Nonlinear analysis formulation > Inelastic stress-strain behavior > Hardening rule

Hardening rule predicts the change in the yield surface due to plastic strains. Two hardening rules can be formulated:

• Isotropic hardening: Bauschinger effect is ignored but the elastic range expands.
• Kinematic hardening: Bauschniger effect is included but elastic range remains constant. Isotropic hardening can be represented by the plastic work per unit volume Wp thus:

		(140)

Kinematic hardening is given by vector determining the translation of the yield surface in general stress state.

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