Analysis of three point bending mechanical properties of functionally graded triply periodic minimal surfaces

SHI Yaochen; HAN Jinhu; DUAN Haitao; LU Zhiyi; YANG Fengshuang; DU Yingyu

doi:10.16579/j.issn.1001.9669.2026.04.015

Abstract：[Objective]TAiming at the limitation of unidirectional linear gradient of porosity in the gradient design of triply periodic minimal surfaces,the influence of porosity and gradient design on the three-point bending mechanical properties of porous structures based on Primitive surface was studied,and a porosity gradient optimization method adapted to the structural stress distribution was proposed.[Methods]Firstly,three uniformly thick porous structure models with different porosities were constructed based on the implicit function of Primitive surface,and the influence law of porosity on the structural mechanical properties was clarified.Secondly,an M-shaped porosity gradient design scheme was proposed according to the stress distribution characteristics of the uniformly thick structure under three-point bending load,to realize precise regulation of porosity in high stress areas.Then,the specimens were fabricated by stereo lithography apparatus technology,and finite element simulation under three-point bending condition was carried out based on Ansys software.Finally,three-point bending tests were conducted to analyze the influence mechanism of porosity and gradient design on the bending mechanical properties of the structure.[Results]Results indicate that the flexural performance of the uniformly thick porous structure is negatively correlated with the porosity.When the porosity decreases from 35%to 30%,the bending stiffness increases by 53.6%.Compared with the uniformly thick structure with 32.5%porosity,the M-shaped gradient structure has a 17.8%increase in bending stiffness,a 28.2%increase in strength,and only a 3.7%increase in mass.This method can effectively alleviate stress concentration,improve the flexural performance of the porous structure under the premise of lightweight,and provide a reference for the gradient optimization design of porous load-bearing structures.