Structure Design And Mechanical Performance Study Of Lattice Metamaterials

Lattice metamaterial structures are able to maintain excellent mechanical properties even at low relative densities and have been widely researched and applied in load-bearing and energy absorption applications.Currently,many lattice structures made of metal or polymer materials have been studied and verified for their energy absorption performance.In this project,a lightweight and porous structure with outstanding mechanical properties was designed based on the body-centered cubic(BCC)lattice structure,and two reinforcement structures are proposed.Numerical simulation analysis was carried out using ABAQUS software,and systematic experimental research was conducted on polylactic acid(PLA)samples using 3D printing technology.The results revealed that a suitable combination of vertical and inclined struts in the lattice structure has great potential for further improving the mechanical properties of truss structures.In terms of structural design,this study proposes a novel structure based on the bodycentered cubic(BCC)lattice structure,namely the Truss-lattice-cube(TLC)structure which adds a cubic truss in the center of the BCC structure.The size of the central cube truss affects the mechanical performance of the lattice structure,and an optimum size of 5mm has been determined under the condition of fixed unit cell length(15mm).Based on the TLC structure,two structural improvements to enhance mechanical performance were explored:strengthening the lattice node,referred to as TLC-Str(TLC-Strengthened),and adding a truss cube to the frame of a single cell,referred to as TLCC(Truss-lattice-cube-cube).In terms of experimental testing,lattice structures made of polylactic acid(PLA)material were fabricated using additive manufacturing technology,followed by quasi-static uniaxial compression experiments aimed at analyzing the structural deformation characteristics of the samples under stress.The experimental results showed that compared with the BCC structure,the mechanical properties of the new structure were significantly improved.For instance,in comparison to the BCC structure,the TLC,TLC-Str,and TLCC structures exhibit a significant increase in initial yield stress,with respective increments of122%,211%,and 533%.At a strain of 0.5,the TLC,TLC-Str,and TLCC structures also demonstrate substantial enhancements in specific energy absorption,with respective increases of 96.4%,126.7%,and 172.7%.Furthermore,the specific strength of these structures increased by 293%,316%,and 213%,respectively.In terms of numerical simulation,two finite element models were created: an idealized model and a model incorporating defects and material damage.Using ABAQUS simulation software,the mechanical performance of newly designed lattice structures and BCC structures was compared and analyzed against experimental test results.The results indicated that the three new structures exhibited significant improvement in mechanical performance compared to the BCC structure.In particular,the new structures demonstrated superior energy absorption and load-bearing capacity while maintaining the stable yield response of the BCC structure.Furthermore,the numerical simulation incorporating the defects and material damage model matched well with the observed location and range of local failure areas in experimental testing,indicating good consistency between the two results.In summary,the newly designed lattice structure boasts a higher initial yield stress,specific energy absorption and specific strength,and exhibits exceptional energy absorption and load-bearing capacity,with a relatively stable and sustained stress platform after yielding.This study suggests that introducing appropriate vertical struts can effectively maintain the structure’s stability and improve its stress post-yield response and energy absorption performance after yielding,which is crucial for enhancing the mechanical performance of lattice structures.The combination of suitable vertical and inclined pillars to form a unit cell has enormous potential to further enhance the mechanical performance of lattice structures.