Description: The damage evolution response describes the rate of degradation of the material stiffness once the corresponding initiation criterion has been reached. A typical stress-strain response of an elastic-plastic material undergoing damage is depicted in Figure 7–1.

Abaqus offers two types of damage evolution models:

• Models based on effective plastic displacement with linear, tabular, and exponential softening.

• Models based on energy dissipated during the damage process with linear and exponential softening.

These models can be used in conjunction with the ductile, shear, FLD, FLSD, and MSFLD initiation criteria. Furthermore, Abaqus provides controls associated with element deletion due to material failure. All the models use a formulation intended to alleviate the mesh dependence of the results that can arise due to strain localization during progressive damage. In addition, a viscous regularization technique can be used to improve convergence difficulties, which typically occur in implicit analysis programs—such as Abaqus/Standard—when modeling materials exhibiting softening behavior. The damage evolution models are suitable for both quasi-static and dynamic problems.

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