Numerical simulation of the process of Zr₅₈Nb₃Cu₁₂Ni₁₂Al₁₅bulk glasses fragment penetrating into two separated plates and forming debris cloud

Impact of the Zr₅₈Nb₃Cu₁₂Ni₁₂Al₁₅bulk metallic glasses (BMG) fragment on shield plate generates a debris cloud and causes great damage to the hindside witness target. However, conventional FEM and experimental methods are difficult to track the complex formation process and damage behavior of debris cloud. In this study, such process of a 10 mm spherical metallic glasses fragment penetrating into two LY12 separated plates is investigated, both experimentally and computationally. By introducing JH-2 constitutive model, the mechanical properties of Zr-base BMG with high strength and low plasticity are reproduced; Meanwhile, by introducing the FEM/SPH coupling method, the failed element is converted into SPH, thereby simulating the impacting and fragmentation process of the fragment, as well as the characteristics of the transiently generated debris cloud. The simulation results are in good agreement with the experimental observations. During the penetrating process, a large number of stress concentration areas are found inside the fragment, thus promoting the forming process of the debris; the mass and velocity loss rates of the residual fragment at different stages are clarified quantitatively. Further, the debris cloud in space can be divided into three zones according to the morphology, i.e. the reverse motion zone, the debris-dispersion zone and the debris-concentration zone, and the debris-concentration zone is the main factor causing damage efficiency of the witness target.