Ballistic Performance of Bimodal Nanostructured and Nanotwin-Strengthened Metals

Abstract

Bimodal nanostructured (NS) metals and coarse-grained (CG) metals strengthened by nanotwinned (NT) regions are two kinds of novel NS metals with high strength and good ductility. They are potential candidates for bullet-proof material. In this work, numerical simulations based on the strain gradient plasticity model and the Johnson–Cook failure criterion are conducted to investigate the effects of microstructural attributes on their ballistic performance. We find that microstructures can significantly affect limit velocity and maximum displacement of the specimens and that regular distribution of the second phase is helpful to improve the overall performance. For the bimodal NS metals, it is found that, under the condition of same distribution, the second phase needs to have a longer projection perpendicular to the impact direction to achieve better performance. For the CG metals strengthened by NT regions, it is found that microstructures with array arrangement of NT regions have higher limit velocities and smaller relative displacements. It is believed that this study could provide insights into the development of advanced NS metals for ballistic protection.