Working stress and Factor for Safety Working Stress:

Working stress is safe stress taken within elastic range of material. For the brittle materials, it is taken equal to ultimate strength divided by appropriate factor of safety. However, for the materials possessing defined yield point, it is equal to yield stress divided by factor of safety. It is stress which accounts all the types of uncertainties.

     Working stress = Ultimate strength/ Factors of safety  for brittle materials

                           =  Yield strength / Factors of safety   for ductile materials

It is called as permissible stress, allowable stress, actual stress and safe stress.