Surface curvature-dependent strength analysis of three-dimensional nanoporous metals

Abstract

Nanoporous metals have gained recognition for their remarkable surface effects and their demonstration of superior mechanical properties. Previous studies on nanoporous metals often relied on simplified two-dimensional models due to theoretical complexities. However, these simplified models fall short in accurately representing the mechanical properties of nanoporous metals and fail to adequately capture the substantial impact of surface effects, particularly the curvature dependence of nanosurfaces. Therefore, our study employs the principle of minimum energy and leverages the Steigmann-Ogden surface theory of nano-materials to devise a finite element surface element that comprehensively considers the surface effect of nanoporous materials. Utilizing this novel surface element, we construct diverse nanoporous metallic models and subject them to single-axis tension and compression simulations. Our findings reveal that the incorporation of surface bending stiffness leads to a notable increase in the strain energy density of the material, thereby influencing the trend of energy absorption rate. Additionally, Young’s modulus of nanoporous metals is significantly affected by factors such as residual stress, surface bending modulus on the pore surface, and loading direction, as opposed to the surface Lamé constant. The developed finite element model offers a robust and compelling scientific approach for accurately predicting the mechanical performance of nanoporous metals.