Master thesis and internship[BR]- Master's thesis : Virtual Shaker Testing: Modelling, vibration analysis, and experimental validation of an electrodynamic shaker model coupled to a test specimen[BR]- Integration Internship

Abstract

The aim of this master thesis is to develop a virtual shaker testing. It allows to predict coupling phenomena between a structure to be tested and the shaker.

The first objective is to model the shaker. To do so, a lumped parameter model is used. The shaker is modelled by three degrees of freedom: the vertical translations of the coil, the table and the body of the shaker. Taken from the literature, the equations of this model are written. They are then implemented in Simulink software. To simulate the dynamics of the shaker, the parameters of this model first need to be identified. A method is therefore developed to compute the mechanical and electrical model parameters. Simulations of shaker vibrations can finally be performed in Simulink. These simulations are validated by experimental vibration tests.

The second objective of this work is to couple the model of a specimen to the model of the shaker in order to simulate a complete shaker test. In a first time, the specimen is numerically synthesised by a finite element model. An experimental modal analysis is performed to validate the model of the specimen. When this model is validated, a superelement is extracted and is introduced in the Simulink shaker model. A complete test of the shaker/specimen assembly can finally be simulated. The simulations are compared with an experimental test. It is shown that the method gives satisfying results for a small shaker (for example a 445-N shaker) but is less conclusive for a large shaker (such as a 120-kN shaker). The second method consists in building an experimental model of the specimen. To do so, the frequency-based substructuring theory is used to create an experimental superelement. As for the first method, it is introduced in the Simulink shaker model and a complete test is simulated. This method gives similar results to the first one.