Research On Design Method Of Medical Porous Titanium Alloy For 3D Printing

As a carrier of bone tissue engineering,porous structure has the advantages of low density,large specific surface area and good fluid permeability,and has become the focus of research in the field of bone tissue.Titanium alloys have good biocompatibility,good corrosion resistance and excellent mechanical properties and are considered to be the best materials for orthopedic implants.However,the traditional porous structure is limited by the manufacturing process,and it is difficult to form a controllable pore structure to meet the individual needs of patients,therefore,a new manufacturing process is urgently needed to solve the above problems.Based on 3D printing technology and TC4 alloy as raw material,the porous structure of TC4 alloy prepared by 3D printing technology was studied from the aspects of design,preparation and post-treatment of porous structure.In the design of the porous structure,the concept of the meta-structure is proposed based on the printing restriction of the porous structure and the implantation limitation,that is,consisting of a series of porous units having the same outer frame and different inner frames.A class of meta-structures is selected as the research object,and the research method of the meta-structure is given.The empirical model of the meta-structure was solved by finite element analysis and the influence of the magnification factor on the mechanical properties of the porous specimen under the same porosity was studied.Three different heat treatment methods were subsequently designed,and the effect of heat treatment on the mechanical properties of the porous structure was evaluated by a compression test.Finally,according to the experimental results,the appropriate meta-structure is selected to construct the bone model.Conclusions:1)The parameters of the empirical model are C₁=0.20239?n₁=1.6142?C₂=1.8968?n₂=1.1256,which are in accordance with the Gibson-Ashby model of porous structure and can better predict the mechanical properties of the specimens formed by the unit.2)Under the condition of constant porosity,the increase of the magnification has no obvious effect on the effective elastic modulus of the structure,and the compressive strength decreases with the increase of the magnification.3)Among the three heat treatment methods,the strength of the test piece was most obviously improved by stress relief annealing.The solution treatment improved the plasticity of the test piece,and the aging treatment did not achieve the desired effect.4)According to the mechanical properties of the femur,the porous femur structure was designed by empirical model,and the practicability of the empirical model was proved.The connection form of the gradient structural unit was demonstrated by using the tibia model,and the feasibility of the meta-structure was proved.