Energy Dissipation Associated with Gas‐Pumping in Structural Joints

Recent experimental work dealing with the vibratory energy dissipation of plates with beams riveted to them has indicated that the dominant damping mechanism is associated with “gas‐pumping” in the space between the plate and the beam. Based on this deduction a semiphenomenological theory is developed that predicts satisfactorily not only the order of magnitude of the loss factors, but also their dependence on frequency and on gas pressure. This theory attributes the damping to viscous forces associated with gas motion tangential to the plane of the plate, resulting from the relative flexural motion between the adjacent plate and beam surfaces.