A system-level model reduction technique for efficient simulation of flexible multibody dynamics

In flexible multibody dynamics, body-level model reduction is typically used to decrease the computational load of a simulation. Body-level model reduction is generally performed by means of Component Mode Synthesis. This offers an acceptable solution for many applications, but does not result in significant model reduction for systems with moving connection points, e.g. due to a flexible sliding joint. In this research, Global Modal Parametrization, a model reduction technique initially proposed for real-time control of flexible mechanisms, is further developed to speed up simulation of multibody systems. The reduction is achieved by a system-level modal description, as opposed to the classic body-level modal description. As the dynamics is configuration-dependent, the system-level modal description is chosen configuration-dependent in such a way that the system dynamics are optimally described with a minimal number of degrees of freedom. Moving connection points do not pose a problem to the proposed model reduction methodology. The complexity of simulation of the reduced model equations is estimated. The applicability to systems with moving connection points is highlighted. In a numerical experiment, simulation results for the original model equations are compared with simulation results for the model equations obtained after model reduction, showing a good match. The approximation errors resulting from the model reduction techniques are investigated by comparing results for different mode sets. The mode set affects the approximation error similarly as it does in linear modal synthesis