Experimentally validated strain rate dependent material model for spherical ice impact simulation

A strain rate sensitive ice material model for spherical-geometry hail ice impact simulation has been developed using experimentally-measured strain rate dependent ice compressive strength data. Simulations of spherical ice impacts compared to dynamic force history measurements were found to be in close agreement with each other. The overall trend of measured peak impact force versus projectile kinetic energy was also compared, showing a strong correlation with the data. The scatter in the measured ice compressive strength data was incorporated in the model definition which in turn was found to capture the upper to lower bounds of the scatter in the measured ice sphere impact forces. Observations of the failure progression of an ice sphere during impact were made using high speed video. The simulation-predicted failure progression was found to match with the crack propagation developing during the impact experiments, thereby demonstrating that the model is representing the basic physics and phenomena governing spherical ice impacts, particularly the initial formation and growth of longitudinal cracks, and how these cracks relate to the development of peak impact force.