Research On Structural Stiffness And Strength Of Resilient Wheel

The material of the elastic element assembled between rim and disc is rubber which is a kind of a typical hyper-elastic material. In the case of large deformation, large strain, the stress-strain relationship has an evident nonlinear characteristic. The properties of rubber material contain nonlinear, hysteresis, hardness, stiffness, creep and stress relaxation characteristics. To facilitate the application of the simplified procedure, the approximate mathematical model is established to simulate the stress-strain relationship based on hyper-elastic material theory and linear viscoelastic theory.Based on a certain type of resilient wheel equipped high-speed trains, the structure of rim and mounting parts are optimized to fulfill the operating needs of the urban railway vehicles and build nonlinear finite element models. By comparing calculations of different FE models, the shape and interference of the rubber blocks can be determined. And then the hardness and materials nonlinear models parameters would be confirmed. According to the standard UIC810-1, UIC812-1and ISO683-1, the steel properties of the rim and core should be definite, which include material parameters, static strength allowable stress and fatigue strength allowable amplitude of stress.The finite element model is established in FE code Hypermesh and finished the modal analysis in nonlinear FE code ABAQUS. The natural frequencies and corresponding mode shapes of the whole wheel and its separate steel parts, i.e. rim and disk are computed. The rim, disc and the whole wheel modal have been studied. The natural frequencies of each part under the same or different vibration modes have been discussed. The relationship of vibration mode and natural frequency between the whole wheel and various parts of the wheel has been analyzed. Based on UIC510-5and en13979-1, the radial stiffness, axial stiffness, torsional stiffness and deflection stiffness have been calculated by the finite element method. The analysis results show that the elastic part structure and material properties mainly affect the elastic stiffness characteristics of the wheel. The resilient wheel stiffness in different directions stays steady. The linear displacement and angular displacement enhance with the increasing of loading.According to UIC510-5and EN13979-1, the pre-stress and static strength analysis result have been calculated in nonlinear finite element method, which shows that the surface stresses inside the rim decrease with the declining of rim thickness, because of rubber elastic element’s extra materials the maximum stress appears around extruded regions. In the static cases, the maximum stress appears in the rim inner side surface. The rubber blocks make influence on the core area. The compressive stress is uniform continuous and smaller in the area whose stiffness is the larger on the core. With the deformations of rim area absorbed by rubber blocks, its effects on the core area would be reduced.The method, which is presented in the standard UIC510-5, about multi-axial stress transformed to uniaxial stress has been studied and programmed. The fatigue strength calculation results indicate that mean stress and stress amplitude in rim internal surface raised section are higher than others regions. Comparing with the original structure, stress amplitude and mean stress are reduced. The mean stress and the amplitude of stress in the transition area between disk and hub are higher than others regions which are dangerous zones.