This paper presents an integrated validation strategy of the large scale MSC.Nastran Finite Element models of a body in white using a special software package for computational model updating. The strategy takes into account the complete process chain from model based test design, over modal testing, data evaluation, test/analysis correlation to computational model updating. By utilizing the given Finite Element model both measurement degrees of freedom and exciter positions are first virtually defined and then transferred onto the body in white. In order to keep uncertainties from the experimental investigations as small as possible and for generating an optimal data base for the following model validation thorough test planning and test execution is essential. For avoiding so called 'mass loading' effects the data acquisition is performed using a roving hammer excitation with fixed accelerometer positions. Besides the direct increase of the model quality, the computational model updating provides the additional opportunity to identify regions, where remodeling already yields an improvement of the model quality. The test/analysis correlation before and after the computational model updating as well as the remodeling exhibits a noticeable reduction of the frequency deviations along with an increase of the Modal Amplitude Coherence (MAC) values over a broad frequency range. These investigations are currently expanded towards attachment parts like doors as well as subassemblies in the frame of the cooperation 'work group 6.1.19 structure optimization and acoustics' of the German car industry. A first goal is to sufficiently represent the structural dynamics for having thorough basis for subsequent investigations on acoustic phenomena.
Experimental modal analysis and computational model updating of a car body in white
Experimentelle Modalanalyse und rechnerunterstützte Validierung des FEM-Modells einer Rohkarosserie
2004
14 Seiten, 10 Bilder, 9 Quellen
Conference paper
English
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