Mechanical Properties Of Ti6Al4V Different Lattice Structures Prepared By SLM Technique

Selective laser melting technology can be used to prepare Ti6Al4 V porous structures with arbitrary complex shapes.The heterogeneous structures show their unique mechanical and biological properties.In the field of medical implants,porous titanium alloys are considered to be the best way to reduce the elastic modulus and avoid the "stress shielding" between implants and human bones.Therefore,the design and mechanical properties of porous titanium alloys have become a hot topic in the biomedical field.In this paper,the mechanical properties of Ti6Al4 V truss and minimal curved surface lattice structures prepared by SLM are compared and analyzed.The main research contents are as follows:(1)Modeling,preparation and characterization of porous structures.Firstly,three-dimensional software and matlab were used to generate Gyroid structures with hollow cube,G7,BCC,homogeneous Gyroid and gradient distribution.A batch of compression and tension samples composed of different cell sizes were prepared by selective laser melting technology.The prepared porous samples were characterized and microscopically analyzed.It was found that the rod-shaped Gyroid minimal surface structure was very suitable for SLM processing,and there were no bonded unmelted metal pellets on the surface of the sample.The microstructure of SLM samples is mainly composed of acicular brittle α ’martensite.(2)Related physical experiments were carried out on the porous structure.The compression properties,tensile properties and fatigue properties of these five porous samples were studied respectively.In the study of compressive and tensile properties,the maximum tensile strength of the five structures is lower than the maximum compressive strength.Among them,the gradient Gyroid structure exhibits excellent mechanical properties,both of which are better than other structures.It is worth noting that the maximum compressive and tensile strengths of the gradient Gyroid structure are higher than those of the homogeneous Gyroid structure with the same porosity and that the gradient Gyroid structure has a lower elastic modulus.It was also found that the number of unicellular bodies also had an effect on the mechanical properties of the sample.The sample with more unicellular bodies was better than the sample with less unicellular bodies.In the study of fatigue performance of hollow cube,G7 and BCC structures,the fatigue strength ratio of hollow cube,G7 and BCC is 0.13,0.4 and 0.22 respectively,and the fatigue performance of G7 is better than that of hollow cube and BCC structures.The morphology analysis of fatigue fracture of them shows that the fatigue fracture crack of lattice structure is not on the unmelted metal ball.They appear near the pores inside the strut.(3)The quasi-static compression simulation of the porous structure is carried out.The quasi-static compression models of five different lattice structures were established.The mesh division and analysis were carried out through the co-simulation of hypermesh and abaqus.The failure forms and deformation mechanisms of these five porous structures were comprehensively analyzed through the observation of stress-strain nephogram,plastic strain nephogram and compression experiment process.The stress-strain curves obtained by simulation are compared with the experimental results.It is found that the simulation method can better predict the maximum compressive strength of different porous structures.