材料科学与工程专业英语12-unit16-17

1、材料科学与工程专业英语Special English for Materials Science and EngineeringUnit16 Introduction to CompositesUnit 17 Properties of composite mateiralsCompositesCombine materials with the objective ofgetting a more desirable combination ofpropertiesA composite materials is commonly defined as a combination of tw

2、o or more distinct materials that cannot be achieved by any of the components acting alone. Reinforced concrete:钢筋混凝土 Fiberglass:纤维玻璃 Resin：树脂WordsQuestions What is the composite? Can you give some examples? Which two phases do the composite materials have? Graphite：石墨 Kevlar：凯夫拉尔，纤维B（一种质地牢固重量轻的合成纤维

3、）；杜邦公司使用在芳族聚酰胺纤维商品上的注册商标 Epoxy resin：环氧树脂Words Composites: - Multiphase material with significant proportions of each phase. Dispersed phase: - Purpose: enhance matrix properties. MMC: increase sy, TS, creep resist. CMC: increase Kc PMC: increase E, sy, TS, creep resist. - Classification: Particle,

4、fiber, structural Matrix: - The continuous phase - Purpose is to: - transfer stress to other phases - protect phases from environment - Classification: MMC, CMC, PMCmetalceramicpolymerReprinted with permission fromD. Hull and T.W. Clyne, An Introduction to Composite Materials, 2nd ed., Cambridge Uni

5、versity Press, New York, 1996, Fig. 3.6, p. 47.Terminology/Classificationwoven fiberscross section view0.5mm0.5mmComposite Survey: Fiber Fibers themselves are very strong Provide significant strength improvement to material Ex: fiber-glass Continuous glass filaments in a polymer matrix Strength due

6、to fibers Polymer simply holds them in place and environmentally protects themParticle-reinforcedFiber-reinforcedStructuralComposite Survey: Fiber Fiber Materials Whiskers - Thin single crystals - large length to diameter ratio graphite, SiN, SiC high crystal perfection extremely strong, strongest k

7、nown very expensiveParticle-reinforcedFiber-reinforcedStructural Fibers polycrystalline or amorphous generally polymers or ceramics Ex: Al2O3 , Aramid, E-glass, Boron, UHMWPE Wires Metal steel, Mo, WFiber Alignmentalignedcontinuousaligned randomdiscontinuousAdapted from Fig. 16.8, Callister 7e. Unit

8、 17 Properties of composite materials Isotropic:各向同性的 Orthotropic：正交各向异性的 Moment：力矩 Thermoset：热固体 Thermoplastic：热塑体 Orientation：取向 Poissons ratio：泊松比 WordsMechanics of composite materialsQuestion What is the difference between isotropic materials and orthotropic materialsFailure of composites Delamination: 脱层 buckling 压曲；压弯 Net section:净截面WordsQuestion What is the difference between isotropic materials and orthotropic materialsAdvantage of composite materials Why use composites? Strength,