Dynamic Analysis of a Rotor Supported on Ball Bearings with Waviness and Centralizing Springs and Squeeze Film Dampers

Squeeze film dampers (SFDs) are often used in machines with high rotational speed to reduce nonperiodic behavior by creating external damping. There are some structural parameters which are of great importance in designing these systems, such as oil film thickness and inner race mass of SFD. Moreover, there is a crucial parameter associated with manufacturing process, under the title of waviness. Geometric imperfections are often called waviness if its wavelength is much longer than Hertzian contact width. In this paper, a system of a flexible rotor and two ball bearings with squeeze film dampers and centralizing springs and also consideration of waviness has been modeled and solved by a numerical integration method to investigate the system dynamic response. Results show that by increasing the number of wave lobes, non-periodic and chaotic behavior increases. This reveals the importance of manufacturing accuracy and necessity of taking this term into account in simulations. Moreover, by changing the oil film thickness, it is revealed that there is an optimal value for this parameter to provide maximum damping. In addition, with increasing the inner race mass of SFD, the disc displacement amplitude increases. This reveals the importance of utilizing light materials in manufacturing the SFDs.