A Study on the Determination of Material Coefficients of Rubber Materials for Vehicle Secondary Suspension

The air spring in a railway operating environment to perform an appropriate function, it is necessary to have a design that satisfies the target stiffness. However, mechanical properties testing of rubber parts causes problems such as cost and time. In this paper, a material to satisfy the target stiffness of an air spring was presented through an analytical method. Air springs require an optimal design that satisfies the design target stiffness through nonlinear finite element analysis. The material constant of Shore 45A natural rubber was obtained through the equi-biaxial displacement-controlled test. Nonlinear finite element analysis was performed using ABAQUS to determine the material constant, and the optimal design was performed with I-SIGHT software. As a result of minimizing the relative error of vertical and lateral stiffness with a comparison algorithm, it was confirmed that material constants C10, C20, and C30 satisfying the target stiffness were obtained. A uniaxial tensile test was performed on Shore 65A natural rubber specimens. It was confirmed that a correlation coefficient of about 0.984 was obtained from the stress-strain curve between this test result and the determined material constant. From this result, it is suggested that Shore 65A natural rubber can be used as a material that can satisfy the target stiffness of the air spring.