| Conical rubber spring is often used in rail transit,can play a role in shock absorption,increase the comfort of the vehicle.The working conditions of rubber elastic elements in engineering applications are extremely complex.Large deformation and alternating load will cause damage to the products.After the material is damaged,the fatigue life times and the stiffness value will be seriously affected.Therefore,it is very important to understand the fatigue failure factors of rubber products and accurately predict the fatigue life of rubber products.The main work of this paper is as follows:1.On the basis of summarizing the research on fatigue failure of rubber materials at home and abroad,the main factors causing fatigue failure of rubber materials,such as reciprocating alternating load,service environment and formula of rubber materials,are summarized.For rubber materials without initial defects,the fatigue life is generally composed of crack nucleation life,short crack propagation life and long crack propagation life,and S-N curve can also be used to predict the fatigue life of rubber materials.2.In order to accurately predict the fatigue life of rubber products and make the calculated fatigue life consistent with the experimental fatigue life,it is necessary to select an appropriate rubber material constitutive model.By comparing the theoretical and experimental data,it is found that the calculated data of the Mooney-Rivlin model are in good agreement with the experimental data,which indicates that the Mooney-Rivlin model can better simulate the mechanical behavior of rubber materials.3.The three-dimensional finite element model of the structure was constructed according to the original size of the conical rubber spring of the railway vehicle.Firstly,ABAQUS was used to construct the three-dimensional geometric model of the structure,and Hyper Mesh was used to divide the geometric model.Then the physical model of the structure is obtained by assigning material parameters,and the finite element numerical calculation is carried out by adding boundary conditions.The load-displacement curve is derived and the stiffness is checked.Finally,FE-SAFE software is used to calculate the fatigue life of the structure.The calculation results show that the stiffness and fatigue life do not meet the design requirements.4.Isight was used to simulate and optimize the conical rubber spring.According to the requirements of structural design,the length and thickness of the inner rubber layer of the conical rubber spring,the included Angle between the separator and the horizontal line,the distance between the inner rubber layer and the symmetry axis,and the thickness of the outer rubber layer were taken as the optimal design variables,and the orthogonal numerical test with four levels and five factors was carried out.The optimal design results show that the thickness and length of the inner rubber layer have significant effects on the fatigue life of the structure,while the thickness of the outer rubber layer has the least effect.5.Taking the minimum strain as the optimization objective and the geometric parameters determined by orthogonal numerical tests as the design variables,a second-order response surface model was established,and the multi-island genetic algorithm was used to conduct the single-objective multi-factor optimization design of the conical rubber spring under the stiffness constraints.The results show that the stiffness coefficient of the optimized structure is 0.630 k N/mm.Within the range of the design stiffness coefficient,the fatigue life is 4.963 million cycles,and the design fatigue life is 3.5 million cycles.Both the fatigue life and stiffness meet the design requirements.The experimental results show that the calculated fatigue life is in good agreement with the experimental results,and the simulated fatigue failure position is in good agreement with the experimental results. |
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