The Study On Mullins Induced Anisotropic And Multi-directional Stiffness Analysis Of Rubber Elastic Components

In order to rationally improve the effect of reducing vibration noise and ensure the ride comfort of railway vehicles, the design of the car body and the bogie used a lot of rubber elastic damping components. The rigidity of rubber elastic components is a very important factor to driver comfort and safety of railway vehicles. So accurately calculating and effectively predicting the stiffness of rubber elastic components in the phase of design and development were the very important aspects. But compare a lot of finite element simulation calculation value of the past with the experimental results it can be seen that finite element analysis value of using the present method for rubber components multi-directional stiffness(especially the horizontal stiffness value) was much different. The cause of the big difference is due that in the simulation analysis Mullins of rubber material softening effect and Mullins induced anisotropy were not considered. In order to make true of the engineering application of the finite element analysis to simulate the softening effect of Mullins and induced anisotropy, this paper based on the experiment to study Mullins softening induced anisotropy, put forward a new rubber elastic element simulation analysis methods of multi-directional stiffness under the condition of thinking of the rubber materials Mullins induced anisotropy.First of all, deeply studied basic properties and generating mechanism of the rubber materials Mullins softening effect and its’ induced anisotropy. At present some commercial software using pseudo-elastic theory to the simulation calculation of Mullins softening effect, but the constitutive model reckoned Mullins softening effect just be approximately regarded as a kind of isotropic softening, without considering the effect of Mullins softening’s inhomogeneity(namely Mullins softening induced anisotropy).Second, because the pseudo-elastic constitutive theory has some defects simulation, in order to fully considered Mullins softening induced anisotropy in the finite element simulation calculation for meeting the needs of the engineering need, this paper creatively conduct multiple load levels two-way tensile/tensile loading history specimens experiments to research the impact of Mullins softening induced anisotropy on the properties of rubber materials axial tensile; Also carried on the multiple load levels of two-way tensile/shear loading history specimens on the experiments to study Mullins softening induced anisotropy effect on the properties of the rubber material shear after axial tensile. Based in the hysteresis loops of two kinds of two-way load history experiments’ every different load level, it was proved that Mullins softening induced anisotropy had different effects on the two direction stiffness of rubber. And the mean residual sum of squares is used as a reference to analyze the change rule of influence degree.Then, based on the pseudo-elastic constitutive theory, using the rubber two-way load history the experiments data, using ABAQUS software bring constitutive parameters fitting tool, respectively fits the rubber material vertical softening parameters and horizontal softening parameters. Through two groups of softening parameters, quantitative analysis rubber materials Mullins softening induced anisotropy in the different types of load and different load levels. On this basis, innovative proposed the simulation analysis method of the multi-directional bearing rubber elastic components’ multi-directional stiffness. This paper, taking a tapered air spring auxiliary spring’s multi-directional stiffness as the simulation analysis of actual examples, in the process of analysis, using the grid drawing technology innovation make the vertical load and horizontal load divide into two step analysis, so in each analysis step respectively calculate the vertical stiffness and horizontal stiffness, to simulate the impact of Mullins soften induced anisotropy. Using the mean sum of squared residuals, compare the stiffness curve of finite element simulation with auxiliary spring experimental stiffness curve, it is verified that the method of multi-directional stiffness simulation analysis had good practicability and high accuracy.