Methods For Modeling And Parameters Identification Of Rubber Bushing

Rubber bushings as connecting parts of vehicle chassis and body and powertransmission system, have important influence on vehicle ride comfort and handling stabilitybecause of their super elasticity and nonlinear hysteresis characteristic. As a result of theintroduction of a large number of rubber bushing, the boundary constraint load even the hardpoint configuration changes must be provided to simulate the vehicle or assembly with multibody dynamics method or to design the reliability and durability of vehicle parts. It is obviousthat exploration and simulation of rubber bushing’mechanical properties are needed to be done.The viscoelastic unit of the existing bushing model doesn’t take account of the effect ofdifferent amplitude, and the existing bushing model is always used in low frequency simulation.When they are used in high frequency condition, their accuracy goes bad.The main goal of this paper is: by exploring the modeling form of each unit in therubber bushing model, building a new bushing model, which can take account of the effect ofdifferent amplitude and different frequency, and have a good result in high frequency simulation,so as to accurately simulate the boundary constraint load of the vehicle parts.The structure of the paper is as follows:Firstly, the rubber bushing modeling method is studied. Rubber bushing model isgenerally based on the superposition principle. Respectively modeling the elastic unit ofmain stiffness and viscoelastic unit of frequency dependent and elastoplastic unit of amplitudedependent, the combination of them is as the rubber bushing model. This paper mainly exploresthe modeling form of these three units. This paper compares the load response characteristicsof different model, and analysis the effect of the model parameters. The model established inthis paper uses a fractional derivative model to describe viscoelasticity, at the same time, theParameter of this unit is considered as a nonlinear correlation of amplitude. And thetransient friction model describing the dynamic and static friction switching is introduced in theelastoplastic model part.Exploring the dynamic and static characteristics of the rubber bushing with loading test. Arubber bushing from suspension system is chosen as the research object because of its typicalnonlinear hysteresis characteristics. Loading test is completed in the State Key Laboratory of Automotive Simulation and Control. Large amount of test data is obtained by designing static,spot and frequency sweep test conditions. Then the paper analyses the bushing dynamic andstatic characteristics exhibiting in loading test.Parameter identification methods of the rubber bushing model are mainly studied.Obtaining reliable parameter is the key to accurately simulate the boundary constraint load.With the data of rubber bushing loading test, rubber bushing model parameters are identifiedrespectively by using dynamic and static step identification method. Using static test data, theparameter of the elastic unit and elastoplastic unit are identified. This method obtains thedynamic parameters with the test data of frequency-domain dynamic stiffness anddamping angle. Using the sweep test data of different amplitude, the dynamic parameters ofviscoelastic unit are identified.The rubber bushing model established in this paper is verified by simulation.Displacement of time series from the frequency sweep test is as input. The simulation resultwhich has a good consistency compared with the experimental data proves the validity of themodel. Typical rubber bushing Kelvin-Voigt model and Berg model are chosen to compare withthe bushing model established in this paper. Using step identification method, the parametersof three model are identified. Then a simulation of spot test is done to compare with theexperimental data, which proves the accuracy of the three units model.