Study On Mechanical Behavior Of Stainless Steel Diamond Lattice Structure Manufactured By Laser Powder Bed Fusion

316L stainless steel is a widely used engineering material with excellent corrosion resistance and comprehensive mechanical properties.Porous structures are widely used in lightweight,biological implantation and buffering and energy absorption due to their advantages of light weight,high specific strength,energy absorption and shock absorption,noise reduction and heat insulation.Triply periodic minimal surface(TPMS)porous structure is caused extensive research by researchers by its advantages such as zero mean curvature at any point on the surface,periodicity in three independent directions,various geometric shapes,and parameterizable mathematical modeling.The rapid development of additive manufacturing(AM)has improved the designability of complex three-dimensional structures,which has greatly promoted the research of porous structures.Porous structures will inevitably be affected by impact loads during actual use.However,the mechanical properties and deformation behavior of Diamond structures prepared by laser powder bed fusion(L-PBF)technology under impact loads such as explosion and collision It is not clear,so it is necessary to carry out the study of the Diamond structure prepared by laser powder bed fusion technology under shock loading.In this paper,to provide theoretical basis and guidance for engineering application,four kinds of Diamond structures with the same relative density were designed,the stress-strain relationship,deformation failure behavior and energy absorption capacity of 316 L stainless steel Diamond structure manufactured by L-PBF under quasi-static load and dynamic load were systematically studied by the way of combining the numerical simulation and experimental,and the strain rate effect of 316 L stainless steel substrate was studied.The main research contents and results are as follows:(1)Design and fabrication of the Diamond structure.In this paper,the relationship between relative density and level set constant was obtained by MATLAB,and then four Diamond structures were designed using MATLAB,namely gradient skeleton Diamond(GSKD)structure,gradient sheet Diamond(GSHD)structure,uniform skeleton(USKD)Diamond structure,uniform sheet Diamond(USHD)structure.Then use MATERIALSE MAGICS to perform thickening,boolean operations and other operations to obtain.STL files for printing,and use EP-M150 to prepare samples.The above four voxelized Diamond models for finite element simulation were obtained using MATLAB code,and saved as.INP files for importing into ABAQUS for finite element simulation.(2)Research on mechanical properties of 316 L stainless steel matrix prepared by L-PBF.The mechanical properties of 316 L stainless steel under quasi-static and dynamic loads were tested by universal electronic testing machine and split Hopkinson pressure bar(SHPB).The effect of strain rate on the stress-strain relationship,yield strength and strain hardening ability of 316 L stainless steel was investigated,and the corresponding Johnson-Cook plastic constitutive model was established.The results showed that the 316 L stainless steel prepared by L-PBF has obvious strain rate effect.(3)Study of quasi-static compressive behavior of 316 L stainless steel Diamond lattice structure prepared by L-PBF.The quasi-static mechanical properties of four types 316 L Diamond lattice structures under the strain rates of 0.001/s and 0.01/s were tested by a universal electronic testing machine.The compression deformation process of the lattice structure recorded by the camera.The compressive deformation behavior and failure mechanism were analyzed with the stress field and strain field simulated by finite element.The results showed that the sheet-like structure had higher compressive strength,which was twice that of the skeleton-like structure;only the GSKD structure showed the collapse and recovery of stress during the compression process;the results of the finite element simulation were consistent with the results recorded by the camera,more The deformation behavior of the skeleton structure was intuitively displayed;when the strain rate increased from 0.001/s to 0.01/s,the strength of all structures increased slightly and the deformation mode did not change.(4)Dynamic compression behavior of 316 L stainless steel Diamond lattice fabricated by L-PBF.The dynamic mechanical properties of four 316 L Diamond lattice structures were tested by using a split Hopkinson pressure bar(SHPB)device at strain rates of 300/s and 800/s.The compression deformation behavior and failure mechanism of lattice structures were analyzed through the compression deformation process recorded by high-speed camera.The results showed that when the strain rate increased from 0.001/s to 300/s,the yield strength of all structures increased significantly,while the deformation mode did not change;when the strain rate increased from 300/s to 800/s,the The yield strength enhancement was not obvious and and the deformation modes of GSHD and USKD structures changed.