Design And Manufacture Of 3D Printed Ankle Orthopedic Device Based On Finite Element Analysis

Objectives:The purpose of this study is to explore an efficient manufacturing method and process of personalized ankle orthosis(AFO)by using 3D printing technology,and to verify its practicality through finite element analysis method.The maximum stress and maximum strain of five different arch height models were compared by finite element method,and an optimal arch height(maximum stress and maximum strain)was selected.The maximum stress distribution cloud diagram obtained by finite element analysis is used to optimize the orthosis to enhance the air permeability and practicability and reduce the cost without affecting the stress.The effects of different arch heights on the maximum stress and strain of the foot were also discussed.Methods:The Gscan intelligent full-color handheld 3D scanner manufactured by wuhan zhongguan company was used to collect the models of the legs and ankle feet of patients at the position where they bent their knees and walked on the stool.The 3D model data collected is then saved in the format of STL.Geomagic studio software is used to take the model in turn:Broken fragments deletion,model file position of the shearing edge deformation,on the basis of curvature with leg back filling repair failed to scan to the area,according to the anatomical structures for foot bony bump position such as external ankle,heel position such as extended to set aside enough space to prevent the occurrence of skin wear these areas in use process,the foot inside area to be indented inward by burin function,Correct scan positions lead to sufficient evaginate,use set up five regional deformation gradient height use area deformation control foot arch,key points,in turn,correcting the strephenopodia problems,shear model in order to shape the appearance of the orthoses,use sandpaper and overall relaxation functions inside and outside the smooth surface to reduce friction,make the whole model to model the overall pump shell out 5 mm,thickening function will use shell model thickening,2 mm,using reverse engineering processing precision surface function:According to detect contour curvature and rest according to the detection of contour line march another build manually generated by the curved surface piece for 250,generating surface by manually move adjust the average distribution of the finished surface and shape rules,using the repair surface function adjust surface intersection and bad point problem,keep the default values for grating formation,on the basis of the default constants for the formation of the fitting surface(NURBS),to convert the model to convert surface to CAD model,to save files in STP file format.Results:By comparing the five different height of the maximum stress distribution nephogram and arch of the foot arch center of maximum’ stress and strain of the maximum value in the process of change over time,found that with the increase of the arch height,the maximum stress of the arch center has been changed,when the arch height of 0 mm maximum stress is 499.427 MPa,the center of the arch in the arch height is 2 mm when the maximum stress is 319.968 MPa,the center of the arch in the arch height is 4 mm maximum stress is 275.894 MPa,the center of the arch.When the arch height is 6 mm maximum stress is 256.339 MPa,the center of the arch in the arch height is 8 mm when the maximum stress is 285.076 MPa,the center of the arch in the arch height is 10 mm maximum stress is 336.077 MPa,the center of the arch in the arch height of 0 mm maximum strain point of maximum strain was 30.4042,when the arch height is 2 mm maximum strain point of maximum stress is 31.1568,when the arch height is 4 mm maximum strain point of maximum stress is 29.4501,When the arch height is 6mm;the maximum stress of the maximum strain point is 28.0691;when the arch height is 8mm,the maximum stress of the maximum strain point is 29.7402;when the arch height is 10mm,the maximum stress of the maximum strain point is 22.59.According to the results,it can be known that the plantar stress is the minimum when the arch height is 6mm,which is the optimal result.At the same time,according to the maximum strain analysis,the lateral malleolus strain point is the second smallest when the arch height is 6mm,which also supports the conclusion that the arch height of 6mm is the optimal result.Conclusion:In this study through the finite element analysis to establish the optimal arch made of ankle foot orthoses method greatly reduces the time cost in the process of ankle foot orthoses made and material cost,and through the finite element analysis,can make up for the use of 3 d scanners cannot plantar data this defect,greatly increased the 3 d printing,and the availability of 3 d scanner in clinical application.This method is worthy of being popularized in clinical practice,and the establishment of the arch height gradient model and the use of finite element analysis to screen the most stress-strain height of the arch also provide new ideas for future clinical applications.