Question

A component under load alone is 100 Hrs while under normal load, it is 1000 hrs. How many hours it can be operated at normal load, if it is found to be operated for 10 hrs at heavy load?

• A. 800 Hrs
• B. 800 Hrs
• C. 700 Hrs
• D. 600 Hrs

Answer 1

The correct option is C 700 Hrs

${\sigma }_{max}=125MPa,{\sigma }_{min}=75MPa$

$S_e=75MPa,S_{yt}=200MPa$

$S_m=\frac{125+75}{2}=100MPa$

$S_a=\frac{125-75}{2}=25MPa$

According to Soderberg's equation

$\frac{S_m}{S_{yt}}+\frac{S_a}{S_e}=\frac{1}{FS}$

$\frac{100}{200}+\frac{25}{75}=\frac{1}{FS}$

$\Rightarrow F_s=1.2$