Design And Research Of Human Cervical Intervertebral Disc Based On 3D Printing Of Metal Porous Structure

Selective Laser Melting（SLM）technology has been applied in the field of medical devices.SLM technology can produce personalized and complex printed parts,which has a great application prospect in the application of personalized human implants.Based on the demand of human cervical intervertebral disc implants,a model of human cervical intervertebral disc implants is designed by using the method of three-dimensional reconstruction of Computed tomography（CT）images,and an implant with porous structure that is compatible with the elastic modulus of human intervertebral disc is designed.The medical stainless steel 316L was selected as the printing material.Through the combination of finite element analysis and experiment,the best laser printing process parameters were obtained and printed.The main research work is as follows:Firstly,the imaging principle of CT images was introduced,and the 3D reconstruction of cervical model was carried out through CT images,and the model surface was repaired and optimized.Then,ANSYS software was used for biomechanical finite element analysis.By applying load and boundary conditions to the cervical spine,it was bent and deformed,and the movement and deformation of the upper and lower vertebral bodies and intervertebral discs of the cervical spine were analyzed.Then,according to the application of the implant in the biomedical field,the design and manufacturing requirements of the artificial disc implant were analyzed.The rhomboid dodecahedron porous structure was adopted as the design structure,with the optimal parameters of 1.2mm and the arm diameter of 0.3mm.Then,according to the CT images of cervical spine and the 3D reconstruction model,the intervertebral disc model was established,and the intervertebral disc model with the designed dodecahedral porous structure was finally obtained by Boolean operation.Then,the selective laser melting process was numerically simulated,and the changes in the shape and size of the molten pool were simulated by changing the laser processing parameters in Flow-3D software.The laser power of the better parameter combination was selected between 130 and 160 W,and the scanning speed was between 700 and 850mm/s.Finally,the orthogonal test method was used to study the optimal forming process parameters combination of 316L stainless steel material.By comparing the influence of different parameters on the printing results,the optimal process parameters were obtained in the laser power of 160W and scanning speed of 700mm/s,presenting better printing results.The equivalent elastic modulus E and compressive strength σ_bc of the porous cervical implant were about 14.07 GPa and 45.6 MPa,which basically met the design requirements of the implant.