This paper describes comparative analysis of the biomechanical performances conducted on the external fixation devices whose frames are made out of two different material (stainless steel and ...composite material). Biomechanical properties were determined with experimental and FEM (finite element method) models which are used to study the movement of the fracture crack, establish stiffness of the design solutions and monitor generated stresses on the zones of interest. Geometric modeling of two fixation devices configurations B50 and C50 is used as a basis for structural analysis under the impact of axial load. Structural analysis results are confirmed with an experimental setup. Analyzed deflection values in the load and fracture zones are used to define the exact values of the stiffness for the construction design and fracture, respectively. The carbon frame device configuration has 28% lower construction stiffness than the one with the steel frame (for B50 configuration), i.e., 9% (for C50 configuration). In addition, fracture stiffness values for the composite frame application are approximately 23% lower (B50 configuration), i.e., 13% lower (C50 configuration), compared to steel frame. The carbon frame device has about 33% lower stresses at the critical zones compared to the steel frame at the control zone MM+ and, similarly, 35% lower stresses at the control zone MM-. With an exhausting analysis of the biomechanical properties of the fixation devices, it can be concluded that steel frame fixation device is superior, meaning it has better biomechanical characteristics compared to carbon frame fixation device, regarding obtained data for stresses and stiffnesses of the frame construction and fracture. Considering stresses at the critical zones of the fixation device construction, the carbon frame device has better biomechanical performances compared to steel frame devices.
Aiming at the design problem of high lifespan and high bearing capacity of flexspline,taking the fillets and generator as the research object,parametric model are performed in ANSYS by response ...surface method and the central composite design method is used for sampling. The stiffness and stress at three points are selected as observation objects and the influence law of each fillet parameter are obtained. The analysis results show that increasing the size of each fillet can effectively reduce the stress concentration in various places and increase the stiffness. Based on the comprehensive consideration of the stress and stiffness,the optimum structural parameters are selected. In order to increase the stiffness and improve the bearing capacity of the flexspline,the drafting feature is designed at the bottom of the flexspline,and the parameter is analyzed and optimized. The short axis radial deformation of the non-standard elliptical cam generator can be increased to reduce the stress.
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