ENERGY-FLOW PREDICTIONS IN A STRUCTURE OF RIGIDLY JOINED BEAMS USING RECEPTANCE THEORY

A method for evaluating the energy flows in a general network of beams, based on receptance theory, is presented. The behaviour of the global structure is predicted from the Green functions of the individual uncoupled beams, evaluated as summations over their mode shapes. This permits analysis of structures having localized properties or those where the modal information is derived numerically (e.g., by the use of finite element analysis). The method is implemented as a computer program and aspects of numerical problems regarding Green function convergence and the extraction of higher modes are discussed. In the second half of the paper, a cantilever structure of 16 beams with eight joints is subjected to point harmonic forcing at a joint. The velocity responses at a joint remote from the point of forcing are compared against those from a finite element model and good agreement is obtained. The time and frequency averaged energy levels of all the beams in the structure are then studied under conditions of localized damping on different regions of the structure, and also for changes in geometry. (C) 1995 Academic Press Limited