Study of Compressive Strength of SiC In Impact Experiments with Divergent Flow

The axisymmetric divergent flow was generated in SiC specimens by impact of spherical (radius of curvature ranging from 170 to 550 mm) copper impactors having velocities 550 to 700 m/s. The specimen-window (sapphire) interface velocities or the velocities of the free surface of the nickel witness plate were continuously monitored by VISAR. The maximum, just prior to the failure, shear stress values achieved in the SiC under different confining stresses are associated with the failure threshold of the material. Both the compressive failure threshold of SiC and the parameters of its inelastic deformation were found by matching the results of the AUTODYN numerical simulation to the experimentally obtained waveforms. The compressive failure threshold of SiC is characterized by a transition from apparently pressure-dependent behavior below the confining stress equal to 1.5 GPa to a pressure-independent behavior at higher confining stresses.