Study On Bearing Characteristics And Fatigue Life Of Rubber Bushing Under Multiaxial Stress State

With the rapid development of China’s economy and industrialtechnology， rubber elastic absorbers have been the promotion andapplication of large area in the automotive，rail vehicles，bridge，machinerymanufacturing and other industries，some areas has gradually replaced themetal elastic absorbers，the rubber bushing is a typical rubber elasticdamping absorber of rail vehicle steering frame，it works on complex andmultiple loading conditions，it is very important for evaluating the bearingcharacteristics and fatigue life accurately. Therefore， building acomprehensive evaluation system to evaluate the bearing characteristicsand fatigue life，providing a theoretical basis for the design of rubbercomponents，it has important theoretical significance and engineeringpractical value.Based on the theory of fracture mechanics theory and the continuumdamage mechanics，fatigue life prediction models of crack initiation andcrack propagation for rubber material had established in this paper.Through the study of corresponding equivalent stress calculation method，putting forward the fatigue life analysis method of rubber components incomplex stress states. Finally，the bearing characteristics and fatigue life ofthe rubber bushing were analyzed by using the finite element analysissoftware ABAQUS, and then verified it by the fatigue test.The main content of this thesis is divided into five sections：1）Constitutive models of rubber materialIn this part，existing constitutive models of rubber materials wereanalyzed，based on the rubber materials mechanics experimental data，eachmodel was fitted，the material constitutive parameters was obtained.2）Bearing characteristics analyze of rubber bushingWith the material constitutive parameters，by using the ABAQUSsoftware and selecting the appropriate constitutive model，two types ofrubber bushing’s bearing characteristics was analyzed，and the compared itwith the experimental results.3）Crack propagation life prediction model of rubber material Based on the theory of fracture mechanics and rubber material fatiguefracture mechanism，through the FCG fatigue test of rubber material，giving power-law relationship between the crack growth rate and tearingenergy，proposing the concept of unit tearing energy innovatively，and thenbuilt the fatigue crack propagation life model with unit tearing energyrange as damage parameters for rubber material.4）Crack initiation life prediction model of rubber materialBased on continuum damage mechanics theory，defined damage strainenergy rate by Ogden strain energy function，and then described thematerial fatigue damage process by it，derived rubber material fatiguedamage evolution equation by quadrature rules，built the fatigue crackinitiation life model with equivalent strain range as damage parameters forrubber material.5）Fatigue life analysis of rubber bushingThrough the FEA of rubber bushing under fatigue loads，combined theequivalent stress calculation method，obtained the equivalent stress ofrubber elastic absorbers in multiaxial stress state，Through the no notchtensile stress-strain relationship to obtain equivalent strain；Then predictedthe fatigue life of the rubber bushing by crack propagation and crackinitiation life prediction model，the prediction life was compared with thefatigue test results and the cause and effect of factors of error wereanalyzed.Finally，the main work and conclusions are summarized，and theprospect of the future research work.