Model reduction of rotor-foundation systems using the approximate invariant manifold method

This work presents a model reduction method suited for performing nonlinear dynamic analysis of high-dimensional rotor-foundation systems modeled by the finite element method. The approach consists in combining the component mode synthesis (CMS) method with the approximate invariant manifold method (AIMM), and allows the obtention of forced responses through the integration of a single pair of ordinary differential equations. The proposed approach is tested using two examples: a simple and a complex rotor-foundation system. In both cases, the nonlinearity comes from the fluid-film bearings. The results show that the method can provide a significant reduction in numerical cost while still retaining good accuracy when compared to direct time integrations. By means of the proposed method, the nonlinear dynamic analysis of high-dimensional rotor-foundation system becomes a feasible option.