Investigation on Dynamic Impact Mechanism of Single Crystal Sapphire 3D Model Based on Cohesive Zone Law

Abstract

Based on mesh reconstruction technology, a 3D solid model of single crystal sapphire (SCS) with global embedded cohesive element is established in this study. Using exponential cohesive zone law (CZL), the anisotropy of SCS can be effectively characterized by assigning the mechanical properties of matrix element and cohesive element. Taking the C‐plane SCS model as the research object, the whole process of dynamic evolution of cracks in the model under high‐speed surface impact and high concentrated stress impact is reproduced by finite element simulation technology. The simulation is compared with the experimental results from the aspects of crack initiation morphology, crack propagation path, sample fragmentation form, and mechanical response curve. The dynamic compressive strength reaches 1630.3 MPa with the impact velocity of 30 m s–1 in surface impact type. The initial maximum loading force reaches 320 N when the impact velocity is 8.35 m s–1 in the indentation impact type. In addition, by combining the simulation results, this study clarifies the mechanism of strain rate effect exhibited by SCS from the perspective of stress–strain data and crack evolution characteristics. Therefore, the model established in this study can effectively reflect the mechanical behavior of SCS under impact load.