This paper presents a dynamic damage model for predicting fracture and fragmentation of brittle materials subjected to loads with high loading rates. This model is based on the mechanics of microcrack nucleation, growth, and coalescence to formulate the evolution of damage. The damage in the model is assumed to be isotropic and is a function of time and applied stress. The model provides a direct, explicit, and quantitative method to determine the rate-dependent fracture stress and fragment size generated by crack coalescence in the dynamic fragmentation process. It considers the experimental facts that a brittle material does not fail if the applied stress is lower than its static strength and certain time duration is needed for fracture to take place when it is subjected to a stress higher than its static strength. Comparisons between theoretical predictions and test data are made and shown to be in good agreement.
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