Topology Optimization Design For Porous Lattice Structure And Manufactured By Selective Laser Melting

With the aging population and improved quality of life today,Developing the better implant material to adapted to humans' bone becomes more and more important. Based on the principle of topology optimization, a unit lattice structure of Ti6Al4 V alloy was simulated in ANSYS and then reconstructed in Solidworks.Some design rules and processing restrictions in the SLM were introduced.A series of features structures were designed and manufactured by SLM to provide the basis for manufacturing the porous lattice structure.Based on microstructural and mechanical property evaluation of Ti6Al4 V parts manufactured by SLM,the mechanical properties of tensile samples could reach the ISO standards and exceed the casting state,but still not as the forging state in ductility.The samples which have a heat treatment at 800? for 4h had a better ductility than the samples which was not heat-treated whose have an acicular ?' martensitic microstructure.when the temperature was reached 750?,the particles of ? phase located along the boundaries of ?' needles was appeared which can improve the ductility.The dynamic Young's modulus testing and compression testing of porous lattice structure Ti6Al-4V alloy was conducted.It found that the young's modulus decrease with the increase of porosity when the unit sizes were the same, on the other hand,the young's modulus was also decrease with the increase of the unit size when the porosity were the same,all the values of Young's modulus were in the range of 3.4-55.47 GPa.The compressive strength also has the result,the compressive strength decreased with the increasing of porosity when the unit sizes were the same,and decreased with the increase of the unit size when the porosity were the same,and the value was in the rang of 48-320 MPa.In the compression testing, the porous lattice structure was factured along 45°with the compress direction,in line with Tresca yield criterion.The Young's modulus was only related to the characteristics of material and the internal structure,and independent with layers of the porous lattices.Young's modulus at loading direction in topology optimization was more stiffness than the other directions of the porous lattice structure.C1 represent the structure's Bending resistance when the porosity was the same,and decrease with the increase of the unit sizes.The relationship between the Young's modulus and porosity with the different unit size were obtained by data approximating.It indicate that in order to adapt to human bone's characteristic,the porosity should lager than 61.1%?59.7%?58.4%?57.8%?53.2% when the length of side of the unit lattice structure were 1mm?2mm?3mm?4mm and 6mm.