Numerical Simulations of Tension Tests with a new Rate and Temperature Dependent Continuum Damage and Fracture Model

The new continuum damage model is based on a general thermodynamic framework for the modeling of rate and temperature dependent behavior of anisotropically damaged elastic-plastic materials subjected to fast deformation. The introduction of damaged and fictitious undamaged configurations allows the definition of damage tensors and the corresponding free energy functions leads to material laws effected by damage and temperature. A generalized hydrostatic-stress-dependent yield condition and a non-associated flow rule describe the plastic material behavior. The damage condition and the corresponding damage rule strongly depend on stress triaxiality. Furthermore the rate and temperature dependence is reflected in a multiplicative decomposition of the plastic hardening and damage softening function. The macro crack behavior is characterized by a triaxiality dependent fracture criteria. The continuum damage model is implemented into LS-DYNA as user defined material model. Corresponding numerical simulations of unnotched and notched tension tests with high strain rates demonstrate the plastic and damage processes during the deformation leading to final fracture which is numerically predicted by an element erosion technique.

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