engine

components

High stiffness & damage

toleranceChemical Pipes, Tanks, Pressure vessels Corrosion resistance

Construction Structural & decorative panels,

Fuel tanks etc.

Weight savings, portable.

Improved torsional stiffness and impact properties.Higher fatigue endurance limit (up to 60% of ultimate tensile strength).

30% - 40% lighter for example any particular aluminium structuresdesigned to the same functional requirements.

Lower embedded energy compared to other structural metallic materialslike steel, aluminium etc.

Composites are less noisy while in operation and provide lower vibrationtransmission than metals.

Composites are more versatile than metals and can be tailored to meetperformance needs and complex design requirements.

Long life offer excellent fatigue, impact, environmental resistance andreduce maintenance.

Composites enjoy reduced life cycle cost compared to metals. Composites exhibit excellent corrosion resistance and fire retardancy. Improved appearance with smooth surfaces and readily incorporable

integral decorative melamine are other characteristics of composites.

Composite parts can eliminate joints / fasteners, providing partsimplification and integrated design compared to conventional metallic

parts.

1.7 Applications of Composites

Figure 1.7


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1.8 EXAMPLES OF COMPOSITE MATERIALS

Fibre reinforced plastics:

Classified by type of fiber:

Wood (cellulose fibers in a lignin and hemicellulose matrix)

Carbon-fibre reinforced plastic (CRP)

Glass-fibre reinforced plastic (GRP) (informally, "fiberglass")

Classified by matrix:

Thermoplastic Composites

Short fiber thermoplastics

Long fiber thermoplastics or long fiber reinforced thermoplastics

Glass mat thermoplastics

Continuous fiber reinforced thermoplastics

Thermoset Composites

Reinforced carbon-carbon (carbon fibre in a graphite matrix)


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Metal matrix composites (MMCs):

White cast iron

Hardmetal (carbide in metal matrix)

Metal-intermetallic laminate

Ceramic matrix composites:

Bone (hydroxyapatite reinforced with collagen fibers)

Cermet (ceramic and metal)

Concrete

Organic matrix/ceramic aggregate composites

Asphalt concrete

Dental composite

Syntactic foam

Mother of Pearl

Chobham armour (see composite armour)

Engineered wood


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Plywood

Oriented strand board

Wood plastic composite (recycled wood fiber in polyethylene matrix)

Pykrete (sawdust in ice matrix)

Plastic-impregnated or laminated paper or textiles

Arborite

Formica (plastic)

1.9 Scope of the project

The basic aim of the present work is to develop and characterize a

new class of composites with epoxy as polymer matrix and glass fiber as

the reinforcing material. Their physical and mechanical characterization

is done. Attempt is made to use TiO2 as filler in these fiber reinforced

.polymer matrix composites. Characterization of the resulting TiO2 filled

glass fiber reinforced epoxy composite is done. The experimentally

measured database of composites has also been predicted. This work is

expected to introduce a new class of functional polymer composites

suitable for tribological applications.


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CHAPTER 2

LITERATURE SURVEY

This chapter outlines some of the recent reports published in

literature on composites of fiber reinforced polymer composites. Polymer

composite materials have generated wide interest in various engineering

fields, particularly in aerospace applications. Research is underway

worldwide to develop newer composites with varied combinations of

fibers and fillers so as to make them useable under different operational

conditions. The improved performance of polymer composites in

engineering applications by the addition of filler materials has shown a

great promise and so has become a subject of considerable interest.

Ceramic filled polymer composites have been the subject of extensive

research in last two decades. Various kinds of polymers and polymer

matrix composites reinforced with ceramic particles have a wide range of

industrial applications such as heaters, electrodes, composites with

thermal durability at high temperature etc.

These engineering composites are desired due to their low density,

high corrosion resistance consisting of ceramic or metal particles and

fiber fillers made of glass are being used these days to dramatically

improve the wear resistance even up to three orders of magnitude. The

inclusion of inorganic fillers into polymers for commercial applications is

primarily aimed at the cost reduction and stiffness improvement. Along

with fiber-reinforced composites, the composites made with particulate

fillers have been found to perform well in many real operational

conditions. It is reported by Bonner that with the inclusion of micro-sized

particulates into polymers, a high filler content (typically greater than 20

vol. %) is generally required to bring the above stated positive effects into


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play. But at the same time, this may also have detrimental effects on

some important properties of the matrix polymers such as processability,

appearance, density and aging performance. It has also been reported

that the fracture surface energies of epoxy and polyester resin and their

resistance to crack propagation are relatively low.

But if particulate filler is added to these resins, the

particles inhibit crack growth. As the volume fraction of filler is varied,

the fracture energy increases up to a critical volume fraction and then

decreases again. Srivastava showed that the fracture toughness of epoxy

resin could be improved by addition of flyash particles as filler. The fillersalso affect the tensile properties according to their packing

characteristics, size and interfacial bonding. The maximum volumetric

packing fraction of filler reflects the size distribution and shapes of the

particles. Recently, it has been observed that by incorporating filler

particles into the matrix of fibre reinforced composites, synergistic effects

may be achieved in the form of higher modulus and reduced material

costs, yet accompanied with decreased strength and impact toughness.

Polymer composites with both discontinuous and continuous fibre

reinforcement possess usually very high specific (i.e. density related)

stiffness and strength when measured in plane. Therefore, such

composites are frequently used in engineering parts in automobile,

aerospace, marine and energetic applications.


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HAPTER 3

TERIALS AND METHODS

s chapter describes the details of processing of the composites and the experimental

cedures followed for their characterization and tribological evaluation. The raw materials

d in this work are

1. E-glass fiber

2. E-Glass powder

3. Epoxy resin

Hardener:

The hardener used in Epoxy is polyamine. A polyamine is an organic compound

ing two or more primary amino groups -NH2.This class of compounds includes several

thetic substances that are important feed stocks for the chemical industry, such as

ylene diamine H2N-CH2-CH2-NH2, 1,3-diaminopropane H2N-(CH2)3-NH2, and hex

hylenediamine H2N-(CH2)6-NH2.

The amine groups react with the epoxide groups to form a covalent bond. Each NH

up can react with an epoxide group, so that the resulting polymer is heavily cross

ed, and is thus rigid and strong.

Epoxy:

Epoxyis a copolymer; that is, it is formed from two different chemicals. These are

rred to as the "resin" and the "hardener.

When these compounds are mixed together, the amine groups react with the

xide groups to form a covalent bond. Each NH group can react with an epoxide group,

hat the resulting polymer is heavily cross linked, and is thus rigid and strong.


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The process of polymerization is called "curing", and can be controlled through

perature, choice of resin and hardener compounds, and the ratio of said compounds;

process can take minutes to hours. Some formulations benefit from heating during the

e period, whereas others simply require time, and ambient temperatures.

The applications for epoxy-based materials are extensive and include coatings,

esives and composite materials such as those using carbon fiber and fiberglass

forcements.

sin:

Resin is a natural or synthetic compound which begins in a highly viscous state and

dens with treatment. Typically, resin is soluble in alcohol, but not in water. There are a

mber of different classes of resin, depending on exact chemical composition and

ential uses.

Matrix resins bind glass-reinforcing fibers together, protecting them from impact and

environment. Glass fiber properties such as

strength dominate in continuously reinforced composites. When glass is used as a

continuous reinforcement, resin properties dominate and are enhanced by the glass.

Polymer matrix resins fall into two categories: thermo set and thermoplastic. The

erence is in their chemistry. Thermo set resin is chemically comprised of molecular

ins that crosslink during the cure reaction (set off by heat, catalyst, or both) and "set"

a final rigid form. Molecular chains in thermoplastic resin are processed at higher

peratures and remain "plastic," or capable of being reheated and reshaped. While the

deoffs between thermosets and thermoplastics have been debated extensively, engineers

find that material suppliers will tailor matrix resin formulations best for their

lication


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Fibres/Reinforcement materials:

Organic and inorganic fibers are used to reinforce composite materials. Almost all

anic fibers have low density, flexibility, and elasticity. Inorganic fibers are of high

dulus, high thermal stability and possess greater rigidity than organic fibers and not

hstanding the diverse advantages of organic fibers which render the composites in which

y are used.

Mainly, the following different types of fibers namely, glass fibers, silicon carbide

rs, high silica and quartz fibers, alumina fibers, metal fibers and wires, graphite fibers,

on fibers, aramid fibers and multi phase fibers are used. Among the glass fibers, it is

in classified into E-glass, S-glass, A- glass, R-glass etc.

There is a greater market and higher degree of commercial movement of organic

rs.

The potential of fibers of graphite, silicon carbide and boron are also exercising the

ntific mind due to their applications in advanced composites.

.1Types of fibers

1.a Glass Fibers

Over 95% of the fibers used in reinforced plastics are glass fibers, as they are

xpensive, easy to manufacture and possess high strength and stiffness with respect to

plastics with which they are reinforced.


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Their low density, resistance to chemicals, insulation capacity are other bonus

racteristics, although the one major disadvantage in glass is that it is prone to break

n subjected to high tensile stress for a long time..

However, it remains break-resistant at higher stress-levels in shorter time frames.

s property mitigates the effective strength of glass especially when glass is expected to

tain such loads for many months or years continuously.

Period of loading, temperature, moisture and other factors also dictate the tolerance

ls of glass fibers and the disadvantage is further compounded by the fact that the

tleness of glass does not make room for prior warning before the catastrophic failure.

But all this can be easily overlooked in view of the fact that the wide range of glassr variety lend themselves amicably to fabrication processes like matched die moulding,

ment winding lay-up and so on. Glass fibers are available in the form of mats, tapes,

h, continuous and chopped filaments, rovings and yarns.

Addition of chemicals to silica sand while making glass yields different types of

ses.

1.b Metal Fibers

As reinforcements, metal fibers have many advantages. They are easily produced

ng several fabrication processes and are more ductile, apart from being not too sensitive

urface damage and possess high strengths and temperature resistance.

However, their weight and the tendency to react with each other through alloying

chanisms are major disadvantages.Steel wire is the most extensively used reinforcement in most large-scale metal

ment applications. Wire is used for its capacity to enhance the tensile strength of

crete and continuous metal fibers are the reinforcing constituents in metal and ceramic

mposite materials.


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1.c Ceramic fibers improve vastly in performance when a fine metal outline is

orporated with refractory ceramics by improving their thermal shock and impact

stance properties.

1.d Metal wires, of the continuous version, also reinforce plastics like polyethylene and

xy. Such combinations ensure high strength, light weight and good fatigue resistance.

Besides, continuous metal fibers are easily handled, unlike glass fibers. Better

ural properties are observed in some metal fibers reinforced plastic composites which

offer improved strength and weight, than glass fibers.

wever, their poor tolerance of high temperatures and the resultant steep variation of

rmal expansion coefficient with the resins are a discouragement that limits their

lication.

1.d Alumina Fibers

Alumina or aluminum oxide fibers, basically developed for use in metal matrices are

sidered a potential resin-matrix composite reinforcement. It offers good compressive

ngth rather than tensile strength. It is important property is it is high melting point of

ut 2000C and the composite can be successfully used at temperatures up to about 1000C.

gnesium and aluminum matrices frequently use alumina fiber reinforced composites as they

not damage the fiber even in the liquid state.

1.e Boron Fibers

They are basically composites, in which boron is coated on a substance which forms the

strate, usually made of tungsten.

Boron-tungsten fibers are obtained by allowing hot tungsten filament through a mixture

gases. Boron is deposited on tungsten and the process is continued until the desired

kness is achieved. The tungsten however remains constant in its thickness.

Properties of boron fibers generally change with the diameter, because of the changing

o of boron to tungsten and the surface defects that change according to size. However, they


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known for their remarkable stiffness

33and strength. Their strengths often compare with those of glass fibers, but their tensile

dulus is high, almost four to five times that of glass. Boron coated carbons are muchaper to make than boron tungsten fiber. But its low modulus of elasticity often works

nst it.

.1.f Silicon Carbide Fibers

Silicon carbide can be coated over a few metals and their room temperature tensile

ngths and tensile moduli are like those of boron-tungsten. The advantages of silicon

bide-tungsten are several and they are more desirable than uncoated boron tungstenrs. Elevated temperature performance and the fact that they reported only a 35% loss of

ngth at 1350C are their best qualities. Silicon carbide-tungsten and silicon carbide-

bon have both been seen to have very high stress-rupture strength at 1100C and

0C. Uncoated boron-tungsten fibers tend to lose all their strength at temperatures over

C. Silicon carbide fibers do not react with molten aluminium, unlike uncoated boron

they also withstand high temperatures used in hot-press titanium matrices.

However, silicon carbide-tungsten fibers are dense compared to boron- tungsten

rs of the same diameter. They are prone to surface damage and need careful, delicate

dling, especially during fabrication of the composite. Further, above 930C, weakening

ctions occur between tungsten and silicon carbide, making it difficult to maintain

ance in high-temperature matrix formations.

Silicon carbide on 'carbon substrates have several advantages, viz. no, reaction at

h temperature, being lighter than silicon carbide tungsten and possessing tensile

ngths and modulus that is are often better than those of silicon carbide-tungsten and

on fibers.

.1.g Aramid Fibers


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Aramid fibers are made from aromatic polyamides which are long polymeric .chains

aromatic rings. They are structures in which six carbon atoms are bonded to each

er and to combinations of hydrogen atoms. In aramid fibers, these rings occur and

ccur to form the fibers. They were initially used to reinforce automobile tires. Since then,

y have also found other uses like bullet proof vests. As high strength applications, their

in power boats is not uncommon.

Aramid have high tensile strength, high modulus and low weight. Impact- resistant

uctures can be produced from aramid. The density of aramid fibers is less than that of

s and graphite fibers. They are fire resistant apart from being high-temperature

stant and also unaffected by organic solvents and fuels. But their resistance in acid and

aline media is poor. They are supple and allow themselves to be woven into matrices by

ple processes. Aramid fibers have a negative coefficient of thermal expansion in the fiber

ction and the failure of aramid fibers is unique. When they fail, the fibers break into

all fibrils, which are like fibers within the fibers. This unique failure mechanism is

ponsible for high strength.

.1.h Quartz and Silica Fibers

The glass-types typically contain about 50 to 78% silica. Silica glass is a purer glass

r that can be made by treating fiberglass in an acid bath, which removes all impurities

hout affecting the silica. The final product contains 93 to 99% silica. Quartz is even

re pure, and quartz fibers are made from natural quartz crystals that contain 99.9%

a, possessing nearly all the properties of pure solid quartz.

Ordinary fiberglass, high silica and quartz fibers share several characteristics and

be produced in a range of fiber diameters. Roving or yarns and other forms of fibers

be made from high silica as well as quartz. All matrix materials that accept fiberglass

amenable to high silica and quartz too.

They differ from glass in many factors, however, especially in heat-related properties.


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Although quartz crystals are commonly available, pure crystals are hard to come by.

the other hand, high silica comes from the same material as glass fibers and is easily

essible. However, quartz makes up for its rarity with its capacity to" withstand high

peratures, which silica is incapable of.

Barring this difference, silica and quartz are similar in other respects. They are highly

tic and can be stretched to 1 % of their length before break point. Both silica and

rtz are not affected by acid attacks and are resistant to moisture.

Owing to their thermal properties, silica and quartz are the natural choice as fibers in

eral applications. They have good insulating properties and do not melt at temperatures

to 1600C.In addition, they have low thermal expansion coefficients which make them

hstand high temperatures.

.1.i Graphite Fibers

While use of the term carbon for graphite is permissible, there is one basic difference

ween the two. Elemental analysis of poly-acrylo-nitrile (PAN) base carbon fibers show that

y consist of 91 to 94% carbon. But graphite fibers are over 99% carbon. The difference

es from the fact that the fibers are made at different temperatures.

PAN-based carbon cloth or fiber is produced at about 1320C, while graphite fibers and

h are graphitized at 1950 to 3000C.

The properties of graphite remain unchanged even at very high temperatures, but its

ngness to react readily with most metals at the fabrication stage or during use at very high

peratures is often a stumbling block, as seen in aluminium matrices when carbides are

duced at the interface. These carbides react with moisture with disastrous effects on the

posite material.


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Graphite fibers are some of the stiffest fibers known. The stiffness of the fiber is as high

he graphite content. But a major drawback is that stiffness and strength are inversely

portional to each other.

Forbidding costs make the use of graphite fibers prohibitive. The best glass fibers are far

expensive than the cheapest, lowest quality of graphite, and in PAN-base fibers, other rawerials too are equally expensive. The carbonization and graphitization are time-consuming,

rt from demanding excessive energy, materials and close controls throughout the process.

aper pitch base fibers are now being developed, with greater performance potential and

e are possibilities of the increased use of graphite fibers.

.1.j Multiphase Fibers

Spoolable filaments made by chemical vapour deposition processes are usually the multi

se variety and they usually comprise materials like boron, silicon and their carbides formed

surface of a very fine filament substrate like carbon or tungsten. They are usually good for

h temperature applications, due to their reduced reaction with higher melting temperature

metals than graphite and other metallic fibers. Boron filaments are sought after for

ctural and intermediate-temperature composites.

A poly-phase fiber is a core-sheath fiber consisting of a poly-

talline core.

.1.k E-Glass fiber:

E-Glass or electrical grade glass was originally developed for

ndoff insulators for electrical wiring. It was later found to have excellent fibre forming

abilities and is now used almost exclusively as the reinforcing phase in the material

mmonly known as fiber glass.


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.

Figure 3.3.1.k E-Glass fiber

.2 Mechanical Properties of fibers

Composite materials are not homogeneous. Their properties are dependent on many

ors, the most important of which are the type of fibre, quantity of fibre (as volume

tion) and the configuration of the reinforcement. They are generally completely elastic

to failure and exhibit neither a yield point nor a region of plasticity. They tend to have

strain to failure(less than 3%). The resulting area under the stress/strain curve, which

resents the work done to failure, is relatively small when compared to many metals.

The properties of composites are dependent on the properties of the fibre and therix, the proportion of each and the configuration of the fibres. If all the fibres are

ned in one direction then the composite relatively stiff and strong in that direction, but

he transverse direction it has low modulus and low strength. When a unidirectional

mposite is tested at a small angle from the fibre axis, there is a considerable reduction in

ngth. A similar but less significant effect occurs with the tensile modulus, as shown in

ure 3.3.2


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ME Page 42

Figure 3.3.2

Theoretical variation in tensile modulus with the angle of load relative to the principal

e direction (unidirectional carbon fibre reinforced plastic (UD CFRP), fibre volume fraction

5)

ength and stiffness

Glass fibre reinforced polymer (GFRP)

E glass fibres, which have a modulus of about 70GPa, produce composites with

dest moduli. In the case of unidirectional fibres and the highest typical fibre volume

tion of 0.65, a composite has a modulus of about45GPa and strength of around

0MPa. At right angles to this, in the transverse direction, the modulus approaches that

he resin itself at about4GPa and the strength would be 50100MPa. The unidirectional

mpo-sites used in the ROBUST Project, manufactured using the vacuum process with

preg material in an epoxy matrix, had the following properties:

ongitudinal tensile modulus: 36GPa

ongitudinal tensile strength: 750MPa

longation at break: 3.1%.


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Bidirectional E glass laminates have a typical fibre volume fraction of about 0.4 and a

sile modulus at that volume fraction of about 14GPa.Random laminates (e.g. chopped

nd mat) have a typical fibre volume fraction of about 0.2 and a tensile modulus at that

ume fraction of about9GPa. The use of S2 or R glass improves the composite modulus to

ut60GPa for unidirectional and 20GPa for woven fabric (bidirectional) constructions.

s is at some monetary disadvantage. They are both more expensive than E glass and

y are only available in a fairly limited range of material types and resin compatibilities.

bably the most important virtue of S2 and R glass is their high strength, which is

siderably higher than E glass.

bon and graphite fibers

bon fibre reinforced plastic (CFRP)

The dominant carbon fibres in current use (typically Toray T700) have a tensile

dulus of about 230GPa, a tensile strength of around 5000MPaand a strain-to-failure of

Unidirectional composites produced from them in either an epoxy or vinyl-ester matrix

e the following typical properties:

Longitudinal tensile modulus: 155165GPa

Longitudinal tensile strength: 25003000MPa

Elongation at break: 1.21.3%

Carbon fibres are available which will give a tensile modulus of about250GPa in a

directional composite, comparing very favourably with steel at about 210GPa. However,

this composite is unidirectional, it has extremely low modulus in the transverse

ction. The principal attributes of carbon fibre composites are their very high specific

ness (the ratio of modulus/density), excellent fatigue and environmental resistance.

Currently there are various pultruded CFRP plates available commercially for plate

ding applications. The pultruded plates used in the ROBUST Project, as well as the

es manufactured with prepreg materials, possessed a modulus of about 130GPa and a


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ngth of 1500MPa.Pultruded plates now available from other sources typically exploit

rs with superior properties such as Toray T700, resulting in composites with the

perties shown above. A financial penalty has to be paid for materials exhibiting

perties significantly in excess of these; the strain-to-failure of composites made with

m will also be reduced significantly.

Carbon and graphite have substantial capability as reinforcing fibers, with great

ibility in the properties that can be provided. Primary characteristics for reinforcing

rs in polymer matrix composites are high stiffness and strength. The fibers must

ntain these characteristics in hostile environments such as elevated temperatures,

osure to common solvents and fluids, and environmental moisture. To be used as part

a primary structure material it should also be available as continuous fiber. Theseracteristics and requirements have substantial implications for the physical, chemical

mechanical properties of the fiber, which in turn implies processing and acceptance

ameters.

Interest in carbon fibers for structural materials was initiated in the late 1950s when

thesized rayons in textile form were carbonized to produce carbon fibers for high

perature missile applications. One of the first distinctions to be made is the difference

ween carbon and graphite fibers, although the terms are frequently used

rchangeably.

Background information for these differences is contained in the following sections.

primary purpose of making this distinction here is to alert the reader that users may

an different things when referring to graphite versus carbon fibers.

Carbon and graphite fibers are both based on graphene (hexagonal) layer networks

sent in carbon. If the graphene layers or planes stack with three dimensional orders the

erial is defined as graphite. Usually extended time and temperature processing is

uired to form this order, making graphite fibers more expensive. Because the bonding

ween planes is weak, disorder frequently occurs such that only the two dimensional


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ME Page 45

ering within the layers is present. This material is defined as carbon. With this

inction made, it should be understood that while some differences are implied, there is

a single condition which strictly separates carbon from graphite fibers, and even

phite fibers retain some disorder in their structure.

.3 Fiber Manufacture:

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

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

s to flow. Continuous fibers can be drawn out through the holes and wound onto

ndles, while short fibers may be produced by spinning the crown, which forces molten

s out through the holes centrifugally. Fibers are cut to length using mechanical means

air jets. Fiber dimension and to some extent properties can be controlled by the process

ables such as melt temperature (hence viscosity) and drawing/spinning rate. The

perature window that can be used to produce a melt of suitable viscosity is quite large,

king this composition suitable for fiber forming.

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

nts. These reduce the effects of fiber- fiber abrasion which can significantly degrade the

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

ting and adherence of the matrix material to the fiber

.

mposition

E-Glass is a low alkali glass with a typical nominal composition of SiO2 54wt%, Al2O3

wt%, CaO+MgThe advantageous properties of E-glass generally outweigh the

advantages which include:

Low modulus

Self abrasiveness if not treated appropriately leading to reduced strength Relatively low fatigue resistance


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Higher density compared to carbon fibres and organic fibresO 22wt%, B2O3 10wt%and Na2O+K2O less then 2wt%. Some other materials may also be present at impurity

levels.

.4 Key Properties:

Properties that have made E-glass so popular in 46iberglass and other glass

forced composite include:

Low cost High production rates High strength 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

Processing of the Composites

brication of the Laminate

E-glass/Epoxy composite laminates were prepared by passing the E-glass fibers of

0 TEX, through the resin bath of Epoxy and hardener maintaining a constant

perature of about 45 C.The fibers are then wound on a rotating drum with 15 rpm. After

mplete winding on the drum then it is cut opened and lay on a flat table in the

ospheric condition for about 48 hours to get the


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ME Page 47

kiness. The layers are cut in such a way that the desired fiber direction is obtained. In

experimentation it is decided to prepare the laminates such that the angle between the

rs are15o 30o 45o 60o and 90oas shown in fig-1. The sequence of layup shown in the fig

The number of layup depends on the thickness of the laminate required; here it is

d 20 layers to obtain the thickness of the laminate about 4mm. All the overlapped layers

n compacted between the two parallel flat steel plates with stainless steel spacers of

uired laminate thickness.

The major purpose of lamination is to tailor the directional dependence of strength

stiffness of a composite material to match the loading environment of the structural

ment laminates are uniquely suited to this objective because the principal material

ctions of each layer can be oriented according to need. The plates are clamped with nuts

bolts with washers; the clamped setup is then placed in the oven. Maintain the oven

perature of 800 C for 4 hours and 1200 C for next 4 hours so that any entrapped air or

tile gases will be escaped for the first four hours and chemical reaction between the

xy and hardener will takes place for the next four hours and will lead to permanent set

finally result into a single solid composite laminate. After total curing of 8 hours oven is

n switched off so the temperature in the oven may come down to normal temperature.

e out the composite laminate and trim the edges so that the laminate is ready for testing

pose.

inding parameters

1.Tension of fibre =1.3 kgs2. Resin temperature= 45 0c3. RPM of lathe = 15


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4. Gap between doctor blade and drum = 1.25 mmThe parameters arekept constant for two different windings

LAMENT WINDING SETUP RESIN BATH

DRUM WINDING REMOVING LAYUP


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YUP PLACED ON TABLE APPLYING WAXPOL ON PLATES

LAYING UP LAYERS REMOVING AIR GAP

OMPACTING LAYERS PLACING IN THE OVEN

.2 CURING PROCESS :


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Epoxy is a copolymer; that is, it is formed from two different chemicals. These are referred to

he "resin" and the "hardener". The resin consists of monomers or short chain polymers with an

xide group at either end. Most common epoxy resins are produced from a reaction between

hlorohydrin and bisphenol-A, though the latter may be replaced by similar chemicals. The

dener consists of polyamine monomers, for example Triethylenetetramine (TETA). When thesepounds are mixed together, the amine groups react with the epoxide groups to form a covalent

d.

Each NH group can react with an epoxide group, so that the resulting polymer is

vily crosslinked, and is thus rigid and strong.The process of polymerization is called

ring", and can be controlled through temperature, choice of resin and hardener

mpounds, and the ratio of said compounds; the process can take minutes to hours. Some

mulations benefit from heating during the cure period, whereas others simply requiree, and ambient temperatures. So the laminate that is fabricated is put into a Oven . The

peratures are maintained in two cycles. In the first cycle we have to maintain constant

perature of 80C for 4hours and in the next cycle maintain a temperature of 160C

next 4 hours.

AFTER CURING MARKING

TRIMMING AFTER TRIMMING


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DRILLING AFTER DRILLING

gure 3.6.a specifications of UTM (at CIPET)


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M SPECIFICATIONS


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MPOSITE LAMINATE UNDER TESTING

Experimental procedure

Quasi-static Indentation tests were performed on INSTRON testing machine. The


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mposite laminate of size 150mm x 150mm is placed on a steel supporting frame, with aare opening of size 50mm x 50mm. A similar square opening flat plate is placed ontophe composite laminate; it is then clamped rigidly with nuts and bolts of 6mm size aswn in fig-3. The clamped setup is placed on the loading frame of testing machine. Aerical stainless steel ball indenter of diameter 8.32mmis used for indentation on the

mposites laminate. The tests were conducted with the controlled displacement of theenter (0.2mm / minute). The test data is shown in Table-2.An extensometer is used toasure the displacement of the point just below the indentation location at the bottom of the composite laminate. A 20kN load cell evaluated the load on each compositeinate. The data obtained during test for each laminate is shown in Table-2. The

mposite laminate with different fiber angles is indented for a fixed displacement of 5 mm.damage in the different composite laminate with different fiber angles is shown fig-4.damage area in each composite laminate is observed with the help of optical light

roscope.

SCHEMATIC DIAGRAM OF UTM

00/150 00/300 00/450 00/600 00/900

Fig-1: Schematic diagram of five different laminates

S. No. Specifications ASTM Presentwork

1

Specimen

thickness 46 mm 4 - 5 mm

2Indenterdiameter

1016 mm 8.73 mm

3Cross headdisplacement

1 mm / min0.2 mm /

min

4Indenterdisplacement

510 mm 5 mm

5No of samplesper test

4 4


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ME Page 55

Fig-2: Sequence of angle plies

COMPOSITE LAMINATES WITHOUT E-GLASS POWDER

FRONT SIDE BACK SIDE

0,90

0,60

FRONT SIDE BACK SIDE


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0,45

0,30

0,15

S. No. Angle (0) Max. Load (KN) Indentation (mm) Spring back (mm)


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1 0/15 3.77 0.30 0.92

2 0/30 4.11 0.35 1.17

3 0/45 4.69 0.40 2.50

4 0/60 4.99 0.45 3.08

5 0/90 5.83 0.86 3.44Table - 2: Test results after Indentation.

ph-1: Shows the load carrying capacity in each case for different indenter displacementsmaximum 5mm for all the laminates. It is gradually increasing for the laminates with ther angles varying from (0o/15o)to (0o/90o).

ph-2: Indentation depth is increasing linearly as the fiber angle in laminates is increasingm (0o/15o)to (0o/90o),however it is suddenly increasing in the laminates with fiber angleying from (0o/60o)to (0o/90o).

S. No. Angle ( ) Front face damagearea (mm2)

Back face damagearea (mm2)

1 0/15 971 1256

00.5

11.5

22.5

33.5

44.5

55.5

66.5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5

Load(KN)

Displacement (mm)

15 DEG

30 DEG

45 DEG

60 DEG

90 DEG

0

0.2

0.4

0.6

0.8

1

0 15 30 45 60 75 90 105

Indentation

()

Angle between fibres (Degrees)


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2 0/30 1300 1857

3 0/45 1894 2280

4 0/60 2186 2623

5 0/90 2623 3257

Table-3: Experimental data of damage surface areas on front and back face of the laminates

ph-3: Damage area is increasing with the increase in fiber angle of the laminates in front

and back face of the laminate; however the damage area back face is more than the front

as seen from the above graph.

ph-4: Maximum load taken in each laminate with different fiber angles. The load is increasingarly as the fiber angle is increasing from (0o/15o)to (0o/90o).

0

500

1000

1500

2000

2500

3000

3500

0 15 30 45 60 75 90 105

Front face damage area Back face damage area

00.5

11.5

22.5

33.5

44.5

55.5

66.5

0 15 30 45 60 75 90 105

Load(KN)



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hows spring back effect is increasing in different laminates as the fiber angles are increasing

5o)to (0o/90o), it shows that as the angle between fibers is increasing the laminate elasticity

easing

Material Density

(mg/m3)

Modulus

(G Pa)

Poisons

ratio(v)

Tensile

strength

(G Pa)

E-glass fiber 2.56 76 0.22 3.5

Epoxy resin 1.3 3.6 0.4 0.1

Table-4: Properties of materials

RATE OF LOADING (0.5mm/min) WITH POWDER PARTICULATE

0

0.5

11.5

2

2.5

3

3.5

4

0 15 30 45 60 75 90 105

Sprin

gback(mm)



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RONT SIDE (0/90) BACK SIDE

0.5%

1%

1.5

FRONT SIDE (0/60) BACK SIDE


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0.5%

1%

1.5%



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0.5%

1%

1.5%



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APH 1 : 0-900 FIBRE ORINTATION LAMINATE PROPERTIES( 0.5 mm/min)


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APH 2 : 0-600 FIBRE ORINTATION LAMINATE PROPERTIES( 0.5 mm/min)

APH 3: 0-450 FIBRE ORINTATION LAMINATE PROPERTIES( 0.5 mm/min)

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT (mm)

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT mm

DISPLACEMENT

(mm)

F 0.5

%

F1.0

%

F 1.5

%

0 0 0 0

1 1.92 1.8 1.4

2 3.4 3.1 3.1

3 4.62 4.1 3.5

4 4.85 4.19 3.6

5 4 3.73 3.11

DISPLACEMENT

(mm)

F 0.5

%

F 1.0

%

F 1.5

%

0 0 0 0

1 2 1.7 1.6

2 3.15 3.2 2.95

3 4.65 3.72 3.24 5.4 3.12 2.25

5 3 2.38 1.89


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APH 4: 0-300 FIBRE ORINTATION LAMINATE

OPERTIES( 0.5 mm/min)


0

1

2

3

4

5

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT (mm)

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT (mm)

DISPLACEMENT

(mm)

F

0.5 %

F

1.0 %

F

1.5%

0 0 0 0

1 2.1 2.2 1.7

2 3.8 3.6 3.15

3 4.26 4.2 2.91

4 4.5 2.92 2.29

5 3.5 2.32 1.83

DISPLACEMENT

(mm)

F

0.5 %

F

1%

F

1.5%

0 0 0 0

1 2.15 2.1 1.2

2 3.75 3.5 2.33 5.18 4.2 3.4

4 4.2 3.15 2.85

5 2.5 1.9 1.75


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APH 6 : ANGLE VS DEPTH OF INDENTATION 0.5 mm/min

APH 7 : ANGLE VS PROJECTED HEIGHT 0.5 mm /min

0

1

2

3

4

5

0 2 4 6

F 0.5

F 1

F 1.5

DISPLACEMENT (mm)

0

0.5

1

1.5

2

2.5

3

3.5

0 50 100

DEPTH

0.5%

DEPTH

1.0%

DEPTH1.5%

ANGLE

DISPLACEMENT

(mm)

F 0.5

%

F 1

%

F 1.5

%

0 0 0 0

1 1.9 1.8 1.72 3.1 2.85 2.6

3 3.9 3.8 3.3

4 3 2.8 2.5

5 2.85 2.35 1.7

ANGLE DEPTH

0.5%

DEPTH

1.0%

DEPTH

1.5%

0 0 0 0

15 2.42 2.38 2.67

30 2.6 2.54 2.98

45 2.5 2.6 2.960 2.1 2.4 2.55

90 2 2.17 2.38


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1.5mm/min RATE OF LOADING WITH POWDER

RTICULATE

0

0.5

1

1.5

2

2.5

3

3.5

4

0 20 40 60 80 100

PROJECTED

HEIGHT 0.5 %

PROJECTEDHEIGHT 1.0 %

PROJECTED

HEIGHT 1.5 %

PROJEC

TEDHEIGHT

ANGLE

ANGLE PROJECTED

HEIGHT

(mm) 0.5 %

PROJECTED

HEIGHT

(mm) 1.0 %

PROJECTED

HEIGHT

(mm) 1.5 %

0 0 0 0

15 2.84 3.24 3.31

30 3.2 3.6 3.76

45 2.5 2.7 3.33

60 2.55 3.5 3.67

90 2 2.1 2.6


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APH 9:0-600 FIBRE ORINTATION LAMINATE PROPERTIES(1.5mm/min)


0

1

2

3

4

5

0 2 4 6

F 0.5

F 1.0

F 1.5

(

)

DISPLACEMENT mm

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0F 1.5

DISPLACEMENT (mm)

(

)

DISPLACEMENT

(mm)

F

0.5%

F

1 %

F

1.5%

0 0 0 0

1 1.5 2.05 1.35

2 3.1 3.3 2.75

3 3.2 4.3 1.95

4 2.5 3.75 1.65

5 1.5 3.25 1.31

DISPLACEMENT

(mm)

F

0.5 %

F

1.0 %

F

1.5 %

0 0 0 0

1 2.5 2.31 2.092 4.72 4.22 3.75

3 5.5 4.5 4.2

4 4.5 3.23 2.85

5 3.7 2.96 2.63


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APH 12: 0-150 FIBRE ORINTATION LAMINATE PROPERTIES(1.5 mm/min)

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT (mm)

(

)

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT (mm)

(

)

DISPLACEMENT

(mm)

F 0.5

%

F 1.0

%

F 1.5

%

0 0 0 0

1 2.5 2.31 2.09

2 4.72 4.22 3.753 5.5 4.5 4.2

4 4.5 3.23 2.85

5 3.7 2.96 2.63

DISPLACEMENT

(mm)

F 0.5

%

F 1.0

%

F 1.

%

0 0 0

1 2.5 1.75 12 4.2 3 2

3 5.55 4

4 4.65 2.4

5 3.25 2.2

DISPLACEMENT

(mm)

F 0.5

%

F 1.0

%

F 1.5

%


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APH13 : ANGLE VS DEPTH OF INDENTATION 1.5 mm/min

APH 14 : ANGLE VS PROJECTED HEIGHT (1 .5 mm/ min)

0

1

2

3

4

5

6

0 2 4 6

F 0.5

F 1.0

F 1.5

DISPLACEMENT (mm)

(

)

0

0.5

1

1.5

2

2.5

3

0 50 100

DEPTH

0.5%

DEPTH

1.0%

DEPTH

1.5%

ANGLE

0 0 0

1 1.8 1.98 1.6

2 2.9 3.15 2.

3 4.1 3.9 3.

4 4.85 4.4 2.2

5 3.7 3.2 1.

ANGLE DEPTH

0.5%

DEPTH

1.0%

DEPTH

1.5%

0 0 0 0

15 2.34 2.14 1.9

30 2.45 2.32 2.29

45 2.67 2.6 2.31

60 2.39 2.27 2

90 2.5 2.17 1.8


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HAPTER 5

RESULTS AND DISCUSSION

0

0.5

1

1.5

2

2.5

3

3.5

4

0 20 40 60 80 100

PROJECTEDHEIGHT 0.5%

PROJECTED

HEIGHT 1.0%

PROJECTED

HEIGHT 1.5%

ANGLE

PROJECTEDHEIGHT

ANGLE PROJECTED

HEIGHT

0.5%

PROJECTED

HEIGHT

1.0%

PROJECTED

HEIGHT

1.5%

0 0 0 0

15 3 1.41 2.95

30 2.71 3.65 3.0545 3.19 3.31 3.15

60 3.33 3.32 2.5

90 2.7 2.55 2.1


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raph 1 (0-900 Fibre Orientation of laminate) :

In Graph 1 ,the load carrying capacity is increasing with the decrease incentage of E- glass powder addition. However the load bearing is maximum

0.5% of E-glass powder at a displacement of 4mm at 4.85kN and decrease

the depth of indentation increase at 1.5% of E-glass powder at the

ximum load is at displacement of 4mm at 3.6kN.

aph 2 (0-600 Fibre Orientation of laminate) :

In Graph 2 ,the load carrying capacity is increasing with the decrease in

centage of E- glass powder addition. However the load bearing is maximum

0.5% of E-glass powder at a displacement of 4mm at 5.4kN and decrease as

depth of indentation increase at 1.5% of E-glass powder at the maximum

d is at displacement of 3mm at 3.2kN.


In Graph 3,the load carrying capacity is increasing with the decrease in







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0.5% of E-glass powder at a displacement of 3mm at 5.18kN and decrease

the depth of indentation increase at 1.5% of E-glass powder at theximum load is at displacement of 3mm at 3.4kN.







aph 6 (Angle vs Depth of indentation) :

In graph 6,Depth of indentation is increasing with increase in percentage

E-glass powder and however with increasing of fibre angle 0-150 to 0-300

er on there is increase in depth of indentation,but it is decreases with

gles 0-300 to 0-900.

aph 7 (Angle vs projected height) :

In graph 7, Projected height is increasing with fibre angles(0-300 )and

rease in percentage of (0-300 to 0-450),later on increasing 0-450 to 0-600

d increasing in percentage of E-glass powder and however with increasing


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angle,Increase in projecetd height but it gradually fluctuates after 0-150 to

00 angles.

raph 8(0-90

0

Fibre Orientation of laminate) :





d is at displacement of2 mm at 2.75kN.














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Documents

Major Project Document