Design And Manufacturing Performance Of Tibial Implant Based On Medical Stainless Steel 316L Alloy SLM

As one of the most promising technologies in augmentation manufacturing,Selective Laser Melting(SLM)has been widely used in aerospace and biomedical fields.SLM technology has great application prospects in the field of implanting and joint replacement of bio-integrated bone implants by virtue of the characteristics of individualized and complex structures.This article will cut into the need for personalized artificial implants and joint replacement.Model design through a combination of reverse engineering and forward engineering,The use of SLM technology to create an implant with a porous structure that matches the elastic modulus of the human tibia.Printed material was used in medical stainless steel 316L,The basic research and analysis of the forming process,mechanical properties and support structure.The main research works are as follows:(1)Analysis of the design requirements of the tibial implant in the biological field,using a CT scan the 3D data was obtained.the CAD model of the tibia was reconstructed by reverse engineering,Finally based on the sacral model,use the designed regular octahedral porous structure was used to intersect with it.Finally,a tibia model with a porous structure was obtained.Through theoretical calculations and finite element simulation,the mechanical properties of the octahedral porous tibia structure were analyzed,which paved the way of preparing of the tibia implant by SLM molding is paved.(2)Analyzed the important influencing factors affecting SLM forming print quality and explained the forming mechanism.In order to study the optimum molding process parameters of the stainless steel 316L material,method using orthogonal experiment and step-by-step optimization of the multiple sets of parameters was done through single-channel,single-layer and block experiments,it can be obtained that when the laser power is 130W,the scanning speed is 650mm/s,the scanning pitch is 0.06mm,and the powder layer thickness is 0.03mm,which can form a good printing effect formed,and tthe relative density reached 98.9%by the Archimedes drainage method.(3)Performance testing and analysis of stainless steel 316L material by SLM processing samples:Tested dimensional accuracy,porosity and mechanical properties of stainless steel 316L molded parts.Experiments show that the dimensional accuracy of the molded part is less than 0.02mm and the porosity manufacturing error is less than 0.04mm.The SLM forming stainless steel 316L has average hardness is around 305HV.The tensile strength of standard tensile parts is 608.21 MPa,the yield strength is 478.10MPa,the elastic modulus is 193.6GPa,and the elongation after fracture is 37.67%.The porous tensile member has an elastic modulus of 3.63 GPa and has a tensile strength of 18 MPa without a significant yielding stage.The designed octahedral porous structures with different parameters,and compare and analyze the data through compression experiments,It was found that with a side length of 1.2mm and an arm diameter of a 0.35mm the octahedral porous structure is consistent with the mechanical properties of the natural tibia,which laying the foundation for the manufacture of artificial iliac bone implants.(4)Analysis of the theoretical model by suspension structure was done and the effects of different support types and placement methods on the quality of human knee joints were studied.An optimized support structure parameters with block-shaped hollow support was also simulated at 30-degree angular placement.Using optimized processs parameters and support structure parameters.The iliac implants and porous iliac implants were manufactured.The finding of the research verify,the feasibility of SLM molding,which has an important research significance for the clinical application of personalized implants in medicine.