How membrane loads influence the modal damping of flexural structures

This paper considers the transverse vibration of flexural structures subjected to preloads that are tangent to the structural midplane; the effects of such membrane loads on the damping of the structural vibration modes are of particular interest. The theory developed indicates that tensile loads increase the natural frequencies of vibration (as is well known), but decrease the modal damping; for beams, the effect on damping is stronger than the effect on frequency. Conversely, compressive loads decrease the natural frequencies and increase the modal damping. These conclusions are consistent for various models of material damping. Available experimental data show good agreement with theory.