Mechanical joints such as bolted and spot welded joints are widely used to join plate structures. The existence of contactinterface in the joint increases the vibration damping in the structure because the energy dissipation due to friction occurs atthe interface. In this paper, we propose a procedure for calculating the energy dissipation at the interface using finite elementanalysis to estimate the damping for the fundamental and the higher modes. We use the static contact analysis instead of thedynamic contact analysis to reduce computational effort and use the mode shapes of linear FE model of the joined platestructure as the forced displacement in the static contact analysis. This enables us to obtain the energy dissipation dependingon the mode shape for each mode. To improve the calculation accuracy of the energy dissipation, we apply a surface load onthe overlap (interface) region and find the necessary value of surface load. To validate the proposed procedure, the modaldamping ratios estimated from the dissipated energy are compared with the measured damping ratios. The results show thatthe proposed procedure enables to accurately estimate the energy dissipation of the joined plate structure. The necessarysurface load increases with increasing mode number and varies almost proportionally with the square of the angularfrequency.
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