Co 0 CO AIR FORCE FLIGHT DYNAMICS LABORATORY 0 RESEARCH AND TECHNOLOGY DIVISION AIR FORCE SYSTEMS COMMAND 0 WRIGHT-PATTERSON AIR FORCE BASE, OHIO ABSTRACT A largely experimental study is described, which indicates that dissipation of vibratory)energy at multi-point-fastened (bolted, riveted, spot-welded) joints connecting panels to stiffeners or to other panels, at frequencies considerably above the panel fundamental, is primarily due to the "pumping" of air produced as adjacent surfaces

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... fasteners move away from and toward each other. Heckl's absorption coefficient concept (J. Acoust. Soc. Am. 34, 803-808, June 1962) is shown to apply to the aforementioned joint types, and it is demonstrated that the joint absorption coefficient is a function of the ratio of fastener spacing to plate flexural wavelength. Based on these findings and on empirical data, an approach is developed for estimating the damping of panels with joints.