ACOUSTIC RADIATION DAMPING OF FLAT RECTANGULAR-PLATES SUBJECTED TO SUBSONIC FLOWS .2. COMPOSITE

The acoustic radiation damping for various laminated composite and alu minum plates subjected to a uniform, subsonic, and steady flow has bee n predicted. The predictions are based on the linear equations of moti on of a flat plate. The fluid loading is characterized as the perturba tion pressure derived from the linearized Bernoulli and continuity equ ations of fluid mechanics. Parameters varied in the analysis include M ach number and plate material properties and ply lay-up. Results show that the fluid loading can significantly affect realistic plate respon ses. Universal curves are presented where the acoustic radiation dampi ng normalized by the mass ratio is a smooth function of the reduced fr equency. A separate curve was required for each Mach number and plate aspect ratio. Generally, graphite/epoxy and carbon/carbon plates have higher acoustic radiation damping values than similar aluminum plates, except near plate divergence conditions resulting from aeroelastic in stability. In addition, acoustic radiation damping values can be great er than or equal to the structural damping ratio component (assumed as 0.01) for the higher Mach numbers.