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.

Theoretical study of effect of the geometrical parameters on the dynamic properties of the elastic rings of an air journal bearing

“…They also concluded that both stiffness and damping coefficients increase when the ring thickness increases. [ 78 ] calculated using FEM and verified experimentally the dynamic coefficients of squeezed O-rings used to support high-speed bearings of high-speed turbo machinery. The concluded that the stiffness coefficient of the O-rings increases with frequency [ 12 ].…”

Flexible Support for Gas-Lubricated Bearing Bushings

“…A model using 1D beam elements as well as a 3D model using tetrahedral elements has been set up to determine the radial and tilting stiffness k r and k t . O-Rings, whose dynamic characteristics are highly dependent on the excitation frequency [11,18,19,20,21], the membrane measurement results suggest that the radial stiffness k r is independent of the excitation frequency f , which makes their use as a flexible support for HGJB bushings significantly easier and more predictable.…”

Identification of the Effect of Ultrasonic Friction Reduction in Metal-Elastomer Contacts Using a Two-Control-Loop Tribometer

“…While breakaway transients occur as a transition from sticking or pre-sliding to the sliding state due to the release of pre-stress between the contact opponents, dynamic friction behavior occurs while relative motion or sliding takes place at the macro-scale. When friction reduction in elastomer-metal coupled contacts is induced by ultrasonic vibrations, these two friction states are accompanied, besides material wear, with multi-frequency excited friction characteristics, such as variations of contact stiffness, variations of shear stress distribution [13] and local occurrences of glass transitions [14,15]. Thus, the experimental investigation of ultrasonic friction reduction requires individual identifications of these effects.…”