Predicting dynamic failure of dense granules from static compression tests

This paper shows how static failure loads can be used to predict impact failure of granules. A theoretical model is presented that gives the maximum force experienced during impact and equates this to experimentally measured static failure load to define a critical impact velocity for impact failure. A granule will fail if the predicted theoretical maximum force during impact due to the impact velocity is greater than the real force required to produce failure in that particular granule.The random nature of granules produces a spread of velocities at which granules of a given size will fail; this spread is the failure distribution. In this paper it is shown that the failure distribution of a series of impact experiments can be represented by a 2-parameter Weibull equation. The important c-parameter is related to the impact angle and the critical normal impact velocity that is found from static compression tests. Thus the number of granules failing by impact at each velocity can be found by performing static failure tests.