Interior mode selection in the Craig Bampton reduction technique based on an energy approach
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Finite element analysis is adopted in several engineering fields as such structural dynamics and multibody system dynamics. Fine meshes are usually employed to guarantee model accuracy. As a consequence, models have typically very large dimensions, and hence they are difficult to handle and often prone to numerical ill conditioning. Model reduction techniques, such as the Craig Bampton method, can be extremely useful to minimize model dimensions. This paper introduces an effective ranking method for the selection of CB interior modes suitable for vibrating systems under single harmonic excitation. The goal is to keep model dimensions to a minimum while preserving system forced response accuracy. The ranking of the interior modes is carried out using coefficients based on energetic considerations and taking into account the frequency and the shape of the force exciting the system. The aforementioned coefficients provide a measure of the contribution of each interior mode to the computation of the mean mechanical energy stored by the system in a period of excitation. The method is then applied to the model of a vibratory feeder. The results shows that the proposed method provides a very effective selection of the most important interior modes and therefore allows outperforming current state-of-the-art techniques.