Model of fragmentation distribution over a protective wall

This paper presents an analysis of perforated witness plates that were part of an experimental setup of previously published field tests. The witness plates were placed in the field tests to check the fragmentation pattern of the cased charge. A qualitative inspection of the plates shows that the spatial mass distribution of the fragments was not uniform over the wall height, and that it was characterized by an intense strip, which was stricken by a high magnitude of the fragmentation mass. Image analysis of the post-test plate pictures indicated that a previously suggested model for the intense strip geometry and fragmentation mass ratio under-predicts these parameters for increased standoff distances. Consequently, the paper presents an updated, enhanced version of the model, which considers the variation of the fragmentation Taylor angle along the charge and leads to a thicker intense strip. The updated model parameters were chosen in accordance with the analyzed experimental results and they were further verified with image analyses from additional published experimental data. The enhanced intense-strip model presented here can be used for global consideration of the fragmentation loading over a wall they strike. Furthermore, it should be emphasized that contrary to the common design approach, which assumes uniform damage and/or loading of the fragments, this model provides a useful tool for a realistic evaluation of the structural response of a protective wall, which is subjected to the combined loading of blast and fragments.