Research On Structure Design And Application Of An Internal Fixator For Treatment Of Fractures

In this research,mechanics characteristic and application of Inside-swell Self-locking Nail(ISN) which is a kind of internal fixator for fracture was studied.Based on the reviewed of international research status and characteristic of kinds of fracture fixators,a finite elemet(FE) based frame work of ISN is proposed.Three-dimensional model and FE model of ISN and thighbone were made.In order to analyze the characters of this internal fixator during the application,the ISN model was combined with the thighbone model in FE environment.Firstly,the three dimensional FE model was built.The method of modeling was based on the CT images of thighbone.And then the images were imported into reconstruction software to build the boned model and remesh the 3D to make it optimal for FE analysis purposes.The meshed model was exported in special format, which can be used in the preprocessor of Ansys.The surfaced model was transformed into volumetric meshed model in order that the volumetric meshed model was assigned for material properities.As result,a three dimensional high quality physical model was built.Secondly,the main characteristics of ISN were researched.The most important character of ISN is using the heating recovery of Shape Memory Alloy(SMA) Ni-Ti, which can simplify the structure of internal fixator.And the other specialities were indicated,such as physical character,erosion resistance and biocompatibility.Then the advantages of SMA comparing with other metals used as internal fixators were analyzed particularly.The biomechanical character of ISN was also studied.At last,mechanics characteristic of ISN was researched bsed on FE method.The constitutive for shape memory alloy was presented,and on the basis of it the FE model was built.The method of solving this model was also discussed.In virtue of FE analysis software,Abaqus 6.7,the boned model was combined with the three-dimensional model of ISN.The stress and strain analysis results indicated that the structure and material properities of ISN can satisfied the design requirements.