Optimization Design And Fatigue Life Analysis Of Rubber-Metal Spherical Hinge Structure

The rubber elastic element is the element that bears and transits the vertical load in the vehicle suspension system and has the function of alleviating and restrains the impact caused by the road surface.In this paper,the rubber-matal spherical hinge used in subway vehicles is taken as the research object.A 3D finite element model of the rubber-matel spherical hinge structure is built to simulate the fatigue life of such a structure.Taking the rubber layer profile as the optimization object,through the layered design method of rubber layer profile,the modified variables and objective function are determined,and the structural optimization design of rubber-metal spherical hinge structure is performed.The numerical simulation of the optimized rubber spherical hinge structure is carried out through the finite element method,and the stiffness and fatigue life of the optimized structure are analyzed and verified by experiments.The research results can provide technical reference for fatigue life prediction and optimization design of rubber-metal spherical hinge.The research contents and results are as follows:(1)According to the fatigue test data of rubber specimens,A Mooney-Rivlin hyperelastic constitutive model is used to analyze the fatigue test data by using the nonlinear regression method,and the model parameters are identified;Using the ABAQUS software,a 3D finite element model of rubber spherical hinge structure is constructed,and the fatigue life of rubber spherical hinge structure under tension and torsion cyclic load is studied by using the finite element simulation.The results show that under tension and torsion cyclic load,the minimum fatigue life of the structure appears on the characteristic parts among 90o-180orubber surface closing to the metal jacket and the mandrel in the radial direction,and the minimum fatigue life is 1.292million cycles.The results show that the fatigue life and failure location of the simulation are consistent with the test results,which verifies the effectiveness of the finite element simulation.(2)The causes of cracks in rubber layer of rubber spherical hinge structure are analyzed.It is shown that the main reasons leading to the failure of rubber material are unreasonable design of original structure geometry,non-uniform distribution of stress and strain,too small precompression and surface fold.Taking the diameter parameter ratio S before and after optimization,and thickness variation U as well,as the optimization variables,the layered design method is used,and the variation rules of stiffness coefficient K,maximum strain?_max,maximum stress?_maxand stress-strain comprehensive factor M with parameters S and U is investigated.Taking the minimum M as the optimization objective,the annealing optimization algorithm is used to carry out iterative calculation to obtain the values of the parameters S and U.The results show that the minimum value is obtained when the value of design variable S is equal to 1.03 and the that of design variable U is equal to 0.89 mm.(3)Under the cyclic load of radial tension and axial torsion displacement,the finite element numerical simulation of the optimized rubber spherical hinge structure is carried out by using the ABAQUS software.The stiffness coefficient of the rubber spherical hinge structure is about 11.62k N/mm,which meets the limited stiffness requirements.Comparing with the original structure,the fatigue life of the optimized structure increases from 1.292 million cycles to 2.676 million cycles,and the fatigue life of the optimized structure is about 2.07 times of that of the original structure.The calculated fatigue life of the optimized rubber spherical hinge structure is tested and verified.Under the same tension and torsion cyclic load conditions,the calculated fatigue life of the rubber spherical hinge was 2.676 million cycles by using the finite element method,and the average test fatigue life was 2.7508 million cycles.Taking the average test fatigue life as reference,the relative error between the fatigue life calculated and the test fatigue life was only 2.72%.The results show that the finite element numerical simulation results are effective and reliable.