# Questions & Answers of Failure Theories

The principal stresses at a point inside a solid object are $\sigma_1=100\;\mathrm{MPa}$ $\sigma_2=100\;\mathrm{MPa}$ and $\sigma_3=0\;\mathrm{MPa}$. The yield strength of the material is 200 MPa. The factor of safety calculated using Tresca (maximum shear stress) theory is nT and the factor of safety calculated using von Mises (maximum distortional energy) theory is $n_V$. Which one of the following relations is TRUE?

Which one of the following is the most conservative fatigue failure criterion?