Thermodynamic Simulation And Experiment Of3D Pringing Of Bionic Atirficial Bone With Polyetheretherketone (PEEK)

In recent years, with the growing of human bone trauma and healing around the world,the demand of artificial bone is increasing year by year. The special engineering plasticspolyetheretherketone（PEEK）has many outstanding properties such as excellent wearresistance, bio-compatibility and chemical stability. In addition compared with the otherartificial human bone materials, the PEEKYoung’s modulus is closest to that of human bones.So it is an ideal replacement material of artificial bone and suitable for long-termimplantation in human body. Among many manufacturing methods of artificial bones,3Dprinting technology developed in the1980s has the advantages of fast speed, high precision,high strength and easy customization. So it has gained considerable attention and applicationsin the medical industry, especially in the application of the artificial bone production.Thefused deposition manufacturing（FDM）3D printing technology has the advantages of the safeand convenient applications, without requirement of lasers and simple post-processing ofprototypes. So, it is expected that FDM3D printing with PEEK material will become a verypromising approach in the production of artificial bone, However, as far as the author isaware, there are very limited reports about research in this area and it is believed that theresearch is still at early stage.Therefore, in this dissertation, based on the simulation studyand the experimental investigation of the PEEK material’s thermodynamic property and3Dprinting conditions using the bespoke3D printing test rig, a number of interesting findingshave been obtained. Based on these findings, the PEEK bionic artificial bone is successfullymanufactured under the optimal printing conditions. It is believed that the achievements fromthis study break up the limitation that the PEEK bionic artificial bone can only be made byinjection molding and the laser sintering. It is both theoretically important and practicallyvaluable to carry out the study of the production of artificial bones using FDM3D printingwith PEEK materials.In this study, the "Birth and Death" method in finite element analysis software ANSYSwas adopted. Under the consideration of the material property changes with temperature andconditions of the phase transition, the thermodynamics simulation of the3D printingprototype was conducted using ANSYS Parametric Design Language（APDL）to study. In thesimulation, the influence of three main printing environment parameters on the thermal fieldand the thermal-stress coupled field was investigated. These three parameters are nozzle temperature T1, chamber temperature T2and printing velocity V. The simulation results showthat: chamber temperature T2and printing velocity V are the main factors that affect thethermal field of3D printing, the transient change of thermal field leads to uneven distributionof thermal stress; the uniform distribution of printing temperature field, the improvement ofbond quality and reduction of temperature gradient and cooling rate of the prototype can beachieved through appropriately increasing the chamber temperature and printing velocity,which is beneficial to fully uniform stallization and reduction of the warped deformationcaused by uneven shrinkage, meanwhile, the range of the high-stress area in the bottomdecreases, the fluctuations of the stress weaken and the possibility of detachment of theprototype bottom from printing substrate decreases during printing process; raising the nozzletemperature can help to obtain the good adhesive quality and integral temperaturedistribution, but higher nozzle temperature is not conducive for reducing the temperaturegradient and the cooling rate; the overall impact of the nozzle temperature is not significantand it can be optimised according to the actual needs; the bottom of the prototype has a largetensile stress and high stress concentration at the corner where the warped deformation mosteasily occurs; it is possible to carry out FDM3D printing with PEEK in high-temperaturechamber and at high printing velocity.To verify the findings of the simulations, a PEEK3D printing device has been designand developed based on the FDM principle. The warped deformation mechanism of thePEEK prototype was analyzed. Based on the simulation results, the experimental researchswere conducted on nozzle temperature T1, chamber temperature T2, printing velocity V andlayer thickness H. A Non-contact three-dimensional scanner was used to capture the pointcloud data of the prototype. Then, the comparative analysis was carried out between thecollected point cloud and original3D digital model. It was found that the overall amount ofwarped deformation of the proptotype decreeses with the increase of chamber temperatureand decreese of layer thickness. But this deformation first decreases and then increases withthe increasement of nozzle temperature and printing velocity. There is an optimal condition.Under the experimental conditions, when T1=350℃, T2=130℃, V=30mm/s, H=200μm, thewarped deformation of PEEK prototype was smallest. Among these four variables, it wasfound that the impact of3D printing chamber temperature and printing velocity on thewarped deformation is biggest.In addition, the methods for reducing warped deformation of PEEK3D printing havebeen proposed and evaluated. Then, the optimum3D printing conditions are applied to manufacture the PEEK bionic artificial bone implants. The changes of microstructuremorphology before and after the3D pringting experiments were analyzed using SEM. Theanalysis and experiment results show that by choosing the appropriate printing conditions,FDM3D printing technology can be used to produce the good quality PEEK bionic artificialbone that meets the technical requirements of an implant.