Dynamic mechanical properties and failure mechanism of magnesium aluminum spinel based on experiments and peridynamic simulations

Experiments and peridynamic simulations of the split-Hopkinson pressure bar (SHPB) have been conducted to investigate the dynamic mechanical behaviors of magnesium aluminate (Mg-Al) spinel. The high-speed camera and scanning electron microscopy were used to observe the failure process and the fracture surface. In our modified model, the crystal orientation and grain boundary strength were explicitly quantified, accompanied by the dual-horizon peridynamic technique, resulting in high calculation accuracy and efficiency. Then effects of the stress state and strain rate on the failure mechanism of spinel have been investigated with the damage evolution process. Micro-pores tend to be generated at the intersection of grain boundaries, while cracks will propagate along these micro-pores, leading to trans-granular and inter-granular failures. Finally, the microstructure effects on the mechanical properties of spinel have been systemically investigated. The strength and distribution of grain boundaries were found to significantly affect the strength and crack propagation of Mg-Al spinel.