Experimental determination of flexural power flow in beams using a modified prony method

Analyzing standing waves and reactive vibration power is often not sufficient to solve vibroacoustic problems. Damping is a key factor in mechanical vibrations, and it is frequently the result of waves propagating from energy sources to energy sinks and boundaries. Structural power flow is a means of representing the wave propagation within a structure. The difficulties encountered in computing the power flow from measured data are mainly due to the sensitivity of the existing methods to measurement noise. Most existing techniques rely on a few measurements and a finite difference approximation of spatial derivatives, which is known to amplify noise. In this paper a new method is proposed to compute the flexural power flow in beams from measured transverse accelerations. The Prony method is used to estimate both the wavenumber and the flexural wave equation coefficients from overdetermined measured data. The method is modified to impose the known relations existing between the complex exponentials in the wave equation solution. The formulae relating the wave component parameters to the power flow are well known. Numerical simulation results and experimental results are shown to illustrate the proposed method. The method has the potential to treat different wave types superposed, as it is often the case in truss structures. (C) 1996 Academic Press Limited