Chapter27 A Complex Power Approach to Characterise Joints in Experimental Dynamic Substructuring E. Barten, M.V. van der Seijs, and D. de Klerk Abstract The dynamic response of coupled structures is influenced by the joints connecting the individual substructures. The friction induced by the interfaces causes non-linear and damping-like effects, which need to be taken into account when applying Experimental Dynamic Substructuring techniques. This paper proposes a compliant interface model in the framework of substructuring, in order to account for the influence of jointed connections. Rather than modelling damping as a separate phenomenon, the proposed compliant interface model characterises (non-linear) damping as a function of the interface force and motion directly. As such the model fits into the Lagrange-Multiplier FBS method. In addition, the concept of complex power is adopted to characterise the effect of damping and isolate the contribution of the interface from the overall dissipation. The theory is illustrated with a test-case on a dedicated test structure. A successful attempt was made to identify damping parameters based on power dissipation of the structure. Keywords Frequency Based Substructuring • Experimental Dynamic Substructuring • Compliant interface • Complex power • Damping Nomenclature u; f; g Vector of displacements, external forces, internal forces uc; Vector of relative displacement at the interface, interface force intensity M; C; K Mass-, damping- and stiffness matrix of unassembled structure Mc; Cc; Kc Mass-, damping- and stiffness matrix of the compliant interface B; L Signed Boolean matrix, Boolean Localisation matrix Z; Y Dynamic stiffness, receptance Zc; Yc Dynamic stiffness, receptance of compliant interface Pe; Pi Excitation power, interface power Pd; Pk Dissipative power, exchange power DS Dynamic Substructuring LM-FBS Lagrange Multiplier Frequency Based Substructuring FRF Frequency Response Function DoF Degree of freedom FEM Finite Element Method E. Barten ( ) • M.V. van der Seijs • D. de Klerk Department of Precision and Microsystem Engineering, Section Engineering Dynamics, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft, The Netherlands e-mail: emielbarten@gmail.com; m.v.vanderseijs@tudelft.nl M. Allen et al. (eds.), Dynamics of Coupled Structures, Volume 1: Proceedings of the 32nd IMAC, A Conference and Exposition on Structural Dynamics, 2014, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-04501-6__27, © The Society for Experimental Mechanics, Inc. 2014 281
RkJQdWJsaXNoZXIy MTMzNzEzMQ==