Eulerian finite element implementation of a dislocation density-based continuum model with application to simulations of drop weight impact test

In Eulerian finite element simulations, the mesh moves relative to the material. After every change of position between the mesh and the material, the state variables are interpolated to the new mesh position, i.e., advection. Large strain crystal plasticity models are based on a multiplicative decomposition of the total deformation gradient. The stress is evaluated as a function of the thermoelastic strain, temperature, and other state variables. Advection of tensor quantities, e.g., strain, is coupled with possibly significant advection errors. In an effort to reduce the advection errors, we develop a rate form of a dislocation density-based continuum model by Luscher et al. in Abaqus. To that end, we replace the multiplicative decomposition of the deformation gradient with the additive decomposition of velocity gradient, and define the stress rate instead of the total stress. In a drop weight impact test, a sample sitting on an anvil is compressed to large strain by a falling weight. We use the Eulerian implementation to simulate the deformation and temperature evolution in the sample. Results for single crystal and polycrystal cyclotrimethylene trinitramine samples will be presented.