PPT Slide
The failure strength is either the yield strength ?o, or the ultimate strength ?u, depending on whether yielding or fracture is of interest.
Let us define an effective stress, ?, which is a single numerical value that characterizes the state of applied stress. If
where ?c is a known material property
Failure is not expected if
The safety factor against failure is given as:
That is the applied stress can be increased by a factor of X before failure occurs.