Parameters identification of constitutive models of rubber bushing

Rubber bushing is used in vehicle suspension systems and plays important roles as connection, mounting, or vibration isolation. To study rubber bushings, one method is to acquire parameters of the constitutive models of rubber from tests of material sample, and to obtain stiffness curves by simulation. Generally, the low-cost uni-axial tension or compression test is used for this method. But parameters from these uni-axial tests are not accurate enough and only part of the properties is represented. To get more accurate parameters, other costly tests and special equipments will be needed. Another method is to directly test stiffness of rubber bushing parts in six loading directions. The stiffness can also be approximated by using empirical formulas with dimensions of bushings. This method simplifies the bushing model and is limited. A new approach is proposed in this paper. First, radial and axial stiffness tests of rubber bushing are conducted and stiffness curves are acquired. Then, the parameters of appropriate constitutive models of rubber bushing are approximated by using the test data. Here, adaptive response surface method and others optimization methods can be employed to find the parameters which best fit the constitutive equation. With parameters acquired above, the rotational stiffness curves are simulated and compared to test data. The example of simple rubber bushing shows that the proposed method is effective and efficient. Copyright © 2011 SAE International.