A Brittle Damage Model: Implementation into LS-DYNA and Application to Normal Plate-on-Plate Impact

A brittle damage model developed by M. A. Grinfeld was implemented in the LS-DYNA finite element code and applied to the simulation of normal plate-on-plate impact. The model introduces a state variable measure of damage that evolves in proportion to the elastic strain energy. The model degrades the elastic shear modulus in proportion to the state variable’s current level. The implementation procedure by means of the LS-DYNA user- material interface is described. In a simulation of normal plate-on-plate impact, the model produced a gradient in elastic properties within the initially homogeneous target, and this gradient led to a partial reflection of the unloading wave. For a range of values for the material constants introduced by the damage model, the target’s free-surface velocity showed a gradual increase over time following the arrival of the initial compressive shock. This observation is discussed in light of the phenomenon of failure waves.