《材料科学与工程基础》英文影印版习题及思考(17)

《材料科学与工程基础》英文习题及思考题及答案,本人从网上狂搜,兄弟们姐妹们狂下啊,不要辜负我的劳动啊!!!!

9.35 The fatigue data for a ductile cast iron are given

as follows:

(a) Make an S–N plot (stress amplitude

versus logarithm cycles to failure) using the

data.

(b) What is the fatigue limit for this alloy?

(c) Determine fatigue lifetimes at stress

amplitudes of 230 MPa and 175 MPa

(d) Estimate fatigue strengths at 2_105 and

6 _ 106 cycles.

9.36 Suppose that the fatigue data for the cast iron in Problem 9.35 were taken for

bending rotating tests, and that a rod of this alloy is to be used for an automobile axle that rotates at an average rotational velocity of 750 revolutions per minute. Give maximum lifetimes of continuous driving that are allowable for the

following stress levels: (a) 250 Mpa , (b) 215 MPa , (c) 200 MPa , and (d) 150 Mpa .

9.38 (a) Compare the fatigue limits for polystyrene (Figure 9.27) and the cast iron for

which fatigue data are given in Problem 9.35.

(b) Compare the fatigue strengths at 106 cycles for polyethylene terephthalate (PET, Figure 9.27) and red brass (Figure 9.46).

9.39 Cite five factors that may lead to scatter in fatigue life data.

12.6 What is the distinction between electronic and ionic conduction?

12.7 How does the electron structure of an isolated atom differ from that of a solid

material?

12.8 In terms of electron energy band structure, discuss reasons for the difference in

electrical conductivity between metals, semiconductors, and insulators.

12.9 If a metallic material is cooled through its melting temperature at an extremely

rapid rate, it will form a noncrystalline solid (i.e., a metallic glass). Will the electrical conductivity of the noncrystalline metal be greater or less than its crystalline counterpart? Why?

12.10 Briefly tell what is meant by the drift velocity and mobility of a free electron.

12.11 (a) Calculate the drift velocity of electrons in germanium at room temperature

and when the magnitude of the electric field is 1000 V/m.

(b) Under these circumstances, how long does it take an electron to traverse a 25