帮助文件中的解释.doc

帮助文件中的解释 11.2.7?Johnson-Cook plasticity Product: ABAQUS/Explicit?? The Johnson-Cook plasticity model is defined by using the *PLASTIC, HARDENING=JOHNSON COOK option and, optionally, the *RATE DEPENDENT, TYPE=JOHNSON COOK option. References *ANNEAL TEMPERATURE *PLASTIC *RATE DEPENDENT *SHEAR FAILURE *TENSILE FAILURE “Classical metal plasticity,” Section 11.2.1 “Rate-dependent yield,” Section 11.2.3 “Equation of state,” Section 10.9.1 “Failure models,” Section 11.2.8 “Annealing or melting,” Section 11.2.5 “Material library: overview,” Section 9.1.1 “Inelastic behavior,” Section 11.1.1 Overview The Johnson-Cook plasticity model: is a particular type of Mises plasticity model with analytical forms of the hardening law and rate dependence; is suitable for high-strain-rate deformation of many materials, including most metals; is typically used in adiabatic transient dynamic simulations; can be used in conjunction with the *SHEAR FAILURE, TYPE=JOHNSON COOK option to model shear failure; can be used in conjunction with the *TENSILE FAILURE option to model tensile spall or a pressure cutoff; and must be used in conjunction with either the linear elastic material model (“Linear elastic behavior,” Section 10.2.1) or the equation of state material model (“Equation of state,” Section 10.9.1). Yield surface and flow rule A Mises yield surface with associated flow is used in the Johnson-Cook plasticity model. Johnson-Cook hardening Johnson-Cook hardening is a particular type of isotropic hardening where the static yield stress, , is assumed to be of the form where is the equivalent plastic strain and , , and are material parameters measured at or below the transition temperature, . is the nondimensional temperature defined as where is the current temperature, is the melting temperature, and is the transition temperature defined as the one at or below which there is no temperature dependence on the expression of the yield stress. The material parameters must be measured