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207682663-Composite-Material-An-Introduction.pptx

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Abinash Behera
Abinash Behera

The document provides an introduction to composite materials, including: 1. A brief history of composite materials from natural occurrences to modern developments. 2. A definition of composite materials as a combination of two materials and a basic composition of a composite including a matrix and reinforcements. 3. A classification of composites based on the matrix phase (polymer, metal, ceramic) and the type of reinforcements used (fibers, particulates, flakes, whiskers). 4. An overview of how to characterize the mechanical properties of composites including rule of mixtures, loading orientation, and methods to estimate properties like modulus of elasticity, strength, and thermal expansion.

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Introduction to Composite Materials By Bishwaraj Bhattarai Institute Roll No 10/ME/134 Bishwaraj.Bhattarai@Outlook.com Setobaadal@Gmail.com
Table of Contents 1 #. WHY STUDY COMPOSITE MATERIALS ? 1. Inception and History General Overview, Natural Occurrence and Anthropogenic History 2. Introduction Technical Definition Composition 3. Classification Based on Matrix Phase Based on Reinforcements 4. Mechanical Characterization Rule of Mixture and Loading Orientation Estimation of Various Properties 5. Advantages of Composite Materials 6. Disadvantages of Composite Materials 7. Conclusion
2 Why Study Composite Materials ??? Lets take a closer look at our lives.
3 Why Study contd. Composites make a great proportion of most of the materials we use in our daily lives The use is ever increasing which makes it a must to understand and explore these materials THATS WHY .
1. Inception and History of Composite Materials 4 Composite Material = Combination of two materials Natural Occurrences 1. Trees = Cellulose Fibers + Lignin (natural Polymer) 2. Muscles 3. Bones 4. Silky thread made by spider Anthropogenic History Wood is the oldest known composite used by human beings Straw Bricks as construction material, ~ 10000 BC ( Ashby et al) Modern development began before World War II with requirement of strong but light material Glass Fiber Reinforced Plastic was the first commercial Composite used in Havilland Mosquito Bomber aircraft of Royal British Navy force
2. Introduction to Composite Materials 5 Definition Combination of 2 different materials at macroscopic level Identity of each component is retained Composites Vs. Alloys Basic Composition Composite = Ground Substance (Matrix Phase) + Reinforcements (Mostly Fibers) Fig 1: Basic Components of a Composite Various combinations of Matrix and Reinforcing Materials can be used as per the requirement of various properties and the uses Various types based on various matrix and reinforcement materials
6 3. Classification of Composite Materials A. Based on Matrix Phase: Polymer/Metal/Ceramic 1. Polymer Matrix Composite, PMC Matrix is made from a Polymer like Resins The first commercial composite, Glass Fiber, was a PMC made with Phenolic Resin May be a. Thermosetting ~ Epoxy Resin OR b. Thermoplastic ~ Polycarbonate, PVC, Nylon, Polystyrene Light Weight Easy Processing Excellent Mechanical Properties Extensive use in Automobile and Aeronautical Industries 2. Metal Matrix Composite, MMC Use metals like Aluminum, Magnesium, Iron, Cobalt etc. as matrix phase Provide additional Strength, Fracture Toughness and Stiffness than PMC Popular in Mobile Phone industries
3.A Classification/Matrix Phase contd. 3. Ceramic Matrix Composite, CMC Use Ceramic materials as the matrix phase and reinforce with short fibers derived from Silicon Carbide, Boron Nitride, etc. High Melting Point Stability at elevated temperature ( ~ 1500 oC ) Corrosion Resistant High Compressive Strength 7 Favorite choice for working in high temperature environment X However they are quite brittle compared to PMCs B. Classification Based on Reinforcement Materials: Fibers/Particulates/Flakes/Whiskers 1. Fiber Reinforcement Fibers made from various materials are placed within the matrix phase to form a composite of desired strength/properties Fibers form the major load carrying element and are most common reinforcement
3.B Classification/By Reinforcement/Fibers . Contd. 8 3.B.1 Fiber Reinforcement: Types of Fiber Reinforcement A. Continuous/Long Fiber Long, continuous and unbroken fibers are used with L/D > 100 Most common type of composite materials Fibers may be oriented unidirectional or bidirectional Better impact resistance and rigidity at elevated, sub zero temperatures Modulus retention at elevated temperature Creep resistance Dimensional stability during solidification (thermoplastics used as matrix phase) B. Short/Chopped Fibers Chopped or small pieces of fibers are used instead of long, continuous fibers L/D ratio is within 100 Common Fiber Materials A. Carbon/Graphite B. Glass C. Aramid D. Boron Fig-2: Fiber Composite
3.B.1 Classification/Based on Reinforcement/Fibers/ Common Fiber Materials. Contd. 9 A. Carbon/Graphite Fibers Fibers are made from carbon/graphite material, commonly derived from Polyacrylonitrile Excellent fatigue resistance and do not undergo stress rupture like glass fibers High electrical conductivity, due to conductive nature of Carbon, thus used for applications requiring good electrical properties B. Glass Fiber Glass is the most common reinforcement material for PMC Common variants are E-glass, R-glass, S-glass, D-glass, ECR-glass etc. Configuration may be Roving, Sheet Moulding, Woven Roving, Chopped Strand Mat etc. High Tensile Strength X Lower Modulus compared to other fibers C. Aramid Fiber Kevlar is a common aramid fiber composite Highest strength to weight ratio among all commercial composites Similar tensile strength but at least twice modulus compared to glass fibers High Toughness X Lower compression strength, poor adhesion to matrix
1 0 3.B.1 Classification/By Reinforcement/Fiber/Fiber Materials .. Contd. D. Boron Fibers Has been in use much before the use of Carbon fibers began High cost led to gradual reduction in their except for specific purposes Similar tensile strength to glass fibers but very high modulus, up to 5 times higher Composite has higher stiffness 3.B.2 Particulate Reinforcement Reinforcement in form of particles which are of order of few microns in diameter Use of particles increases modulus and decreases ductility of matrix material Load is shared by both particle and matrix, majority by particles E.g. Automobile type Carbon Black (particulate)+Rubber (matrix) Fig 3: Particulate
11 3.B. Classification/By Reinforcement .Contd. 3.B.3 Flakes Fig 4: Flake Composite Flakes refer to small, flat (i.e. 2D geometry) layer or chips Very effective reinforcement as they impart almost equal strength in all the directions They can be packed very densely when laid parallel, that is denser than the longitudinal fibers Aluminum flakes are used in paints, they align themselves parallel to surface of the coating and impart good properties 3.B.4 Whiskers Single crystal fibers; short, discontinuous and with polygonal section Fig 5: Microscopic view of Whiskers Fig 6: Whisker Composite
12 4. Mechanical Characterization : Composites 4.1 Introduction Estimation of mechanical properties of composite is a bit complex compared to metals as they are anisotropic and the properties vary with directions Structural analysis involves more parameters (like Stiffness/Strength Constants) than the analysis of metals. Mechanical characterization of composites is still under development, with many existing methods under debate. 4.2 Loading Orientation and Rule of Mixture A. Loading Orientation Load may be Iso Strain : Load aligned with fibers OR Iso Stress : Load transverse to the fibers Fig 7: (a) Iso Strain Load (b) Iso
13 4.2 Mechanical Characterization . Contd. B. Rule of Mixture Its an approach to estimate the mechanical properties of composite materials Property of composite is the volume weighed average of the properties of the constituents matrix and the dispersed phases Some of the properties may depend on loading direction and vary for Iso Strain and Iso Stress conditions, while other properties are same for both the loading conditions 4.3 Estimation of various Mechanical Properties of the Composites 1. Density dc = dm . Vm + df . Vf dc ,dm,df densities of the composite, matrix and dispersed phase respectively; Vm ,Vf volume fraction of the matrix and dispersed phase
14 4.3 Mechanical Characterization/Mechanical Properties Contd. 2. Coefficient of Thermal Expansion A. Iso-Strain/Parallel to fibers 留c =( 留m . Em .Vm + 留f . Ef . Vf ) / (Em . Vm + Ef Vf ) 留c , 留m , 留f Coefficient of thermal expansion of composite in longitudinal direction, matrix and dispersed phase (fiber) respectively; Em , Ef Modulus of elasticity of matrix and dispersed phase (fiber) respectively. B. Iso-Stress/Transverse to Fibers 留ct = (1+亮m) 留m . Vm + 留f . Vf 亮m - Poissons ratio of matrix 留ct Coefficient of thermal expansion in transverse direction
15 4.3 Mechanical Properties . Contd. 3. Modulus of Elasticity A. Iso Strain Condition Ec = Em . Vm + Ef . Vf B. Iso Stress Condition 1/Ect = Vm/Em + Vf/Ef C. Short Fibers Ecl = 侶o . 侶l . Vf . Ef + Vm . Em 侶l = 1 2 / (硫L) . tan h(硫L / 2 ) 硫 =[ 8Gm / ( Ef . D2 . ln ( 2 R/ D))]1/2 Ef - Modulus of elasticity of matrix materials 侶o - 0.0 align in transverse direction Gm - Shear modulus of matrix material 侶o - 1/5 random orientation in any direction ( 3D ) 侶l - Length correction factor 侶o - 3/8 random orientation in any direction (2D) L - Fibers length 侶 - 遜 bi- axial parallel to the fibers
16 4.3 Mechanical Properties Cont. 4. Sheer Modulus Gc = Gf . Gm / ( Vf . Gm + Vm . Gf ) Gf - shear modulus of elasticity of fiber material Gm - shear modulus of elasticity of matrix material Gc - shear modulus of elasticity of composite 5. Poissons Ratio 袖 = Vf . 袖f + Vm . 袖m 袖f - Poissons ratio of fiber materials 袖m - Poissons ratio of matrix materials 袖 - Poissons ratio of composite
17 4.3. Mechanical Properties . Contd. 6. Tensile Strength A. Long Fiber c = m . Vm + f . Vf c , m, f - tensile strength of the composite ,matrix and dispersed phase (fiber) respectively B. Short Fiber c = m . Vm + f . Vf . ( 1 Lc/ 2L ) for length less then critical length, Lc c = m*Vm + L* c*Vf/d for length more than critical length L c = f * d / Tc d - diameter of fiber Tc - shear strength of the bond between the matrix and dispersed phase L - length of the fiber
18 5. Advantages of Composite Materials High Strength to Weight Ratio Light Weight Design Flexibility, to achieve desired stiffness, strength and manufacturing requirements Complex shapes are easily accomplished Fire Resistance Chemical and weathering Resistance Resistance to fatigue damage with good damping properties Low thermal conductivity
19 5. Disadvantages High Manufacturing Cost. A typical finished composite may cost in between 10-15 times (or even more) the cost of material being used. Synthetic fibers have low melting point and thus high temperature operation is not feasible for those type of composite Repairs of composites is very difficult and complicated, unlike metal based components Sometimes, critical flaws and cracks in the composite structure may go unnoticed 6. Conclusion A field of heave research and development Development of new types and obtaining the desired properties is the main focus Attempts are being made to reduce the manufacturing cost
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207682663-Composite-Material-An-Introduction.pptx

  • 1. Introduction to Composite Materials By Bishwaraj Bhattarai Institute Roll No 10/ME/134 Bishwaraj.Bhattarai@Outlook.com Setobaadal@Gmail.com
  • 2. Table of Contents 1 #. WHY STUDY COMPOSITE MATERIALS ? 1. Inception and History General Overview, Natural Occurrence and Anthropogenic History 2. Introduction Technical Definition Composition 3. Classification Based on Matrix Phase Based on Reinforcements 4. Mechanical Characterization Rule of Mixture and Loading Orientation Estimation of Various Properties 5. Advantages of Composite Materials 6. Disadvantages of Composite Materials 7. Conclusion
  • 3. 2 Why Study Composite Materials ??? Lets take a closer look at our lives.
  • 4. 3 Why Study contd. Composites make a great proportion of most of the materials we use in our daily lives The use is ever increasing which makes it a must to understand and explore these materials THATS WHY .
  • 5. 1. Inception and History of Composite Materials 4 Composite Material = Combination of two materials Natural Occurrences 1. Trees = Cellulose Fibers + Lignin (natural Polymer) 2. Muscles 3. Bones 4. Silky thread made by spider Anthropogenic History Wood is the oldest known composite used by human beings Straw Bricks as construction material, ~ 10000 BC ( Ashby et al) Modern development began before World War II with requirement of strong but light material Glass Fiber Reinforced Plastic was the first commercial Composite used in Havilland Mosquito Bomber aircraft of Royal British Navy force
  • 6. 2. Introduction to Composite Materials 5 Definition Combination of 2 different materials at macroscopic level Identity of each component is retained Composites Vs. Alloys Basic Composition Composite = Ground Substance (Matrix Phase) + Reinforcements (Mostly Fibers) Fig 1: Basic Components of a Composite Various combinations of Matrix and Reinforcing Materials can be used as per the requirement of various properties and the uses Various types based on various matrix and reinforcement materials
  • 7. 6 3. Classification of Composite Materials A. Based on Matrix Phase: Polymer/Metal/Ceramic 1. Polymer Matrix Composite, PMC Matrix is made from a Polymer like Resins The first commercial composite, Glass Fiber, was a PMC made with Phenolic Resin May be a. Thermosetting ~ Epoxy Resin OR b. Thermoplastic ~ Polycarbonate, PVC, Nylon, Polystyrene Light Weight Easy Processing Excellent Mechanical Properties Extensive use in Automobile and Aeronautical Industries 2. Metal Matrix Composite, MMC Use metals like Aluminum, Magnesium, Iron, Cobalt etc. as matrix phase Provide additional Strength, Fracture Toughness and Stiffness than PMC Popular in Mobile Phone industries
  • 8. 3.A Classification/Matrix Phase contd. 3. Ceramic Matrix Composite, CMC Use Ceramic materials as the matrix phase and reinforce with short fibers derived from Silicon Carbide, Boron Nitride, etc. High Melting Point Stability at elevated temperature ( ~ 1500 oC ) Corrosion Resistant High Compressive Strength 7 Favorite choice for working in high temperature environment X However they are quite brittle compared to PMCs B. Classification Based on Reinforcement Materials: Fibers/Particulates/Flakes/Whiskers 1. Fiber Reinforcement Fibers made from various materials are placed within the matrix phase to form a composite of desired strength/properties Fibers form the major load carrying element and are most common reinforcement
  • 9. 3.B Classification/By Reinforcement/Fibers . Contd. 8 3.B.1 Fiber Reinforcement: Types of Fiber Reinforcement A. Continuous/Long Fiber Long, continuous and unbroken fibers are used with L/D > 100 Most common type of composite materials Fibers may be oriented unidirectional or bidirectional Better impact resistance and rigidity at elevated, sub zero temperatures Modulus retention at elevated temperature Creep resistance Dimensional stability during solidification (thermoplastics used as matrix phase) B. Short/Chopped Fibers Chopped or small pieces of fibers are used instead of long, continuous fibers L/D ratio is within 100 Common Fiber Materials A. Carbon/Graphite B. Glass C. Aramid D. Boron Fig-2: Fiber Composite
  • 10. 3.B.1 Classification/Based on Reinforcement/Fibers/ Common Fiber Materials. Contd. 9 A. Carbon/Graphite Fibers Fibers are made from carbon/graphite material, commonly derived from Polyacrylonitrile Excellent fatigue resistance and do not undergo stress rupture like glass fibers High electrical conductivity, due to conductive nature of Carbon, thus used for applications requiring good electrical properties B. Glass Fiber Glass is the most common reinforcement material for PMC Common variants are E-glass, R-glass, S-glass, D-glass, ECR-glass etc. Configuration may be Roving, Sheet Moulding, Woven Roving, Chopped Strand Mat etc. High Tensile Strength X Lower Modulus compared to other fibers C. Aramid Fiber Kevlar is a common aramid fiber composite Highest strength to weight ratio among all commercial composites Similar tensile strength but at least twice modulus compared to glass fibers High Toughness X Lower compression strength, poor adhesion to matrix
  • 11. 1 0 3.B.1 Classification/By Reinforcement/Fiber/Fiber Materials .. Contd. D. Boron Fibers Has been in use much before the use of Carbon fibers began High cost led to gradual reduction in their except for specific purposes Similar tensile strength to glass fibers but very high modulus, up to 5 times higher Composite has higher stiffness 3.B.2 Particulate Reinforcement Reinforcement in form of particles which are of order of few microns in diameter Use of particles increases modulus and decreases ductility of matrix material Load is shared by both particle and matrix, majority by particles E.g. Automobile type Carbon Black (particulate)+Rubber (matrix) Fig 3: Particulate
  • 12. 11 3.B. Classification/By Reinforcement .Contd. 3.B.3 Flakes Fig 4: Flake Composite Flakes refer to small, flat (i.e. 2D geometry) layer or chips Very effective reinforcement as they impart almost equal strength in all the directions They can be packed very densely when laid parallel, that is denser than the longitudinal fibers Aluminum flakes are used in paints, they align themselves parallel to surface of the coating and impart good properties 3.B.4 Whiskers Single crystal fibers; short, discontinuous and with polygonal section Fig 5: Microscopic view of Whiskers Fig 6: Whisker Composite
  • 13. 12 4. Mechanical Characterization : Composites 4.1 Introduction Estimation of mechanical properties of composite is a bit complex compared to metals as they are anisotropic and the properties vary with directions Structural analysis involves more parameters (like Stiffness/Strength Constants) than the analysis of metals. Mechanical characterization of composites is still under development, with many existing methods under debate. 4.2 Loading Orientation and Rule of Mixture A. Loading Orientation Load may be Iso Strain : Load aligned with fibers OR Iso Stress : Load transverse to the fibers Fig 7: (a) Iso Strain Load (b) Iso
  • 14. 13 4.2 Mechanical Characterization . Contd. B. Rule of Mixture Its an approach to estimate the mechanical properties of composite materials Property of composite is the volume weighed average of the properties of the constituents matrix and the dispersed phases Some of the properties may depend on loading direction and vary for Iso Strain and Iso Stress conditions, while other properties are same for both the loading conditions 4.3 Estimation of various Mechanical Properties of the Composites 1. Density dc = dm . Vm + df . Vf dc ,dm,df densities of the composite, matrix and dispersed phase respectively; Vm ,Vf volume fraction of the matrix and dispersed phase
  • 15. 14 4.3 Mechanical Characterization/Mechanical Properties Contd. 2. Coefficient of Thermal Expansion A. Iso-Strain/Parallel to fibers 留c =( 留m . Em .Vm + 留f . Ef . Vf ) / (Em . Vm + Ef Vf ) 留c , 留m , 留f Coefficient of thermal expansion of composite in longitudinal direction, matrix and dispersed phase (fiber) respectively; Em , Ef Modulus of elasticity of matrix and dispersed phase (fiber) respectively. B. Iso-Stress/Transverse to Fibers 留ct = (1+亮m) 留m . Vm + 留f . Vf 亮m - Poissons ratio of matrix 留ct Coefficient of thermal expansion in transverse direction
  • 16. 15 4.3 Mechanical Properties . Contd. 3. Modulus of Elasticity A. Iso Strain Condition Ec = Em . Vm + Ef . Vf B. Iso Stress Condition 1/Ect = Vm/Em + Vf/Ef C. Short Fibers Ecl = 侶o . 侶l . Vf . Ef + Vm . Em 侶l = 1 2 / (硫L) . tan h(硫L / 2 ) 硫 =[ 8Gm / ( Ef . D2 . ln ( 2 R/ D))]1/2 Ef - Modulus of elasticity of matrix materials 侶o - 0.0 align in transverse direction Gm - Shear modulus of matrix material 侶o - 1/5 random orientation in any direction ( 3D ) 侶l - Length correction factor 侶o - 3/8 random orientation in any direction (2D) L - Fibers length 侶 - 遜 bi- axial parallel to the fibers
  • 17. 16 4.3 Mechanical Properties Cont. 4. Sheer Modulus Gc = Gf . Gm / ( Vf . Gm + Vm . Gf ) Gf - shear modulus of elasticity of fiber material Gm - shear modulus of elasticity of matrix material Gc - shear modulus of elasticity of composite 5. Poissons Ratio 袖 = Vf . 袖f + Vm . 袖m 袖f - Poissons ratio of fiber materials 袖m - Poissons ratio of matrix materials 袖 - Poissons ratio of composite
  • 18. 17 4.3. Mechanical Properties . Contd. 6. Tensile Strength A. Long Fiber c = m . Vm + f . Vf c , m, f - tensile strength of the composite ,matrix and dispersed phase (fiber) respectively B. Short Fiber c = m . Vm + f . Vf . ( 1 Lc/ 2L ) for length less then critical length, Lc c = m*Vm + L* c*Vf/d for length more than critical length L c = f * d / Tc d - diameter of fiber Tc - shear strength of the bond between the matrix and dispersed phase L - length of the fiber
  • 19. 18 5. Advantages of Composite Materials High Strength to Weight Ratio Light Weight Design Flexibility, to achieve desired stiffness, strength and manufacturing requirements Complex shapes are easily accomplished Fire Resistance Chemical and weathering Resistance Resistance to fatigue damage with good damping properties Low thermal conductivity
  • 20. 19 5. Disadvantages High Manufacturing Cost. A typical finished composite may cost in between 10-15 times (or even more) the cost of material being used. Synthetic fibers have low melting point and thus high temperature operation is not feasible for those type of composite Repairs of composites is very difficult and complicated, unlike metal based components Sometimes, critical flaws and cracks in the composite structure may go unnoticed 6. Conclusion A field of heave research and development Development of new types and obtaining the desired properties is the main focus Attempts are being made to reduce the manufacturing cost