The Relationship Between Structural Design And Compressive Performance Of 3D Printed Polylactic Acid Sandwich Structure

Sandwich structure is a common porous structure with the advantages of light weight,impact resistance,and high toughness,which is widely used in packaging,shipping,automotive,mechanical and other engineering fields.Among them,corrugated structural materials are most widely used.Currently,most of the research on corrugated structural materials is focused on millimeter grade sandwich structural products such as corrugated cardboard.However,due to the narrow application range and difficulties in processing with traditional processes,there is little research on micro size sandwich structures.3D printing technology can integrate the production of sandwich structures,which can solve the difficulties of processing micro sized sandwich structures.Therefore,in order to supplement the theory of micro size sandwich structures,this topic studies the mechanical properties of micro size sandwich structures fabricated by 3D printing technology.Firstly,micron scale grid,V-shaped,and U-shaped sandwich structures were fabricated using 3D printing technology,and exhibit different mechanical properties from traditional methods.Their peak stress and elastic modulus can be fitted as a cubic function.The compressive performance of the multi-layer grid like interlayer is determined by the relative mechanical strength of the layer.Adding a layer to the grid interlayer has no significant effect on the peak stress,but can increase the elastic modulus by about 60.9 MPa.The deformation mode of multi-layer V-shaped and U-shaped sandwich structures can be determined by the loading path and relative mechanical properties between the panel and the core material.The elastic modulus of V-shaped sandwich structures increases with the increase of the number of layers,while the elastic modulus of U-shaped sandwich structures decreases with the increase of the number of layers.The research results reveal the principle that the number of layers affects the compression performance of sandwich structures,providing experimental and theoretical basis for the design of multi-layer sandwich structures.Secondly,three types of sandwich structures,flush and interlacing,with a thickness of 1 and 1.5 times the core material,and with a thickness of 1 and 2 times the interlayer,were designed using the 3ds Max software.Sandwich samples were prepared using 3D printing technology.The printed samples were subjected to compression test,edge compression test,and side compression test to explore their mechanical properties.The research results show that compared to the flush structure,the interlacing structure can significantly improve the compression performance of the multi-layer V-shaped sandwich structure,but has little impact on the edge compression performance and side compression performance.Increasing the thickness of the core material will reduce the compression performance of the multi-layer Vshaped sandwich structure,but can improve the edge compression performance and side compression performance.Increasing the thickness of the intermediate panel can improve the three-dimensional compressive performance of the multi-layer V-shaped sandwich structure.The results reveal the principle that structural dimensions and load paths affect the failure modes and mechanical properties of sandwich structures.Finally,based on the V-shaped sandwich structure,a V-shaped corrugated structure with a mouth-shaped is designed and fabricated.The static compression test of corrugated structural members was simulated using finite element analysis technology,and the results were compared with the static compression test results of mouth-shaped V-shaped corrugated structural members.The static compression performance of mouth-shaped V-shaped corrugated structural members and the errors in the finite element model were analyzed.It is found that the compressive performance of V-shaped corrugated structural members with notches depends on the edge pressure performance of the sandwich structure on both sides.Structural simplification,material definition,and structural defects in test samples are the main sources of errors in finite element analysis results.