| Rubber isolators are widely used in automotive vibration isolation systems. In this paper, the static and dynamic properties of rubber isolators are investigated. The research objective of the study is to provide the design theory and calculation methods for developing rubber isolators. The contents of this dissertation are:1. The static properties of a rubber isolator are investigated through experiment and calculation. The experimental procedures, which are used to test the static properties of a rubber isolator and hyperelasticity of rubber material, are discussed. Uniaxial tension test, biaxial tension test and planar tension test to obtain the stress versus strain of rubber specimens are conducted. Furthermore, the data processing methods for estimating constitutive parameters of hyperelastic model are discussed, and the accuracy of various hyperelastic models for fitting the test data is compared.The static force versus displacement of a powertrain mount (rubber isolator) is calculated. The accuracies, using various hyperelastic models to calculate the static properties of a rubber isolator, are compared. Moreover, the effects including Mullin effect, bulk deformation, and types of hyperelastic material test on predicting the static properties of a rubber isolator are investigated by experimental and calculation approach. The modeling and calculation methods presented in the study are valuable for rubber isolators' development and lay a foundation for investigating into dynamic properties of a rubber isolator in this paper.2. An approach for calculating the dynamic properties of a rubber isolator is proposed, which can be used to calculate the dynamic properties of a rubber isolator under displacement excitations with constant amplitudes. A hyperelastic-viscoelastic model is established to describe the frequency-dependency of dynamic properties of a rubber isolator. Meanwhile, the experimental method for obtaining the parameters of rubber material in the viscoelastic model is presented. The effect of static rate error on the calculation of dynamic properties of a rubber isolator is discussed and eliminated by rate correction method. Taking a suspension bushing (a kind of rubber isolators) as a studying example, the dynamic and static properties of the rubber bushing are calculated and compared with the experiment. The proposed calculation method plays a guiding role in designing structure and selecting compound for a rubber isolator, and lays a foundation for further investigation of the dynamic properties of a rubber isolator.3. A visco-plastic constitutive model by superimposing the constitutive model in commercial FE (Finite Element) code is proposed, and it is used to model amplitude dependency of the dynamic properties of a rubber isolator. The simple shear experiment for the rubber specimen is used to identify the parameters of the proposed model.An approach named mesh-superimposition approach by superimposing FE mesh of the hyperelastic-viscoelastic model and elastic-plastic models is presented to calculate the dynamic properties of a rubber isolator. Meanwhile, another approach named result-superimposition approach, superimposing the results calculated by hyperelastic-viscoelastic FE model and elastic-plastic FE models respectively, is used to calculate the dynamic properties of a rubber isolator. The results calculated by mesh-superimposition approach and result-superimposition approach are compared and discussed. It is indicated that the two proposed approaches can be used in predicting the dynamic properties of a rubber isolator.4. An approach, based on a model including amplitude-dependency of the dynamic properties of rubber material, is proposed to calculate the dynamic properties of a hydrobush (hydraulic rubber isolator).The dynamic properties of a hydrobush are measured. The Fluid-Structure Interactive (FSI) model of a hydrobush is described in details. The dynamic properties of main rubber element (MRE) of a hydrobush calculated by hyperelastic-viscoelastic model and visco-plastic model respectively are compared. Furthermore, the visco-plastic model is applied in the analysis for the dynamic properties of a hydrobush with FSI method, and the calculated results are compared with the hyperelastic-viscoelastic model. The proposed approach for calculating the dynamic properties of hydrobush will help to improve the efficiency in product design.5. A method for modeling the dynamic properties of a rubber isolator is proposed by superimposing hyperelastic model, fractional derivative model and frictional model.The methods for estimating the model parameters are illustrated in details. The calculated dynamic properties of a rubber isolator with the proposed model and the identified model parameters are compared with the experiments. Moreover, the time domain response is measured for a mass in a single degree of freedom (SDOF) system with a rubber isolator under various displacement excitations. The methods for estimating the response of a mass are established, the calculated response of an actual SDOF system with the proposed model and solution method are compared with the experiments. The proposed modeling method for dynamic properties of a rubber isolator can be used to model the rubber isolators in dynamic system.
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