Dynamic fragmentation of brittle solids: a multi-scale model

Modeling dynamic fragmentation of brittle materials usually implies to choose between a discrete description of the number of fragments and a continuum approach with damage variables. A damage model that can be used in the whole range of loadings (from quasi-static to dynamic ones) is developed. The deterministic or probabilistic nature of fragmentation is discussed. Qualitative and quantitative validations are given by using a real-time visualization configuration for analyzing the degradation kinetics during impact and a moiré technique to measure the strains in a ceramic tile during impact. Finally, a closed-form solution of the change of the number of broken defects with the applied stress gives a way of optimizing the microstructure of ceramics for armor applications.