Homework

Chapter $6$

For a polished rotating beam test specimen in pure completely reversed bending made of $4130$ alloy steel with $S_{ut}=100k,$ estimate:

Given:

$k_a=0\mathrm{.}963,k_b=1,k_c=0\mathrm{.}85,k_d=1,k_e=0\mathrm{.}814,$ and $k_f=1$

a$)$ The rotating$-$beam endurance limit$,S_e,$ at ${10}^6.$

b$)$ The fatigue strength of a polished rotating beam specimen corresponding to ${10}^5$ cycles to failure.

c$)$ The expected life of a polished rotating$-$beam specimen under a completely reversed stress of $68$ kpsi $.$

d$)$ At a completely reversed stress of $29$ kpsi $,$ the specimen has infinite life. True or false and why?

e$)$ The fatigue strength of a polished rotating beam specimen corresponding to $800$ cycles to failure.