Study On Porous Structure Of The Diamond Unit Cell Design And Optimization Based On Selective Laser Melting

Porous lattice structure is a new multifunctional material,which interior is interconnected by a network structure consisting of a periodic unit,and it is born with relatively low density,high strength,large specific surface area,energy and heat dissipation,sound absorption,electromagnetic shielding and other multi-functional characteristics.Selective laser melting(SLM)is a kind of 3D printing process for direct metal forming,with laser scanning the metal powder melted layer by layer to obtain a three-dimensional part.Those parts from this method can be used directly with high strength.On the other hand,SLM technology is a major method of forming porous lattice structure,the parts can be widely used in industrial fields of aerospace,shipbuilding,transportation and so on.This paper seeks to design a periodic unit with a porous structure according to technical characteristics of SLM,then researches on process features,microstructure and mechanical performance of this porous structure.First of all,"diamond cell" porous structure is introduced,which isotropic structure can be used to avoid cantilever defective from layer by layer of SLM,and a porous structure is designed.Unit cell size,Rod diameter and Optimized radius between rods are defined as parameters to design this porous structure.The mechanical properties of the structure can be further improved by changing the Optimized radius.Then,improve the density and mechanical properties of molded parts by blowing smoke test process,to further avoid the porous structure forming the organization cratering.The study found that,after using the blow-smoking process,ultimate strength and tensile modulus of elasticity were increased by 3.06% and 2.16% respectively.Again,a series of models with different Rod diameter and different Optimized radius are obtained by parametric design.The volume fraction and specific surface area can be calculated for each model.Following,models above are shaped by SLM device,and to analyze the formability of each model has been analyzed,the study shows that the porous structure has very good formability,especially the volume fraction of 1.28% of the structural.Due to the difference of process between tiny structure of porous unit and solid,forming processes of porous structure have been introduced in detail in this paper,and some effective measures have been taken to avoid possible interruption phenomenon during forming process.Finally,study on the porous structure of the surface roughness,the reasons for powder bonding in SLM process have been explained;the elastic modulus analysis of porous structure and radius optimization analysis have been researched by mechanical compression test.Based on these,the function curve of radius optimization—modulus has been obtained for this porous structure.