# Rate-dependent yield

 Rate-dependent yield: is needed to define a material's yield behavior accurately when the yield strength depends on the rate of straining and the anticipated strain rates are significant; is available only for the isotropic hardening metal plasticity models (Mises, Johnson-Cook, and Hill), the isotropic component of the nonlinear isotropic/kinematic plasticity models, the extended Drucker-Prager plasticity model, and the crushable foam plasticity model; can be conveniently defined on the basis of work hardening parameters and field variables by providing tabular data for the isotropic hardening metal plasticity models, the isotropic component of the nonlinear isotropic/kinematic plasticity models, and the extended Drucker-Prager plasticity model; can be defined through specification of user-defined overstress power law parameters, yield stress ratios, or Johnson-Cook rate dependence parameters (this last option is not available for the crushable foam plasticity model and is the only option available for the Johnson-Cook plasticity model); cannot be used with any of the Abaqus/Standard creep models (metal creep, time-dependent volumetric swelling, Drucker-Prager creep, or cap creep) since creep behavior is already a rate-dependent mechanism; and in dynamic analysis should be specified such that the yield stress increases with increasing strain rate. The following topics are discussed:
 Related Topics Classical metal plasticity Models for metals subjected to cyclic loading Johnson-Cook plasticity Extended Drucker-Prager models Crushable foam plasticity models About the material library Inelastic behavior In Other Guides *RATE DEPENDENT Defining rate-dependent yield with yield stress ratios

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