Visualization of Early Stage Damage Propagation During Hypervelocity Impacts on Brittle Materials

The final outcome of an impact event (crater size, penetration depth) can be affected greatly by damage accumulation at early stages of the impact event when non-tensile stress states dominate. We have conducted hypervelocity impact experiments on bonded basalt/pyrex specimens utilizing high speed imaging to investigate the damage evolution at times before waves reflect from the lateral specimen boundaries. Results show that significant damage accumulates before the arrival of tensile release waves often associated with failure of brittle materials. Initially, a diffuse damage front propagates into the specimen at a speed close to the shear wave speed. As this damage front slows spatial instabilities appear along the damage front, which develop into localized damage zones.