Finite Element Mechanics Analysis And Optimization Of A Novel Customized External Fixator

The novel customized 3D printing external fixator introduced by Xi ’ an Honghui hospital has shown well clinical outcome.However,it is still lack of biomechanical assess and thus could not be directly used in surgery.Therefore,this study focused on establishing a appropriate finite element(FE)method to predict biomechanics of this kind of fixator.This study also could provide theoretical foundation and be useful for both clinic and related research in future.This thesis performed static analysis and consequent geometry optimization based on Abaqus/Standard module.Firstly,the CAD models of both the Ilizarov external fixator and the 3D printing fixator were established using the SolidWorks2012 version software.Then the static FE analysis was performed to predict the biomechanics of them,and the predicted results of the Ilizarov fixator was compared with previous experiment data to verify the accuracy of the FE analysis.Secondly,the validated FE method was used to calculate the biomechanics of both the Ilizarov fixator and the 3D printing fixator under 500 N compressed load,20 N · M torsionload and 200 N four-points bending load,and then comparisons of the compressions tiffness,the torsion stiffness and the four-points bending stiffness of these two fixators were made.Finally,the parametric optimization of the diameter,angle,axial gap,relative position and the eccentric distance for both the pin and half-pins of the 3D printing external fixator were performed using the FE method,and then optimized values of these parameters were obtained.The optimizing paremetes could be concluded as : pin diameter : 5mm,half-pin diameter: 4mm,angle of pin and half-pin : 90°,axial gap : 70 mm,pin in the middle of two half-pins,bone eccentricity distance: the range of bone displacement is about 2mm.The mechanical properties of the photosensitive resin ring of 3D printing external fixator are less changed before and after hollowed-out,and both of them could be used in clinic.In conclusion,this study provided a appropriate geometry size fixator and optimized geometry parameters for the novel 3D printing.It also be benefit for both the mechanical testing and clinical usage of this kind of fixator as well as the surgery programme of the surgeons.Finally,the 3D printing fixator is of excellent application prospect in clinic because of its advantages of automatical reposition and easy to operate surgeriry.