A Three-dimensional, Multi-step Substructure Coupling Method Based on Frequency Response Functions with Control of the Statistical Measurement Error

摘要

To obtain exact results by modal substructure coupling, it is necessary to use a high number of substructure modes, which cannot be identified by measurements. Therefore a nonparametric coupling method based on measured FRFs has been developed where the influence of higher modes is not neglected during the process of identification. Because the coupling is performed as step by step modification, it is possible to include all kinds of linear constraints analytically. Tensorial transformation of the FRF matrix enables three-dimensional coupling. The influence of statistic measurement errors, which affect especially the coupling of linear dependent degrees of freedom, can be controlled by the Gaussian law of error propagation. The method has been verified by coupling real plate structures with rigid connections. Both analytical and measured FRFs have been used as data basis. The results will be compared with regard to numerical difficulties.