基于表面曲率依赖的三维纳米多孔金属强度分析

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

纳米多孔金属因其显著的表面效应和优异的机械性能而获得广泛认可.受限于理论复杂性,以往对纳米多孔金属的研究往往依赖于简化二维模型.然而,这些简化模型无法准确地刻画纳米多孔金属力学性能,也未能充分捕捉表面效应影响,特别是纳米表面曲率依赖性.因此,该研究采用最小能量原理,基于Steigmann-Ogden表面理论,设计了综合考虑纳米多孔材料表面效应的有限元表面单元.利用这种新型表面单元,我们构建不同纳米多孔金属模型,并对其进行单轴拉伸和压缩模拟.研究结果表明,表面弯曲刚度导致材料应变能密度显著增加,从而影响能量吸收率变化趋势.此外,与表面Lamé常数相反,纳米多孔金属杨氏模量受到表面残余应力、表面弯曲模量和加载方向等因素显著影响.所开发的有限元模型为准确预测纳米多孔金属力学性能提供了一种稳健而令人信服的科学方法.

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 Laméconstant.The developed finite element model offers a robust and compelling scientific approach for accurately predicting the mechanical performance of nanoporous metals.