High Accuracy Model Establishing And Applying Of Axial Symmetry Rubber Bushing

Rubber bushings can be found in all vehicle suspension systems. The suspension components are connected to each other, to the sub-frame, and to the body structure via rubber bushings. They are a key element in designing desired quasi-static and dynamic behavior of suspension systems.Multi-body simulations (MBS) of complete vehicles or subsystems are performed on a daily basis in the automotive industry. To achieve a high level of confidence in the MBS simulations, accurate component models of rubber bushings are crucial. The basic bushing model in ADAMS is simple and lacks frequency and amplitude dependence. So it is of greatest value to research and develop more advanced rubber bushing models.Under this background, there are many scholars and experts doing research about the property of the bushing model. And the achievements are great. Though absorbing and using these fruits, adopting the dynamics of multi-body system theory and making use of the ADAMS'user subroutine, this paper applied the new rubber bushing model into the multi-body system simulation by treating the bushing forces as massless external forces. The main content as follows:First of all, this paper analyzed the dynamic property of the rubber bushing and found the factors that influence the dynamic property of the rubber bushing. Then the development of the rubber bushing model is introduced. Based on theseanalyses, through compared to theoretic bushing models that have been put forward, this paper adopted the elastic viscoelastic elastoplastic model as its theoretic model. And then based on the actual framework of the rubber bushing, the whole bushing is divided into two rigid parts: outside steel circle and inside steel circle. They are connected with the equivalent elastic viscoelastic elastopastic model. The new rubber bushing model is built. At last, the theoretic dynamic stiffness and damping of bushing model are obtained via analytical approximation.In order to verify the frequency and amplitude influence on the property of bushing model, abundant experiments are performed, including static and dynamic experiments. The clamp'design and the control on experimental condition are introduced in detail for getting accurate experimental data in this paper. The experimental data shows: the bushing's dynamic stiffness and phase angle decrease with increasing amplitude when the frequency is fixed, and the bushing's dynamic stiffness and phase angle increase with increasing frequency when the amplitude is certain. And this also verifies that the theoretic rubber bushing model adopted in this paper is right from one aspect.In order to get model parameters from experimental data, a fitting procedure method is adopted. So an error function is needed. This function expresses the sum of the relative error of the component model compared to the experimental data. The whole fitting procedure method is divided into two parts: analytical part and numerical part because of balancing the calculation efficiency and the accuracy of the model parameters. The fitting procedure needs initial parameter values for the first error estimation. These initial values must be close enough to the best fit solution, otherwise the best fit will never be found. Estimations of the initial values are made using the experimental test results. Then adopting the fmincon algorithm provided by the tool-box in Matlab, a group of parameters was found to minimize the error function. This group of parameters was the bushing model's parameters.At last, in order to validate the new bushing model's rationality and validity, a right-front suspension system is built. Then through making use of the ADAMS'GFOSUB user subroutine to edit the bushing forces'properties, the new type of bushing model is built. The application of the new bushing model into the ADAMS is achieved via compiling and linking the subroutine. Simulation is performed separately with ADAMS'bushing model and the new bushing model. By compared to the different results of simulation, the appraisal of the new rubber bushing model is given.