This paper is focused on the in-plane crushing of two-dimensional (2D) porous structures with a special attention on the effect of functionally graded (FG) porosities. The dynamic response and energy absorption of closed-cell metal foams with different porosity distributions are investigated by using finite element (FE) analysis. Two symmetric, two asymmetric and one uniform distributions of internal pores along the impact direction are constructed with Voronoi tessellation. The proposed porous structure is crushed under the impact of a rigid panel with a constant velocity. The deformation of cell walls is simulated using a plastic kinematic material model. The erosion criteria and hourglass control are applied to ensure the accuracy of numerical results, which are validated against the experimental data from open literature. The effects of varying parameters on the energy absorption, deformation pattern, and stress-strain curve of the FG porous structure are discussed. The dynamic response is found to be influenced by different random cell geometries, porosity gradients, cell wall thicknesses, internal pore numbers, and impact velocities. The effective way to improve energy absorption capability of the porous structure under a constant-velocity impact is proposed, shedding new insights into the deformation mechanism of the FG porous structure for engineering design.

本文重点研究二维（2D）多孔结构的面内破碎，特别关注功能梯度（FG）孔隙率的影响。通过有限元分析，研究了具有不同孔隙率分布的闭孔金属泡沫的动态响应和能量吸收。利用Voronoi镶嵌构造了沿冲击方向的两个对称，两个不对称和一个均匀的内部孔隙分布。所提出的多孔结构在刚性面板的作用下以恒定速度被压碎。使用塑性运动材料模型模拟细胞壁的变形。应用侵蚀标准和沙漏控制以确保数值结果的准确性，并根据公开文献中的实验数据对其进行了验证。讨论了不同参数对FG多孔结构的能量吸收，变形模式和应力-应变曲线的影响。发现动态响应受不同的随机孔几何形状，孔隙率梯度，孔壁厚度，内部孔数和冲击速度的影响。提出了提高恒速冲击下多孔结构能量吸收能力的有效途径，为工程设计中FG多孔结构的变形机理提供了新的认识。