HIGH-SPEED IMPACT RESPONSE OF PARTICULATE METAL MATRIX COMPOSITE-MATERIALS - AN EXPERIMENTAL AND THEORETICAL INVESTIGATION

A combined experimental and numerical investigation of the high strain rate behaviour of ceramic particle reinforced metal matrix composites (MMCs) has been undertaken. Experimental results consisting of dynamic penetration tests (DPT), Taylor cylinder impact (TCI) tests, split Hopkinson pressure bar (SHPB) tests, and conventional mechanical tests are presented. A flow stress model based on isotropic plasticity theory has been developed and implemented into the DYNA2D finite element hydrodynamic code. The model is especially suited for describing the behaviour of MMCs as it provides for a smooth transition from brittle to ductile type behaviour with increasing values of hydrostatic pressure. This constitutive model is phenomenological in nature, and reduces to the more familiar Johnson-Cook (J-C) and Zerilli-Armstrong (Z-A) flow stress models as special limiting cases. The parameters of these models were calibrated based on the SHPB test results. Hydrocode simulations of the TCI tests were conducted in order to validate the models at high rates of loading. The satisfactory agreement between predicted and measured post-TCI profiles provided confidence in applying the code to numerical simulation of the DPTs. Computational results are presented and correlated with the corresponding experimental data for both reinforced and unreinforced systems. Finally, the advantages and shortcomings of hydrocodes for predictive purposes are discussed.