Calculation of high-frequency dynamic properties of squeezed O-ring for bearing support

Abstract

Determination and prediction of the dynamic properties of an O-ring for bearing support were performed. Utilizing O-rings as supporters of bearing is a promising way to suppress severe vibrations such as resonance and self-excited whirl experienced in high-speed turbo machinery. However, analytical prediction of the dynamic properties of O-rings has not been very successful so far because of its non-linear dependence on many parameters. In this study, focusing on the incompressibility of rubber materials, the isochoric shear viscoelasticity of an O-ring material was measured for high frequencies of up to 1 kHz. In measuring the viscoelasticity, a testing method developed by the authors was used. This method enables obtaining high-frequency shear viscoelasticity directly without assuming the temperature-frequency superposition principle. The obtained dynamic shear properties were modeled as functions of the frequency and hydrostatic pressure. Finite element models of squeezed O-rings were constructed with the material model assuming uniform property distribution, and dynamic analyses were conducted. The dynamic properties of O-rings were determined from the time-series data for the applied force and displacement. The data agreed with the experimental results of an actual O-ring. It was found that the dynamic properties of rubber components can be analytically predicted by considering the frequency and hydrostatic pressure dependence on the viscoelasticity.