Research On Digitized Manufacturing Of Customized Orthosis Based On 3D Printing

With the aggravation of the aging population,the frequent occurrence of various production accidents and traffic accidents,as well as many factors in daily life,the disabled population in China is gradually increasing and the demand for orthosis in our society is also increasing.Orthosis,as an external device for assisting limb rehabilitation,plays a most important role in the rehabilitation treatment of patients' injured limbs and their return to society.But at present,there is a certain disparity between the quantity and quality of orthosis in China and the market demand.It is significant to study the digitized manufacturing of orthosis.It's not only to serve patients better,but also to exploiting the market potential of orthosis and improve the manufacturing level of orthosis in China.The research of digitized manufacturing of orthosis based on 3D printing includes three main tasks:(1)digital modeling of orthosis;(2)strength analysis and structure optimization of orthosis;(3)physical production and evaluation of orthosis.In order to solve the problem of digital modeling of wrist orthosis,after completing the preparatory work before acquisition,the data of patients' wrist surface were obtained by using three-dimensional laser scanner,and the abnormal facets,holes and redundant data in the scanned data were processed by means of VXmodel data processing software.On this basis,the preliminary data model of the orthosis was obtained.According to the preliminary model of orthosis and the actual wearing needs,in order to avoid the pain caused by the compression of the ulna or radius caused by the orthosis structure,the overall outward migration and thickening of the model were processed.Using the method of parametric surface reconstruction in rectangular domain,the digital entity model of wrist orthosis is reconstructed by extracting orthosis contour,dividing surface patches and constructing grids in the precise surface function of Geomagic reverse software.As an important auxiliary device,the strength of orthosis is a key factor affecting the quality of orthosis.In this paper,the reconstructed digital model of orthosis is imported into ABAQUS in STEP format,and the corresponding parameters and boundary conditions were set.The strength of orthosis was analyzed under normal wear and sudden concentrated load near ulna.The results show that,in both cases,the maximum stress oforthosis less than the allowable stress of material,the strength is sufficient and the displacement can be ignored.And then,the other seven groups of orthosis with different wall thickness were analyzed under the same load and constraints.According to their performance,combined with production efficiency,manufacturing cost and many other factors,the optimal wall thickness of orthosis was determined to be 4mm.To optimize the structure of wrist orthosis,after satisfying the strength condition,a continuum topology optimization model based on SIMP method was adopted.The structure of orthosis was optimized in ABAQUS with minimum strain energy as the objective function and no more than 45% of the original model volume as the constraint condition.Based on the results of topology optimization,several ventilation holes were set up in the corresponding parts of orthosis.After verification by finite element method,the strength of the open orthosis can still meet the demand and it has more advantages in air permeability,consumables and weight.Finally,the physical fabrication of orthosis was completed by selective laser sintering technology.After pretreatment,a special data file which can be recognized by the former was generated.In the forming stage,the orthosis was manufactured in AFS-500 former and then was post processed.Orthosis can fit well with the wrist of patients,and the wearing effect is good.The manufacturing time and cost of the whole orthosis is higher than that of the traditional gypsum orthosis,but the digital method has strong adaptability and can be used in many parts of the human body,such as hip,elbow,neck and so on.It has certain popularization value.There are 52 figure,3 tables and 62 references.