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1、复合材料复习题库9.The transverse tensile strength of an aligned continuous fibre composite (A) is obtained when testing normal to(垂直于) the fibre axis, (B) is obtained when testing parallel to（平行于） the fibre axis, (C) is the lowest tensile stength, (D) is the highest tensile strength, (E)depends mainly on th
2、e properties of the matrix and of the fibre- matrix interface, (G) depends mainly on the properties of the fibres.Each of the sentences in questions 11 to 14 consists of an assertion followed by a reason. Answer: (A) if both assertion and reason are true statements and the reason is a correct explan
3、ation of the assertion, (B) if both assertion and reason are true statements but the reason is not a true explanation of the assertion, (C) if the assertion is true but the reason is a false statement, (D) if the assertion is false but the reason is a true statement, (E)if both the assertion and rea
4、son are false statements.11. The coefficient of thermal expansion of an MMC with a ceramic reinforcement is less than that of the matrix because the coefficient of thermal expansion of a ceramic is usually less than that of a metal. 12. Generally reinforcing a metal degrades both ductility and tough
5、ness because there is an increase in Youngs modulus. 13. Unfortunately reinforcement of a metal markedly reduces the fatigue resistance because cracks are readily formed within the reinforcement. 14. The specific strength and modulus of a silicon carbide particle(碳化硅 粒子) reinforced aluminium alloy a
6、re superior to those of the matrix because silicon carbide is more dense than the common aluminium alloys. 9. A,C,E; 11. A; 12. B; 13. E; 14. B; 9.Reinforcing alumina with SiC whiskers ABE (A) enhances the thermal shock resistance, (B) lowers the coefficient of thermal expansion, (C) decreases the t
7、hermal conductivity, (D) increases the density (E)improves the toughness.10.The room temperature tensile stress-strain curves in Figure 4.35 are for LAS-SiC fibre composites. The break-down of linearity in the curves at the point marked M is due to C （A）plastic deformation associated with dislocatio
8、n motion, (B)fracture of the fibres, (C)matrix microcracking, (D)viscous flow of a glassy phase, (E)fibre pull-out.11.Chemical vapour deposition of a carbon matrix BE (A) is also commonly known as gas carbonization, (B) is also commonly known as chemical vapour infiltration, (C) produces a brittle c
9、omposite with a glassy matrix, (D) is independent of deposition pressure, (E)is dependent on deposition temperature. 9.ABE;10.C;11.BEIndicate whether statements 1 to 7 are true or false. 1.Polyester(聚酯) and epoxy（环氧） are examples of thermosets(A) true (B) false2.Phenolic resins known as resoles or o
10、ne-stage resins require the addition of a curing agent prior to fabrication. (A) true (B) false3.Polycarbonate （聚碳酸酯） is an accepted generic term for synthetic polyamides（聚酰胺）(A) true (B) false4.Hand lay-up （手糊成型）requires little capital equipment but is labour intensive(A) true (B) false5.Figure 5.2
11、4 is a diagram of matched-die moulding（对模成型）(A) true (B) false6.It has been estimated that over three-quarters of all matrices of PMCs are thermosets and of these the majority is polyester. (A) true (B) false7.Although many benefits accrue from reinforcing PEEK（聚醚醚铜） , unfortunately the creep proper
12、ties are significantly degraded with the result that PEEK matrix composites cannot be used at temperatures in excess of 40 .(A) true (B) falseFor each of the statements of questions 8 to 14, one or more of the completions given are correct. Mark the correct completions.8.Thermosetting polymers (A) a
13、re also known as thermoplastic polymers, (B) are also known as rubbers, (C) readily cross-link during curing, (D) cannot be cured, (E) cannot be reheated and reshaped9. Thermoplastics (A) are cross-linked polymers, (B) are linear polymers, (C) may have branched chains, (D) readily flow at elevated t
14、emperatures,(E) cannot be reheated and shapedI0.Polyetheretherketone(聚醚醚铜) (A) is also known as PEEK, (B) is a type of nylon, (C) is a thermoplastic, (D) is a semi-crystalline polymer, (E) has a high glass-transition temperature of 143 11 Spray-up (A) is faster than hand lay-up, (B) involves sprayin
15、g a non-viscous resin at a preform, (C) involves spraying chopped fibres and resin on to a mould, (D) composites have to be rolled to give a smooth surface finish, (E) composites have to be rolled to remove entrapped air, (F)composites have to be vacuum degassed to remove entrapped air12.Pultrusion
16、(A) is a slow labour intensive production method, (B) is particularly suited to the production of large, complex, planar shapes, (C) is used for the production of rods of uniform cross-section, (D) involves pushing fibres into a closed mould containing resin, (E) involves pulling resin impregnated fibres through a heated die.13.The mechanical properties of glass-reinforced epoxies are affected by moisture because(A) the epoxy matrix becomes mor
