The study of impact behavior of composite laminate by varying fiber orientation and stacking sequence

CONTENTS

Sr. No. Topics

List of tables

List of figures

Abstract

CHAPTER 1. INTRODUCTION
Introduction

CHAPTER 2. BACKGROUND
2.1. Composite Material
2.2. Classification of Composite Material
2.3. Laminates
2.4. Properties of Composite Material
2.5. Advantages
2.6. Disadvantages
2.7. Applications

CHAPTER 3. LITERATURE REVIEW
Literature Review

CHAPTER 4. PROBLEM STATEMENT
4.1 Problem Statement
4.2 Objective of Work

CHAPTER 5. EXPERIMENTAL PROCEDURE
5.1 Selection of Material
5.1.1 Glass Fiber
5.1.2 Resin
5.1.3 Hardener
5.1.4 P.V.A
5.1.5 Wax
5.2 Tools Used
5.3 Specimen Geometry
5.4 Fabrication of Plates
5.4.1 Mixing Ratio
5.4.2 Hand Layup Technique
5.4.3 Stacking Sequence
5.4.4 Prepared Plate
5.5 Impact Test
5.5.1 Charpy Impact Test
5.5.2 Impact Testing Procedure
5.5.3 Testing of Plates
5.5.4 Observation Table

CHAPTER 6. ANALYSIS OF PLATES BY “ANSYS 14.5”
6.1 Loading and boundary conditions
6.2 Analysis Results
6.3 Observations Table

CHAPTER 7. COMPARATIVE RESULTS
Comparative Results

CHAPTER 8. RESULT AND DISCUSSIONS
Result and Discussions

CHAPTER 9. CONCLUSION
Conclusion
REFERENCES

List of figures

Fig.2.1 Particle reinforced composites

Fig.2.2 Long (continuous) and short (discontinuous) fibers

Fig.2.3 Flake composites

Fig.2.4 Lamina and laminate layups

Fig.5.1 Different Glass FiberOrientations

Fig.5.2 NETPOL 1011 (General Purpose Polyester Resin)

Fig.5.3 Hardener

Fig.5.4 Wax

Fig.5.5 Different kinds of tools used

Fig.5.6 Design of specimen

Fig.5.7 Finally prepared composite plates with v-notch

Fig.5.8 Impact Testing Machine

Fig.5.9 working diagram of Charpy impact testing

Fig.5.10 Specimen before and after failure

Fig.5.11 Impact Energy of Different Plates

Fig.6.1 Loading and boundary conditions

Fig.6.2 Analysis of Plate No. 01

Fig.6.3 Analysis of Plate No. 03

Fig.6.4 Analysis of Plate No. 03

Fig.6.5 Analysis of Plate No. 04

Fig.6.6 Analysis of Plate No. 05

Fig.6.7 Analysis of Plate No. 06

Fig.6.8 Analysis of Plate No. 07

Fig.6.9 Analysis of Plate No. 08

Fig.6.10 Analysis of Plate No. 09

Fig.6.11 Analysis of Plate No. 10

Fig.6.12 Impact Energy of Different Plates in ANSYS

Fig.7.1 Graphical Comparison Between Experimental and ANSYS

List of tables

Table 5.1 Typical properties of different glass fibers

Table 5.2 Stacking Sequences

Table 5.3 Impact Energy of Different Plates

Table 6.1 Impact Energy of Different Plates in ANSYS

Table 7.1 Comparative Results Between Experimental and ANSYS

ABSTRACT

Glass fiber reinforced polymer composites are one of the most important engineering material required for variety of sophisticated application in modern industry. The two components of FRP composite are matrix and reinforcement as glass fibers. The mechanical properties of FRP composite material depend on mainly an orientation, amount and type of fiber reinforcement which is present in it.

In present work, the effect of various fibers orientation such as 0°/90°, ±45°, 0°/±45° on mechanical properties of FRP composite laminates has been studied. The dimensions of various plates are taken as per ASTM standard. The material selected is glass fiber and general purpose resin. The composite plates with different fiber orientations and stacking sequence is fabricated using ‘Hand Layup Technique’. The work objective is to find toughness of composite laminate by varying fiber orientations. The impact strength of 10 samples are investigated by using Charpy impact test. Lastly the experimental results obtained from test is used to verify and developed finite element model and ANSYS result describing a composite plate under impact load.

1. INTRODUCTION

Many of our modern technologies require materials with unusual combinations of properties that cannot be met by the conventional metal alloys, ceramics, and polymeric materials. This is especially true for materials that are needed for aerospace, underwater, and transportation applications. For example, aircraft engineers are increasingly searching for structural materials that have low densities, are strong, stiffer, and abrasion and impact resistant, and are not easily corroded. This is a rather formidable combination of characteristics. Frequently, strong materials are relatively dense; also, increasing the strength or stiffness generally results in a decrease in impact strength.[6]

A composite material can be defined as a combination of two or more materials that results in better properties than those of the individual components used alone. In contrast to metallic alloys, each material retains its separate chemical, physical, and mechanical properties.[15]

Charpy impact testing is a low-cost and reliable test method. The specimen is relatively easy to prepare, many specimens can be prepared at one time, various specimen orientations can be tested, and relatively low cost equipment is used to test the specimen.

Some of the inherent advantages of composite materials over traditional materials are: (1) superior thermo-mechanical properties such as high strength and stiffness, and light weight, (2) excellent corrosion resistance, (3) high strength to weight ratio (4) design flexibility (tailor ability), and (5) longterm durability under harsh service environments.

2. BACKGROUND

2.1 Composite Material

A composite material is a material in which two or more distinct materials are combined together but remain uniquely identifiable in the mixture. The most common example is, perhaps, fiberglass, in which glass fibers are mixed with a polymeric resin. If one were to cut the fiberglass and, after suitable preparation of the surface, look at the material, the glass fibers and polymer resin would be easy to distinguish. This is not the same as making an alloy by mixing two distinct materials together where the individual components become indistinguishable. An example of an alloy that most people are familiar with is brass, which is made from a mixture of copper and zinc. After making the brass by melting the copper and zinc together and solidifying the resultant mixture, it is impossible to distinguish either between or where the atoms of copper and zinc are. There are many composite materials and while we may be aware of some, such a fiberglass and carbon epoxy, there are many others ranging from the mundane, reinforced concrete ( a mixture of steel rod and concrete itself a composite of rock particles and cement), pneumatic tires (steel wires in vulcanized rubber), many cheap plastic moldings (polyurethane resin filled with ceramic particles such as chalk and talc) to the exotic metal matrix composites used in the space program (metallic titanium alloys reinforced with SiC ceramic fibers), and your automobile, such as engine pistons (aluminum alloys filled with fibrous alumina) and brake discs (aluminum alloys loaded with wear resistant SiC particles). Regardless of the actual composite, the two [or more] constituent materials that make up the composite are always readily distinguished when the material is sectioned or broken.[5]

2.2 Classification of Composite Material

A]. According to geometry of reinforcing phase:

(a) Particle reinforced composites

Particulate compositescomprises of particles immersed in matrices such as alloys and ceramics. They are usually isotropic since the particles are added randomly. Particulate composites have advantages such as improved strength, increased operating temperature and oxidation resistance etc. Typical examples are use of aluminum particles in rubber, silicon carbide particles in aluminum and gravel, sand & cement to make concrete.[6]

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Fig.2.1Particle reinforced composites[6]

(b) Fiber composites:

Fiber compositesconsist of matrices reinforced by short (discontinuous) or long (continuous) fibers. Fibers are generally anisotropic and examples include carbon and aramids. Examples of matrices are resins such as epoxy, metals such as aluminum and ceramics such as calciumalumino silicate. The reinforcement of continuous fiber matrix composite are unidirectional or woven fiber laminas. Laminas are stacked on top of each other at various angles to form a multidirectional laminate.[6]

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Fig.2.2 Long (continuous) and short (discontinuous) fibers.[6]

(c) Flake composites:

Flake composites consist of flat reinforcements of matrices. Typical flake materials are glass, mica, aluminum and silver. Flake composites provide advantages such as higher strength and low cost. However, flakes are difficult to orient and only a limited number of materials are available for use.[6]

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Fig.2.3 Flake composites[6]

B]. According to type of matrix used:

(a) Polymer Matrix Composites (PMCs)

The most common and popular advanced composites are polymer matrix composites. These composites consist of a polymer (e.g. epoxy, polyester, etc.) reinforced by thin-diameter fibers (e.g. glass, graphite, aramid). They have a high strength to weight ratio. For example graphite/epoxy composites are approximately five times stronger than steel on a weight- for weight basis. The reasons for their popularity are low cost, high strength to weight ratio, simple manufacturing principles and ease of fabrication. The main drawbacks of PMCs include low operating temperatures depending on the polymer used as matrix, high coefficient of thermal, moisture expansion, and low elastic properties in certain directions. Applications of PMCs range from tennis racquets to the space shuttle.[6]

(b) Metal Matrix Composites (MMCs)

MMCs have a metal matrix. Examples of matrices in such composites include aluminum, magnesium and titanium. Typical fibers include carbon and silicon carbides. Metals are mainly reinforced to increase or decrease their properties to suit the needs of design. For example, the elastic stiffness and strength of metals can be increased whereas large coefficients of thermal expansion and thermal and electrical conductivities of metals can be reduced by the addition of fibers such as silicon carbide. MMCs are mainly used to provide advantages over monolithic metals such as steel and aluminum. MMCs have several advantages over PMCs, like, higher elastic properties, high service temperature, insensitivity to moisture, and better wear & fatigue resistance. However Reinforcing metals with fibers reduce ductility and fracture toughness. It is also costly and requires complex fabrication techniques compared to PMC‘s.[6]

(c) Ceramic Matrix Composites (CMCs)

CMCs have a ceramic matrix such as alumina, calcium alumino silicate reinforced by fibers such as carbon or silicon carbide. Advantages of CMCs are high strength, hardness, high service temperature limits for ceramics (1500 ° C), chemical inertness and low density. Reinforcing ceramics with fibers, such as silicon carbide or carbon, increases their fracture toughness as it causes gradual failure of composite. CMCs are finding increased application in high temperature areas where MMCs and PMCs cannot be used. Typical applications include cutting tool inserts in oxidizing and high temperature environments especially in space applications.[6]

(d) Carbon-Carbon Composites (CCCs)

Carbon-Carbon Composites have carbon fiber in a carbon matrix. CCCs are used in very high temperature environments of up to 3315 ° C, and are 20 times stronger and 30% lighter than graphite fibers. Reinforcement of a carbon matrix allows the composite to fail gradually, and gives advantages such as ability to withstand high temperatures, low creep at high temperatures, low density, good tensile and compressive strengths, high fatigue resistance and high thermal conductivity. The main uses of CCCs are Space shuttle nose cones; Aircraft and formula one brake and mechanical fasteners required for high temperature applications.[6]

2.3 Laminates

When there is a single ply or a lay-up in which all of the layers or plies are stacked in the same orientation, the lay-up is called a lamina. When the plies are stacked at various angles, the lay-up is called a laminate. Continuous-fiber composites are normally laminated materials (Fig. 1.8) in which the individual layers, plies, or laminaare oriented in directions that will enhance the strength in the primary load direction. Unidirectional (0°) lamina are extremely strong and stiff in the 0° direction.[15]

Abbildung in dieser Leseprobe nicht enthalten

Fig.2.4 Lamina and laminate layups[15]

2.4 Properties of Composite Material

1. Low density.
2. Increased design flexibility.
3. Better damage tolerance.
4. Increased impact resistance.
5. Increased fracture toughness.
6. Greater scuff resistance.
7. High specific strength.
8. High specific modulus.
9. High thermal conductivity.
10. Good fatigue modulus.
11. Control of thermal expansion.
12. High abrasion and wear resistance.
13. Good anticorrosion.
14. Potentially lower component costs.
15. Lower fabrication cots.
16. Lower quality assurance costs.
17. Integral construction of composite structures.

2.5 Advantages of Composite Material

1. High strength or stiffness to weight ratio. As enumerated above, weight savings are significant ranging from 25-45% of the weight of conventional metallic designs.
2. Due to greater reliability, there are fewer inspections and structural repairs.
3. Fiber to fiber redundant load path.
4. Improved dent resistance is normally achieved. Composite panels do not sustain damage as easily as thin gage sheet metals.
5. It is easier to achieve smooth aerodynamic profiles for drag reduction.
6. Complex double-curvature parts with a smooth surface finish can be made in one manufacturing operation.
7. Composites offer improved torsional stiffness. This implies high whirling speeds, reduced number of intermediate bearings and supporting structural elements.
8. The overall part count and manufacturing & assembly costs are thus reduced.
9. High resistance to impact damage.
10. Like metals, thermoplastics have indefinite shelf life.
11. Composites are dimensionally stable i.e. they have low thermal conductivity and low coefficient of thermal expansion.
12. Composite materials can be tailored to comply with a broad range of thermal expansion design requirements and to minimize thermal stresses.
13. Improved friction and wear properties.

2.6 Disadvantages of Composite Material

1. Use of composites is more challenging, materials are less predictable.
2. Structural health monitoring and nondestructive inspection of composites is much more difficult than for metals.
3. One of the most common types of layered composite failure is delamination, i.e. debonding of one layer from another.
4. Composites are more brittle than wrought metals and thus are more easily damaged.
5. Transverse properties may be weak.
6. Reuse and disposal may be difficult.
7. Repair introduces new problems, for the following reasons: Hot curing is necessary in many cases, requiring special equipment. Curing either hot or cold takes time.
8. The job is not finished when the last rivet has been installed.
9. Analysis is difficult because of highly non-linear behaviour.
10. Matrix is subject to environmental degradation.
11. Materials require refrigerated transport and storage and have limited shelf lives.

2.7 Application

1. Composite Grids/ Gratings
2. Aqueous Piping System
3. Water & fuel storage tanks, Vessels
4. Low pressure composite valves
5. Modular paneling for partition walls
6. Sub – sea structural components
7. Boxes, housings and shelters
8. Fire water pump casing & sea water lift pump casing
9. Blast & Fire protection
10. Third rail covers for underground railway
11. Structures for overhead transmission lines for railway
12. Power line insulators
13. Lightning poles
14. To make toys, boats, garden equipments

3. LITERATURE REVIEW

[1] CameliaCerbu, et.al. [1] Studied that how to improve dynamic properties (resilience K) of the polymeric composites reinforced with E-glass woven fabric, one may recommend the using of the supplementary reinforcement with E-glass chopped fibres. This method should be used in case of every other polymeric composite reinforced with woven fabrics to improve dynamic properties.

[2] Mohd. A. Fahmy, et.al. [2] Proposed that mechanical behaviour of composite material like glass fiber (E-Glass) is used as reinforcement in the form of unidirectional fibers with epoxy resin as matrix for the laminated composite beams. For analytical models, their associate material elastic properties were calculated analytically using the simple rule-of-mixtures. It is found that changes in fiber angle as well as laminate stacking sequences yield to different dynamic behaviour of the component and different fiber orientations in order to get more (or less) structure stiffness. In practical applications, he found that if a natural frequency excites the structure and the material property change by the laminate stacking sequence, instead of re-design the complete structure.

[3] K. Vasantha Kumar, et.al. [3]This work investigates that the effects of angle ply orientation on tensile properties of a woven fabric bi-directional composite laminate experimentally. For that the most common method found to determine these constants is static testing. For composite materials, ten types of specimens with different stacking sequences i.e., (±0°, ±10°, ±30°, ±40°, ±45°, ±55°, ±65°, ± 75°, and ±90°) are fabricated. And observed from the results that glass/Epoxy with 0° fiber orientation Yields’ high strength, stiffness and load carrying capacity than any other orientation. Hence, it is suggested that fiber orientation with 0° is preferred for designing of structures like which is more beneficial.

[4] Satnam Singh, et.al. [4]The present work focuses on determination of mechanical properties of pure epoxy and random oriented glass fiber (mat) reinforced epoxy at 10% and 20% weight fractions of glass fibers prepared a specimen according to ASTM standards and test. The experimental results revealed that with increase in weight fraction of reinforcement, the tensile strength and flexural strength increased by 14.5 % and 123.65% for 20 % glass reinforced composites over pure epoxy. The numerical results obtained were in good agreement to the experimental results. However increased reinforcement increases the brittleness of material which may results in low impact strength.

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