Characterising failure of armour ceramics at high strain rate loading : experiments and simulations

Abstract

Advanced ceramics used in armour applications are subjected to extreme loading conditions and hence understanding their failure under impact loading conditions helps in the development of materials with improved dynamic properties. Though the experimental techniques that characterize their strength and failure under impact loading conditions give a good estimate of failure strength, they fail to provide a comprehensive understanding of the failure mechanisms due to the limitations associated with the high speed imaging techniques. So, often the experiments are complemented by the finite element simulations to understand the failure processes. In the current study, the high strain rate behaviour (of modified Split Hopkinson Pressure Bar tests) of extensively used armour ceramics such as Silicon Carbide, Boron Carbide, and Alumina are studied using finite element simulations in ABAQUS/Explicit. Initially efforts have been made to validate the numerical model and to understand the effect of varying experimental parameters and other properties on the deformation behaviour. Comparative study of the mechanical deformation behaviour of the different materials including stress distribution and damage evolution as well as estimation of their compressive strength and failure strains were done. Influence of geometry was also investigated. Finally, characterization and miniaturized-SHPB experiments were conducted on Reaction Bonded Silicon Carbide samples, with an attempt to correlate the microstructure and mechanical properties of the material with the dynamic results.