0- Any increase of stress introduces deformations in the material which is recoverable to a point called elastic limit. Further increase in stress introduces permanent deformations called plastic deformations. Yield criterion is a criterion defining the conditions for elastic limit. We have 2 experimental observations that hydrostatic stress does not cause yield and choice of axes does not alter yield criterion. So it is deviatoric stress responsible for yielding.
- 2 prominent criterion is there .1 st of Von Mises is based on the limit of distortion energy in a body and 2nd of Tresca is based on maximum shear stress limit.
