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Textile Structural Composites

Textile Structural Composites

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Textile Structural Composites

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  1. Textile Structural Composites Yiping Qiu College of Textiles Donghua University Spring, 2006

  2. Reading Assignment • Textbook chapter 1 General Information. • High-Performance Composites: An Overview, High-PerformanceComposites, 7-19, 2003 Sourcebook. • FRP Materials, Manufacturing Methods and Markets, Composites Technology, Vol. 6(3) 6-20, 2000.

  3. Expectations • At the conclusion of this section, you should be able to: • Describe the advantages and disadvantages of fiber reinforced composite materials vs. other materials • Describe the major applications of fiber reinforced composites • Classification of composites

  4. Introduction • What is a composite material? • Two or more phases with different properties • Why composite materials? • Synergy • History • Current Status

  5. Introduction • Applications • Automotive • Marine • Civil engineering • Space, aircraft and military • Sports

  6. Applications in plane

  7. Fiber reinforced composite materials • Classifications according to: • Matrices • Polymer • Thermoplastic • Thermoset • Metal • Ceramic • Others

  8. Fiber reinforced composite materials • Classifications • Fibers • Length • short fiber reinforced • continuous fiber reinforced • Composition • Single fiber type • Hybrid • Mechanical properties • Conventional • Flexible

  9. Fiber reinforced composite materials • Advantages • High strength to weight ratio • High stiffness to weight ratio • High fatigue resistance • No catastrophic failure • Low thermal expansion in fiber oriented directions • Resistance to chemicals and environmental factors

  10. Comparison of specific gravities 8 6 Specific gravity (g/cc) 4 2 0 Steel Al alloy Ti alloy Kevlar/epoxy Carbon/epoxy materials

  11. Fiber reinforced composite materials • Disadvantages • Good properties in one direction and poor properties in other directions. • High cost due to expensive material and complicated fabrication processes. • Some are brittle, such as carbon fiber reinforced composites. • Not enough data for safety criteria.

  12. Design of Composite Materials • Property Maps • Merit index

  13. Design of Composite Materials • Merit index • Example for tensile stiffness of a beam • However, for a given tensile sample, tensile stiffness has nothing to do with length or L = 1 may be assumed

  14. Design of Composite Materials • How about for torsion beams and bending plates? Lets make the derivation of these our first homework.

  15. Major components for fiber-reinforced composites • Reading assignment: • Textbook Chapter 2 Fibers and matrices • Fibers • Share major portion of the load • Matrix • To transfer stress between the fibers • To provide a barrier against an adverse environment • To protect the surface of the fibers from mechanical abrasion

  16. Major components for fiber reinforced composites • Coupling agents and coatings • to improve the adhesion between the fiber and the matrix • to protect fiber from being reacted with the matrix or other environmental conditions such as water moisture and reactive fluids. • Fillers and other additives: • to reduce the cost, • to increase stiffness, • to reduce shrinkage, • to control viscosity, • to produce smoother surface.

  17. Materials for fiber reinforced composites Mainly two components: • Fibers • Matrices

  18. Materials for fiber reinforced composites • Fibers • Influences: • Specific gravity, • Tensile and compressive strength and modulus, • Fatigue properties, • Electrical and thermal properties, • Cost.

  19. Materials for fiber reinforced composites • Fibers • Fibers used in composites • Polymeric fibers such as • PE (Spectra 900, 1000) • PPTA: Poly(para-phenylene terephthalamide) (Kevlar 29, 49, 149, 981, Twaron) • Polyester (Vectran or Vectra) • PBZT: Poly(p-phenylene benzobisthiozol)

  20. Materials for fiber reinforced composites • Fibers • Inorganic fibers: • Glass fibers: S-glass and E-glass • Carbon or graphite fibers: from PAN and Pitch • Ceramic fibers: Boron, SiC, Al2O3 • Metal fibers: steel, alloys of W, Ti, Ni, Mo etc. (high melting temperature metal fibers)

  21. Materials for fiber reinforced composites • Most frequently used fibers • Glass • Carbon/graphite • PPTA (Kevlar, etc.) • Polyethylene (Spectra) • Polyester (Vectra)

  22. Materials for fiber reinforced composites • Carbon fibers • Manufacturing processes • Structure and properties

  23. Materials for fiber reinforced composites • Carbon fibers • Manufacturing processes • Thermal decomposition of fibrous organic precursors: • PAN and Rayon • Extrusion of pitch fibers

  24. Materials for fiber reinforced composites • Carbon fiber manufacturing processes • Thermal decomposition of fibrous organic precursors • Rayon fibers • Rayon based carbon fibers • Stabilization at 400°C in O2, depolymerization & aromatization • Carbonization at 400-700°C in an inert atmosphere • Stretch and graphitization at 700-2800°C (improve orientation and increase crystallinity by 30-50%)

  25. Materials for fiber reinforced composites • Carbon fiber manufacturing processes • Thermal decomposition of fibrous organic precursors • PAN (polyarylonitrile) based carbon fibers • PAN fibers (CH2-CH(CN)) • Stabilization at 200-300°C in O2, depolymerization & aromatization, converting thermoplastic PAN to a nonplastic cyclic or ladder compound (CN groups combined and CH2 groups oxidized) • Carbonization at 1000-1500°C in an inert atmosphere to get rid of noncarbon elements (O and N) but the molecular orientation is still poor. • Stretch and graphitization at >1800°C, formation of turbostratic structure

  26. Materials for fiber reinforced composites • Pitch based carbon fibers • pitch - high molecular weight byproduct of distillation of petroleum • heated >350°C, condensation reaction, formation of mesophase (LC) • melt spinning into pitch fibers • conversion into graphite fibers at ~2000°C

  27. Materials for fiber reinforced composites • Carbon fibers • Advantages • High strength • Higher modulus • Nonreactive • Resistance to corrosion • High heat resistance • high tensile strength at elevated temperature • Low density

  28. Materials for fiber reinforced composites • Carbon fibers • Disadvantages • High cost • Brittle

  29. Materials for fiber reinforced composites • Carbon fibers • Other interesting properties • Lubricating properties • Electrical conductivity • Thermal conductivity • Low to negative thermal expansion coefficient

  30. Materials for fiber reinforced composites • Carbon fibers • heat treatment below 1700°C • less crystalline • and lower modulus (<365 GPa) • Graphite fibers • heat treatment above 1700°C • More crystalline (~80%) and • higher modulus (>365GPa)

  31. Materials for fiber reinforced composites • Glass fibers • Compositions and properties • Advantages and disadvantages

  32. Materials for fiber reinforced composites • Glass fibers • Compositions and Structures • Mainly SiO2 +oxides of Ca, B, Na, Fe, Al • Highly cross-linked polymer • Noncrystaline • No orientation • Si and O form tetrahedra with Si centered and O at the corners forming a rigid network • Addition of Ca, Na, & K with low valency breaks up the network by forming ionic bonds with O   strength and modulus

  33. Microscopic view of glass fiber Cross polar First order red plate

  34. Materials for fiber reinforced composites • Glass fibers • Types and Properties • E-glass (for electric) • draws well • good strength & stiffness • good electrical and weathering properties

  35. Materials for fiber reinforced composites • Glass fibers • Types and Properties • C-glass (for corrosion) • good resistance to corrosion • low strength

  36. Materials for fiber reinforced composites • Glass fibers • Types and Properties • S-glass (for strength) • high strength & modulus • high temperature resistance • more expensive than E

  37. Materials for fiber reinforced composites • Properties of Glass fibers

  38. Materials for fiber reinforced composites • Glass fibers • Production • Melt spinning

  39. Materials for fiber reinforced composites • Glass fibers • sizing: • purposes • protest surface • bond fibers together • anti-static • improve interfacial bonding • Necessary constituents • a film-forming polymer to provide protecting • e.g. polyvinyl acetate • a lubricant • a coupling agent: e.g. organosilane

  40. Materials for fiber reinforced composites • Glass fibers • Advantages • high strength • same strength and modulus in transverse direction as in longitudinal direction • low cost

  41. Materials for fiber reinforced composites • Glass fibers • disadvantages • relatively low modulus • high specific density (2.62 g/cc) • moisture sensitive

  42. Materials for fiber reinforced composites • Kevlar fibers • Structure • Polyamide with benzene rings between amide groups • Liquid crystalline • Planar array and pleated system

  43. Materials for fiber reinforced composites • Kevlar fibers • Types • Kevlar 29, E = 50 GPa • Kevlar 49, E = 125 GPa • Kevlar 149, E = 185 GPa

  44. Materials for fiber reinforced composites • Kevlar fibers • Advantages • high strength & modulus • low specific density (1.47g/cc) • relatively high temperature resistance

  45. Materials for fiber reinforced composites • Kevlar fibers • Disadvantages • Easy to fibrillate • poor transverse properties • susceptible to abrasion

  46. Materials for fiber reinforced composites • Spectra fibers • Structure: (CH2CH2)n • Linear polymer - easy to pack • No reactive groups • Advantages • high strength and modulus • low specific gravity • excellent resistance to chemicals • nontoxic for biomedical applications

  47. Materials for fiber reinforced composites • Spectra fibers • Disadvantages • poor adhesion to matrix • high creep • low melting temperature

  48. Materials for fiber reinforced composites • Other fibers • SiC and Boron • Production • Chemical Vapor Deposition (CVD) • Monofilament • Carbon or Tungsten core heated by passing an electrical current • Gaseous carbon containing silane