A Study on the Effects of Local Added Masses on the Natural and the Sound Radiation Characteristics of Thin Plate Structures

As panel-like structures are widely used in industrial products such as high speed trains, automobiles, and ships, the effects of additional attachments (e.g. lumped mass, rib-stiffeners) to the panels on their dynamic/acoustic characteristics have been investigated analytically, numerically, experimentally or combining two or all the methods in the past decades. The present study focuses on highlighting the differences among local mass effects on the vibration and the radiation behaviour of flexible modes of the flat panel structures. A simple model comprising a local mass attached to a rectangular plate surface is set up, allowing us a deep insight into how the local mass affects the inherent mode parameters and the corresponding vibration and radiation characteristics of panel structures. The influential phenomena are first investigated analytically and then verified using FE-numerical simulations. The results show that: (1) the dynamic modal parameters of flat panel structures show different sensitivity to the values of the added mass and its locations; (2) the vibration and radiation characteristics of elastic modes with the same order can be affected in quite different degrees by the same local mass attachment; and (3) the modal acoustic interactions of thin plates can be significantly affected by the local mass attachments.