Mobilities and impedances of structures. Part 2: Compendium of point mobilities of infinite structures.
Abstract:This Item is concerned with point mobilities of infinite structures, such as beams, plates and cylinders. It is a sequel to ESDU 04009, which is a compendium of the point mobilities of finite structures. Point mobilities of infinite structures are directly related to the modal density of the equivalent finite structures. As structures at high frequencies may approximate to infinite structures, the Item is applicable to Statistical Energy Analysis. The information on point mobilities is mostly provided in the form of tables that list the mobilities and other data, such as the velocity field, the wavenumber and the modal density. Point mobilities are considered for structures which include rods with one-dimensional longitudinal and torsional wave motion, beams with normal force and moment excitation, thin isotropic and orthotropic plates with normal force excitation, rings and cylinders. In the case of a plate the force or moment has to be applied through a small, rigid disc, otherwise the stresses at the point of application are infinite. The point moment mobility for a plate depends on the radius of the disc. Some systems involve two types of wave motion, for example, bending and shear waves occur in thick plates. Other structures involving two wave systems, all included in the tables, include thick plates, plates with in-force excitation, plates stiffened by a beam and a ring-stiffened cylinder.
|Data Item ESDU 04010|