SUMMARY

There are very few commercially available software packages that will perform mechanical simulations due to shock wave propagation due to the need to have unfixed boundary conditions. In many finite element software packages, the inertia of the system is not considered, thus the object will be subject to infinite strain if subjected to impact loading. The explicit solver in LS-DYNA was chosen as a platform to test the effects of induces dynamic fracture or spall due to impact loading from a flyer-plate experimental setup. The motivating factor in the setup comes from the analysis of the source of spall. In all previous spall models, the source of failure either comes from damage at the grain boundary or from void nucleation, growth, and coalescence. However, it has been observed in experiments, that both phenomena occur. Thus, the challenge is then to determine the role that each source of spall plays separately, and in tandem to determine if it is the case that traditional failure parameters for each source are representative to that source’s role in data gathered from experiments.

Sand is a heterogeneous granular material that has the capability of allowing a shock wave to propagate through it. The computational model and study is phenomenologically similar, yet easier to conduct than the spall study on granular Aluminum. The study of sand using the same computational LS-DYNA method shows both an introduction to the process for completing the spall study on granular Aluminum, and it also yields nice results in the wave phenomena as well as the effect of porosity on the average stress on sand grains.