Influence of nonlinearities upon a virtual closed-loop vibration controller: Application to a simplified model of the Galileo spacecraft

Abstract

LMS Samtech has developed a dll file reproducing the behaviour of the Simcenter Testlab control system so as to integrate it into its finite element solver, Samcef. This virtual controller has then been validated with the Galileo spacecraft. To this purpose, experimental tests on the physical structure have been performed by ArianeGroup using the actual Simcenter Testlab software and replicated into Samcef integrated environment using very simplified linear models of Galileo and the shaker. The conclusion is that the dll replicates perfectly the behaviour of the actual controller provided that the coupled structure remains linear. On the other hand, for some test cases, multiple harmonics of the excitation frequency were detected in the time responses of the system but their origin has not been identified yet. In this project, these are assumed to originate from the activation of a structural nonlinearity at the interface between Galileo and the shaker. A nonlinear restoring force law is then integrated into the mechanical model and test simulations are performed so as to find harmonics as those detected experimentally