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

摘要

In flexible multibody dynamics, body-level model reduction is typically used to decreasethe computational load of a simulation. Body-level model reduction is generally performedby means of Component Mode Synthesis. This offers an acceptable solution for manyapplications, but does not result in significant model reduction for systems with moving connectionpoints, 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 isachieved 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 ischosen configuration-dependent in such a way that the system dynamics are optimally describedwith a minimal number of degrees of freedom. Moving connection points do not pose a problemto the proposed model reduction methodology. The complexity of simulation of the reducedmodel equations is estimated. The applicability to systems with moving connection points ishighlighted. In a numerical experiment, simulation results for the original model equationsare compared with simulation results for the model equations obtained after model reduction,showing a good match. The approximation errors resulting from the model reduction techniquesare investigated by comparing results for different mode sets. The mode set affects theapproximation error similarly as it does in linear modal synthesis.