Publications Details

Dynamic failure of materials using the material point method in CTH

Schumacher, Shane C.; Ruggirello, Kevin P.

The dynamic failure of materials in a finite volume shock physics computational code poses many challenges. Sandia National Laboratories has added Lagrangian markers as a new capability to CTH. The failure process of a marker in CTH is driven by the nature of Lagrangian numerical methods. This process is performed in three steps and the first step is to detect failure using the material constitutive model. The constitutive model detects failure computing damage or other means from the strain rate, strain, stress, etc. Once failure has been determined the material stress and energy states are released along a path driven by the constitutive model. Once the magnitude of the stress reaches a critical value, the material is switched to another material that behaves hydrodynamically. The hydrodynamic failed material is by definition non-shear-supporting but still retains the Equation of State (EOS) portion of the constitutive model. The material switching process is conservative in mass, momentum and energy. The failed marker material is allowed to fail using the CTH method of void insertion as necessary during the computation.