Dynamic response and failure analysis of nanoporous Al plate under compression and stretching

It is widely known that porous structure design is an important way to reduce the weight of matrix materials. However, there is still a lack of systematic understanding of how factors such as the shape, size, and concentration of pores affect the dynamic response of materials. This study investigated the elastic-plastic behavior and failure characteristics of nanoporous Al from a molecular dynamics perspective, taking into account columnar voids with a diameter of 2-18 nm and two types of arrangement configurations. The results show that all samples undergo elastic deformation for a strain range of ∼−4% to 5%. In this range, the amplitude of temperature and stress changes with strain decreases sequentially as the sample density decreases. The corresponding yield stress of the void sample under compression and tension is calculated according to the virial theorem. During the compression process, local plastic deformation and collapse mechanisms of voids can occur in low porosity samples, while strain localization and slip thickening mechanisms can occur in the transverse ligaments between large voids. During the stretching process, local plastic deformation and lateral expansion mechanisms of voids can occur in low porosity samples, while strain localization and necking fracture mechanisms can occur in the transverse ligaments between large voids. Finally, the transformation law of deformation mechanism with porosity was given based on the amount of plastic deformation.