2. Introduction to Composite Materials (Laminated Composite Materials) Mechanical Engineering Instructor: Autar Kaw

3. High Gas Prices

4. 2007 Titus Racer X Exogrid

5. The Full Page Ad for 2007 Titus Racer X Exogrid

6. The Fine Print in the Full Page Ad

7. 2008 Titus Motolife

8. The fine print in the ad

9. My wish

10. What are you going to learn? What are composite materials? How are they manufactured? What advantages and drawbacks do composites have over metals? Develop mathematical models to understand the mechanical response of composites to mechanical and hygrothermal loads? Use the above mathematical models to optimally design structures made of composites.

11. What is a composite? A composite is a structural material which consists of combining two or more constituents Examples:  Flesh in your leg reinforced with bones  Concrete reinforced with steel  Epoxy reinforced with graphite fibers.

12. “You are no longer to supply the people with straw for making bricks; let them go and gather their own straw” - Exodus 5.7.

13. Shift in Paradigm About Materials “More important than any one new application is the new ‘materials’ concept itself ” Peter F. Drucker The Age of Discontinuity, 1969Age of Discontinuity

14. What is this paradigm shift in materials? From substance to structures From artisan to science From workshop to mathematical modeling From what nature provides to what man can accomplish

15. Are Composites Important? Considered as one of the ten outstanding achievements of 1964-1989

16. From constituents to application

17. Schematic of Analysis of Laminated Composites

18. Chapter 1 Introduction to Composite Materials

19. Short Videos on Composite Materials Some videos of composite materials NASA uses composite materials in shuttle Composites improve efficiency Cloth composites Dan Rather shows courage going after Boeing  Part 1 Part 1  Part 2 Part 2  Part 3 Part 3  Part 4 Part 4

20. What is a composite? What are the advantages and drawbacks of composites over monolithic materials? What factors influence mechanical properties of a composite Chapter 1: Objectives

21. How do we classify composites? What are the common types of fibers and matrices? How are composite materials manufactured? What are the mechanical properties of composite materials? Chapter Objectives (continued)

22. Give applications of composite materials. How are composites recycled? What terminology is used for studying mechanics of composites?

23. What is an advanced composite? Advanced composites are composite materials which were traditionally used in aerospace industries Examples include graphite/epoxy, Kevlar/epoxy and Boron/aluminum

24. Examples of Natural Composites Wood  Cellulose Fibers  Lignin Matrix Bones  Collagen Fibers  Mineral Matrix

25. Fibrous Composites Generally there are two phases  Fiber as a reinforcement  Matrix as a binder

26. Historical Perspective 4000 B.C. Fibrous composites were used in Egypt in making laminated writing materials 1300 BC: Reference to Book of Exodus 1700 AD: French Scientist, Reumer talked about potential of glass fibers

27. Historical Perspectives (continued) 1939: Glass fiber manufactured commercially for high temperature electrical applications 1950s: Boron and carbon fibers were produced to make ropes. 1960s: Matrix added to make polymeric matrix composites

28. Historical Perspectives (continued) 1970s: Cold war forces development of metal matrix composites for military aircrafts and missile guidance systems 1990s: High temperature ceramic matrix composites are being aggressively researched for use in next generation aircraft engines and power plant turbines

29. Shipments of Composites

30. World Market of Composites

31. Advantages of Composites Specific Strength and Stiffness Tailored Design Fatigue Life Dimensional Stability Corrosion Resistance Cost-Effective Fabrication

32. Drawbacks of Composites High cost of fabrication of composites Complex mechanical characterization Complicated repair of composite structures High combination of all required properties may not be available

33. Composites vs. Metals

34. Comparison based on six primary material selection parameters

35. Why composites over metals? High Strength and High Stiffness Tailored Design Fatigue Life Dimensional Stability Corrosion Resistance

36. Why Composites over Metals? How is the mechanical advantage of composite measured?

37. Specific Strength vs. Year

38. Table 1.1. Specific modulus and strength of typical fibers, composites and bulk metals

39. Specific Strength vs Specific Modulus

40. Other Mechanical Parameters Are specific modulus and specific strength the only mechanical parameters used for measuring the relative advantage of composites over metals? NO!!

41. Tailored Design Engineered to meet specific demands as choices of making the material are many more as compared to metals. Examples of choices  fiber volume fraction  layer orientation  type of layer  layer stacking sequence

42. Fatigue Life Fatigue life is higher than metals such as aluminum. Important consideration in applications such as  aircrafts  bridges  structures exposed to wind

43. Dimensional Stability Temperature changes can result  in overheating of components (example engines)  thermal fatigue due to cyclic temperature changes (space structures)  render structures inoperable (space antennas)

44. Corrosion Resistance Polymers and ceramics matrix are corrosion resistant Examples include  underground storage tanks  doors  window frames  structural members of offshore drilling platforms

45. What is most limiting factor in the use of composites in structures? Lack of engineers with the knowledge and experience to design with these materials!!!!

46. Cost Considerations Composites may be more expensive per pound than conventional materials. Then why do we use composite materials?

47. Factors in Cost Estimate For Composite Materials  Fewer pounds are required  Fabrication cost may be lower  Transportation costs are generally lower  Less maintenance than conventional materials is required

48. Fiber Factors What fiber factors contribute to the mechanical performance of a composite? Length Orientation Shape Material

49. Fiber Factor - Length Long Fibers  Easy to orient  Easy to process  Higher impact resistance  Dimensional stability Short Fibers  Low Cost  Fast cycle time

50. Fiber Factor - Orientation One direction orientation  High stiffness and strength in that direction  Low stiffness and strength in other directions Multi-direction orientation  Less stiffness but more direction independent

51. Fiber Factor - Shape Most common shape is circular Hexagon and square shapes give high packing factors

52. Fiber Factor - Material Graphite and aramids have high strength and stiffness Glass has low stiffness but cost less

53. Matrix Factors What are the matrix factors which contribute to the mechanical performance of composites?  Binds fibers together  Protects fibers from environment  Shielding from damage due to handling  Distributing the load to fibers.

54. Factors Other Than Fiber and Matrix Fiber-matrix interface  Chemical bonding  Mechanical bonding

55. Fiber Types Glass Fiber (first synthetic fiber) Boron (first advanced fiber) Carbon Silicon Carbide

56. Types of Matrices Polymers Metals Ceramics

57. Polymer Matrix Thermosets  polyester  epoxy  polymide Thermoplastics  polypropylene  polyvinyl chloride  nylon

58. Metal Matrix Aluminum Titanium Copper

59. Ceramic Matrix Carbon Silicon Carbide Calcium AluminoSilicate Lithium AluminoSilicate

60. Why do fibers have thin diameter? Less flaws More toughness and ductility Higher flexibility Thin Fiber Thick Fiber

61. Less Flaws

62. More Toughness and Ductility Fiber-matrix interface area is inversely proportional to the diameter of the fibers Higher surface area of fiber-matrix interface results in higher ductility and toughness, and better transfer of loads.

63. More Flexibility Flexibility is proportional to inverse of Young’s modulus Fourth power of diameter Thinner fibers hence have a higher flexibility and are easy to handle in manufacturing.

64. Polymer Matrix Composites What are the most common advanced composites?  Graphite/Epoxy  Kevlar/Epoxy  Boron/Epoxy

65. Polymer Matrix Composites What are the drawbacks of polymer matrix composites?  Low operating temperatures  High CTE and CMEs  Low elastic properties in certian directions

66. Are Carbon and Graphite the Same? No  Carbon fibers have 93%-95% carbon content and graphite has >99% carbon content  Carbon fibers are produced at 2400 o F and graphite fibers are produced at 3400 o F

67. Table 1.4. Typical mechanical properties of polymer matrix composites and monolithic materials

68. Comparative Stiffness of PMCs and Metals

69. How to make a PMC

70. Prepreg Boron/Epoxy

71. Autoclave Lamination

72. Filament Winding Filament Winding Video

73. Resin Transfer Molding

74. Common PMC Fibers & Matrices Fibers  Graphite  Glass  Kevlar Matrices  Epoxy  Phenolic  Polyester

75. Table 1.5 Typical mechanical properties of fibers used in polymer matrix composites

76. Cost Comparison of PMC fibers Type of fiberCost ($ per pound) A-glass0.65 -.90 C-glass0.75 - 1.00 E-glass0.75 - 1.00 S-2 Glass6.00 - 8.00 Heavy Tow9.00 - 12.00 Medium Tow15.00 -20.00 Low Tow40.00 -70.00+ Kev2912.00 -14.00 Kev14925.00 -30.00

77. Manufacturing of Glass Fibers

78. Glass Fiber Types E-glass (fiberglass) - electrical applications S-glass - strength applications C-glass - Corrosion resistant D-glass - Low dielectric applications A-glass - Appearance applications AR-glass - Alkali resistant

79. Table 1.6 Comparison of properties of E-glass and S-glass

80. Table 1.7 Chemical Composition of E-Glass and S-Glass Fibers

81. Fig 1.10 Forms of Fibers

82. Fig 1.11 Manufacturing Graphite Fibers

83. Resin Systems Polyester Phenolics Epoxy Silicone Polymide

84. Properties of epoxy

85. Curing Stages of Epoxy

86. Comparison of Resins

87. Difference between thermosets and thermoplastics

88. Pre-Preg Graphite/Epoxy

89. Application of Polymer Matrix Composites A strong, ultra light leg prosthesis of graphite/epoxy help athletes compete at the highest levels.

90. Space Shuttle

91. Every body skiing USA SMC: sheet molded compound FRC : Fiberglass Reinforced composite.

92. Lear Fan

93. Fighter Jets

94. Corvette Leaf Springs

95. Snow Skis

96. I-beam

97. Pressure vessels

98. Composites changed the game of tennis

99. Moon probe Build the camera so that it was out of focus on Earth. The carbon fiber telescope can be baked to drive the water out. This causes the structure to shrink and bring the instrument into focus. CRaTER - will characterize the global lunar radiation environment Diviner - is to measure lunar surface temperatures LAMP - will map the Moon's permanently shadowed regions LEND - measures the flux of neutrons from the Moon LOLA - will provide a global lunar topographic model LROC - LRO's camera will help select future landing sites Mini-RF - uses radar to search for evidence of water ice

100. Metal Matrix Composites What are metal-matrix composites? Metal matrix composites have a metal matrix. Examples include silicon carbide fibers in aluminum, graphite fibers in aluminum.

101. Advantages of MMCs Higher specific strength and modulus over metals. Lower coefficients of thermal expansion than metals by reinforcing with graphite. Maintenance of high strength properties at high temperatures.

102. Degrading properties in MMCs Are there any properties which degrade when metals are reinforced with fibers? Yes, they may have reduced ductility and fracture toughness.

103. Typical mechanical properties of metal matrix composites

104. Boron Fiber

105. Step 0: Cutting the shape

106. Step 1: Apply Aluminum File

107. Step 3: Lay Up Desired Plies

108. Step 4:Vacuum the specimen

109. Step5: Heat to Fabrication Temperature

110. Step 6: Apply Pressure and Hold for Consolidation Cycle

111. Step 7: Cool, Remove and Clean Part

112. Schematic of Diffusion Bonding

113. Silicon Carbide/ Aluminum Composite

114. Application of MMCs

117. Ceramic Matrix Composites What are ceramic matrix composites? Ceramic matrix composites have matrices of alumina, calcium alumino silicate (CAS), lithium alumino silicate (LAS). Examples include Silicon Carbide/CAS and Carbon/LAS.

118. Advantages of CMCs High strength, hardness and high service temperatures Chemical inertness Low Density

119. Table 1.12 Typical fracture toughness of monolithic materials and ceramic matrix composites

120. Table 1.13 Typical mechanical properties of some ceramic matrix composites

121. Manufacturing of Ceramic Matrix Composites - Slurry Infiltration

122. Application of CMCs

123. Carbon-Carbon Compoistes What are carbon-carbon composites? Carbon - Carbon composites have carbon fibers in carbon matrix.

124. Advantages of Carbon-Carbon Composites Gradual failure Withstand high temperatures Low creep at high temperatures Low density High thermal conductivity Low and tailorable Coefficient of Thermal Expansion

125. Advantages of Carbon-Carbon Composites Great strength to weight ratio High modulus, thermal conductivity, and electrical conductivity Good thermal shock resistance, abrasion resistance, and fracture toughness Excellent high temperature durability in inert or vacuum environment Good corrosion resistance

126. Table 1.14 Typical mechanical properties of carbon-carbon matrix composites

127. Carbon-Carbon Manufacturing

128. Applications of C-C Composites Space Shuttle Nose Cones  Re-entry temperature of 3092 K Aircraft Brakes  Saves 450 kgs of mass  Two-four times durability vs. steel  2.5 times specific heat of steel

129. Recycling of Composites What types of process are used for recycling of composites? Why is recycling of composites complex? What can one do if one cannot separate different types of composites?

130. Recycling Continued What are the various steps in mechanical recycling of short fiber-reinforced composites? Where are mechanically recycled short fiber composites used?

131. Chemical Recycling Why is chemical recycling not as popular as mechanical recycling? Which chemical process shows the most promise?

132. Definitions Isotropic body Homogeneous body Anisotropic body Nonhomogeneous body Lamina Laminate

133. Schematic of Analysis of Laminated Composites

134. An Artist’s Rendition of a Composite Material