| Hydraulic bushing (HB) is a new kind of vibration isolator for automotive chassis system. It consists of fluid damping mechanism based on the structure of rubber bushing. The dynamic characteristics of hydraulic bushing greatly satisfy the vibration-isolation requirements of vehicle and improve the vehicle’s driving stability and riding comfort. Another advantage of hydraulic bushing is light and convenient installation. The domestic equipment manufactures have not mastered the design ability and the application of HB. The systematic research on the design theory and technology of hydraulic bushing is very necessary. For these purposes, the main research work is as follows:1. The static and dynamic characteristics of hydraulic bushing are thoroughly tested. The test method and data processing technique for mechanical properties of HB are discussed. The static stiffness of hydraulic bushings is compared with that of rubber bushing. The results show that the axial and radial static stiffness of hydraulic bushing are greater than that of the rubber bushing. The influences of excitation amplitude and frequency on the dynamic performances of hydraulic bushing are investigated.The stress-strain curves under different strain state are obtained based on the rubber material experiment. Three kinds of hyperelastic constitutive model used in FEM are analyzed. The least squares are applied to identify the constitutive model parameters. The constitutive model and model parameters with the minimum fitting errors are selected to describe the rubber material in FEA. This is the foundation for the further calculation of dynamic properties of hydraulic bushing.2. The lumped parameter (LP) models for axial and radial damping HB with single inertia track are proposed. The dynamic stiffness, loss angle and the peak frequency of hydro-bushing’s loss angle are obtained from the LP model. Emphasis is placed on the identification of the system parameters of the LP model for HB with single inertia track. The calculated dynamic performances of HB are compared favorably with the experimental data, which validates the proposed models. The influences of lumped parameters on the dynamic characteristics of HB are analyzed. The lumped parameter models for HB with double inertia tracks are established. With the increase of the number of inertia tracks, the peak frequency is backward moved. The analytical methods and conclusions are instructive for the design and the tuning of performance of the HB.3. An efficient identification method for lumped parameters is proposed, and does not depend on the experimental sample. Radial damping HB is the object, which is widely used as vibration isolator in the vehicle chassis system. Two-way fluid-structure interaction (FSI) nonlinear finite element analysis (FEA) technique is used to identify the main parameters of the LP model, such as the radial dynamic stiffness of the rubber spring, the radial damping of the rubber spring, the volumetric stiffness of the chamber, the equivalent piston area, the inertia and the resistance of the fluid in the inertia track. Comparing the calculated results with the numerical prediction results, the feasibility and accuracy of the FEA method was confirmed. The method proposed in this paper can ensure high quality and low cost in hydraulic bushing development.4. The two-way coupled FSI and FEA model for simulation of HB is developed, which can be used to simulate the static and dynamic performances of the HB with only stress versus strain relations of the rubber materials, the fluid physical parameters and the HB sizes. The dynamic fluid pressure and the velocity in the chambers and the inertia track of HB are calculated under different excitation conditions in order to deeply understand the damping mechanism. |
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