Stress analysis of structural material for the submarine gives the state of stress as shown in the figure. The yield strength of the material is 450 MPa. Using Tresca’s yielding criteria determine whether yielding will occur or not? If not, what is the factor of safety?

Correct Answer: Yielding will occur, and the factor of safety is 1.125
According to Tresca’s criteria τmax = (σ1– σ3)/2 should be greater than σo/2 for yielding to occur. => τmax = (σ1– σ3)/2 => τmax = (300-(-100))/2 = 200 MPa Shear stress in pure tension is σo/2 => 450/2 = 225 MPa Factor of safety = 225/200 = 1.125.