No abstract

This study addresses the dynamic behaviors of a bearing supporting structure composed of rubber O-rings. To develop an analytical method to predict the dynamic properties of the O-rings without using any dimension-dependent experimental data, the viscoelastic behaviors of the material were modeled with Maxwell-hyperelasticity proposed by the authors. The viscoelastic model was implemented using the finite element method (FEM), and a dynamic analysis was performed, the results of which were compared with the experimental data. The influences of the dimensions, frequency, squeeze, and surface condition on the dynamic properties of the O-rings were clarified, and independent design parameters were determined. The values and distributions of hydrostatic pressure, principal strain, and viscous dissipation energy were also discussed.

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.