Nonlinear analysis formulation > Inelastic stress-strain behavior > Yield criterion

Yield criterion or yield function, defines the state of stresses at which material response changes from elastic to plastic. We define a yield function F, which is a function of stresses σ and quantities α and Wp which control the hardening (i.e. how a given yield surface in space is modified due to a plastic strain response:

		(137)

If we evaluate F the possible results are:

Fig. 38. Yield surface.

© GeoStru Software