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Shock and Vibration
Volume 17, Issue 4-5, Pages 359-371
http://dx.doi.org/10.3233/SAV-2010-0532

Damping Prediction of Structures with Bolted Joints

Lothar Gaul and Jens Becker

Institute of Applied and Experimental Mechanics, University of Stuttgart, Pfaffenwaldring 9, 70550 Stuttgart, Germany

Received 17 June 2010; Accepted 17 June 2010

Copyright © 2010 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Friction in joints significantly contributes to the observed overall damping of mechanical structures. Especially if the material damping is low, the frictional effects in joints and clamping boundary conditions dominate the structural damping. The damping and the stiffness of the structure are nonlinear functions of the system states and consequently of the excitation signal and amplitude. If these nonlinear effects should be incorporated in the design process, transient simulations must be employed in order to predict and analyze the damping for a given excitation, though they need excessive computation power due to the nonlinear constitutive laws and the high contact stiffnesses.

As one approach to alleviate transient simulations, the application of component mode synthesis (CMS) methods to structures with friction is investigated exploiting the linearity of the jointed substructures. The friction and the nonlinear normal contact is modeled by constitutive laws that are implemented in node-to-node finite elements. The necessary considerations for accurate damping prediction by the reduced models, the accuracy and the computational times for transient simulations are discussed. The developed model reduction techniques allow a strong reduction of the computation time which in turn makes it a promising tool for model updating and predictive parameter studies. As an application example, a beam-like structure with attached friction damper is investigated in simulations and the obtained numerical results after model updating are compared to experiments.