Model reduction of flexible multibody systems

Abstract

Numerical simulations are essential to determine the characteristics, performance and structural integrity of mechanisms and robots. With increasingly higher demands on the specifications of such devices, the demands on the accuracy of the numerical models increases as well. Increasing the complexity of the models, inherently increases the computational time of the simulations. Model reduction techniques can offer a reduction of the simulation time, while maintaining sufficient accuracy. In this work, the modelling of flexible multibody systems is considered. The starting point is a numerical approach based on non-linear finite elements such as beams, trusses and hinges. In particular the spatial beam element has proven to offer a numerical efficient analysis of mechanisms that consist of beam-like components. However, for systems with complex-shaped parts, or for systems composed of a rather large number of beams, the dimensionality of the model increases. Hence, two types of model reduction techniques are investigated for the efficient and accurate modelling of such flexible multibody systems. The first type deals with the efficient and accurate modelling of individual components that may be flexible and have a complex geometry. This is referred to as component model reduction. The second type attempts to reduce a complete non-linear multibody system and can therefore be referred to as a system model reduction approach. Both methods are demonstrated by modelling a largestroke two degree of freedom compliant positioning mechanism.