Numerical Analysis Of Key Parts Of Fatigue Damage Of Rubber Joint

Rubber element has good damping effect, it is ofen used in the connection and buffer device of railway vehicle. Fatigue phenomena often occurs when rubber element is used, which lead to the failure of service performance, and further lead to fatigue failure of related components. However, traditional analysis method in which stress is the control factor has been unable to accurately reflect the fatigue failure of rubber. The previous research results of task group show that, on the condition of constant rubber material and application environment, strain concentration, displacement amplitude and temperature rise which is produced by external load are important factors of determining fatigue life of rubber joint.This paper, on the basis of Weida Wang’ research results, changes simple connection of element nodes of three parts of rubber joint to cohesive contact,considers the influence of pre-compression on the joint fatigue. By comparing actual picture and the results of finite element analysis, finally find out the control factors of fatigue damage. The main work of this paper includes the following five aspects:(1) According to the bonding strength of metal and rubber provided by the drawings, I will establish surface-based cohesive behavior model and ensure the parameters.(2) Further determine controlling factors of fatigue of rubber joint by analysising stress field, strain field and strain energy density field of the old structure.Apply quadratic stress initial damage and damage evolution criteria to describe stiffness degradation and debonding between interfaces(3) Applying2mm pre-compression on the diameter direction of new structure, considering the self-contact influence of rubber, to determine fatigue controlling factors of rubber joint and ensure pre-compression effect on fatigue life.(4) Establish viscoelastic constitutive relation of rubber, make it consistent with relaxation modulus expression of Abaqus software, and determine the viscoelastic parameters by comparison.(5) Based on viscoelastic model of rubber bush, analy the relationship between creep time and stiffness loss, determine the influence of pre-compression on creep stiffness loss rate,determine whether the stiffness loss will cause failure of joint.The results showed that:the strain is more sensitive to the fatigue damage of rubber than stress. normal strain show the fatigue failure of rubber better than maximum principal strain. For the new structure, pre-compression can alleviate the fatigue failure of rubber in a certain extent, improve the fatigue life of rubber joint. For the old structure, the maximum principal strain field can reflect the tackless behavior of interfaces, but quadratic stress initial damage and damage evolution criteria have more direct description of the interfacial stiffness degradation and debonding, it is more reasonable to determine the tackless behavior of metal rubber joint. From the viscoelastic analysis, pre-compression can reduce the stiffness loss rate, creep of joint does not cause stiffness failure.