1.(单选题)空心圆轴的内径为d,外径为D,其内径和外径的比为d/D=α,写出横截面的极惯性矩和抗扭截面系数的正确表达式应当是()

A.0.8

B.0.6

C.0.5

D.0（实心轴）

A.πd²/4

B.πd⁴/32

C.πd³/16

D.πd⁴/64

A.空心钢轴的较大

B.实心铝轴的较大

C.其值一样大

D.其大小与轴的变模量有关

A.$\frac{\pi}{16}(D^4-d^4)$

B.$\frac{\pi}{16}\frac{(D^4-d^4)}{D}$

C.$\frac{\pi}{32}\frac{(D^4-d^4)}{D}$

D.$\frac{\pi}{16}\frac{(D^2-d^2)}{D}$

A.16t

B.8t

C.4t

D.2t

A.Z=π/64*(D^4-d^4)/d

B.Z=π/32*(D^3-d^3)/d

C.Z=π/8*(D^4-d^3)/D

D.Z=π/32*(D^4-d^4)/D

A.不变

B.增加一倍

C.减少一半

D.增加四倍

A.2倍

B.4倍

C.8倍

D.16倍

A.2倍

B.4倍

C.8倍

D.16倍