Research On Design Method Of Personalized Porous Titanium Alloy Implants Based On Additive Manufacturing

The modulus of elasticity of traditional dense titanium implants is much higher than that of human bone,resulting in stress shielding and bone resorption.Designing them as porous structures to form trabecular-like structures is an effective way to reduce stress shielding.However,currently,some trabecular structures do not consider the actual loading state of bones in different parts of the human body,and their mechanical properties do not consider the personalized differences of different patients.Therefore,it is essential to study the design method of personalized porous titanium implants matched with human bone.In this paper,firstly,the loading state of bones in different parts of the human body is studied,and the tibial implant subjected to compression shear load is taken as the research object,and its personalized design is carried out through a combination of inverse and forward design,and several trabecular layers are divided according to the threshold of cortical bone in the implantation area,and the elastic modulus required for different trabecular layers is determined according to the mechanical properties of bones;Then,the porous structures subjected to compression and shear loads are designed by topology optimization,and its strut diameter-porosity fitting model are studied;Next,the differences in mechanical properties and permeability of different types of porous titanium alloys were studied to determine the filling structure suitable for compression and shear loading implants;Finally,the regulation model of the mechanical properties of porous titanium alloy is studied,the porous titanium alloy with corresponding parameters is selected for filling,and the molding placement angle of the implant is simulated to reduce thermal deformation,and finally used selective laser melting technology to mold personalized porous titanium alloy implants.The results show that: 1)Based on the loading state of the tibia of the knee joint,we designed a solid model of a personalized tibial implant and inserted it into the tibial osteotomy region,and determined the elastic modulus of the tibial stem between 3.031 and 10.528 GPa.2)Two types each of compressive and shear resistant cell structures(TO-P1,TO-P2,TO-S1,TO-S2)and four common cell structures(BCC,FCC,RDC,DCC)are designed by topology optimization,and the strut diameter-porosity fitting model of cell structures was established.3)The mechanical properties and permeability of the porous titanium alloy are comprehensively compared.It is concluded that the TO-S2 structure has the best overall performance and is most suitable as a filler structure for compression-shear loading implants.4)The mechanical property regulation model of porous titanium alloy is established.The diameter of the porous titanium alloy strut for tibial implants is determined between 0.106 and 0.202 mm,and the tibial stem is filled with porous titanium alloy.Finally,according to the heat deformation simulation results,the porous tibial implant is printed and moulded with a placement angle of 45°,and the forming effect is good.