摘要：Vibrations of elastic plate and compressible fluid are investigated. Compressibility of the fluid influences eigenmodes and to some degree eigenfrequencies also, while density of the fluid eigenfrequencies changes more than eigenmodes. Calculations of steel plate vibrations in water and wood plate vibrations in air are presented, influence of the water and the air compressibility discussed. Interaction of plate eigenmodes in vacuum is represented by hydrodynamic matrix, entries of which depend on sound wave speed in fluid. Eigenmodes of the plate in vacuum and eigenmodes in incompressible fluid can be applied as base functions of the investigation, but the set of eigenmodes of the plate in compressible fluid does not form a set of complete orthogonal base functions.
