Numerical modeling of dynamic response and microcracking in shock-loaded polycrystalline transparent ceramic

Transparent ceramics are promising materials in the fields of high pressure and high temperature. Based on a lattice-spring simulation method, a novel polycrystalline model for shock-wave compression is established to explore the dynamic response and damage evolution of yttrium aluminum garnet (YAG) under shock loading. The macro-response and micro-fracture process under impact loading can be obtained simultaneously, and a correlation between the macroscopic response and mesoscale damage is shown. The process of crack propagation along a grain boundary and through grain-boundary deflection is observed in the simulation. A change in deformation behavior from intergranular fracture to transgranular fracture in the vicinity of grain boundaries, associated with the transition from an elastic response to a plastic response, is observed, as the shock stress increases from below to above the Hugoniot elastic limit. Computational results demonstrate a clear, exponential attenuation of the elastic precursor wave with the propagation of shock waves. The reasons for the elastic precursor decay and the transition from an elastic response to a plastic response are the stress relaxation and energy dissipation caused by internal transgranular fracture. The polycrystalline model will aid in microstructure design and provide a reference for the development of polycrystalline transparent ceramics in the fields of engineering and scientific research.