Crack softening damage model for ceramic impact and its application within a hydrocode

A physically based crack softening damage model has been developed and used in a non-linear transient dynamic computer code (AUTODYN-2D). It is assumed that there is a finite number of orientated pre-existing flaws within the ceramic target. The mode I and mode II stress intensity factors are calculated in compression and tension and the strain energy release rate is then estimated and compared to a critical dynamic strain energy release rate. At initiation, a tension crack propagates at a velocity dependent on the mode I stress intensity factor and failure occurs in a computational cell when two neighbouring microcracks coalesce. The model was used to simulate two different plate impact experiments of alumina on alumina with encouraging results. The model was also used to analyze the impact of a steel sphere on alumina and shows strong correlation between experimental and predicted results.