Modeling Nonlinear Bearing and Rubbing Phenomena in Rotor–Stator Contact Using Nonlinear Frequency Response Analysis

Rotor-to-stationary rub is a fault in rotating machinery that can lead to catastrophic failure of the machine. The current approach in the gas turbine industry is to model the rub event in a time-domain analysis and/or perform experimental validation using measured data analysis. Both approaches are time-consuming, resource-intensive, and not suitable for use in the design phase. An alternative is to use frequency response analysis, which provides a nonlinear response of the system as well as nonlinear forces at the rub location to improve the design across the entire range of operation. In recent times, significant improvements have been made to the nonlinear frequency response analysis capability in commercially available tools, enabling the analysis of large production models. In this paper, a Nelson-McVaugh rotor model with nonlinear bearings and nonlinear gap element with friction is analyzed to understand the contact behavior in a frequency domain analysis. A parametric study on friction coefficient, and different harmonic response combinations is also provided. Eliminating roadblocks to efficient analysis will provide a powerful tool at various design phases.