EXPERIMENTAL-DETERMINATION OF FLEXURAL POWER-FLOW IN BEAMS USING A MODIFIED PRONY METHOD

Analyzing standing waves and reactive vibration power is often not suf ficient to solve vibroacoustic problems. Damping is a key factor in me chanical vibrations, and it is frequently the result of waves propagat ing from energy sources to energy sinks and boundaries. Structural pow er flow is a means of representing the wave propagation within a struc ture. The difficulties encountered in computing the power flow from me asured data are mainly due to the sensitivity of the existing methods to measurement noise. Most existing techniques rely on a few measureme nts and a finite difference approximation of spatial derivatives, whic h is known to amplify noise. In this paper a new method is proposed to compute the flexural power flow in beams from measured transverse acc elerations. The Prony method is used to estimate both the wavenumber a nd the flexural wave equation coefficients from overdetermined measure d data. The method is modified to impose the known relations existing between the complex exponentials in the wave equation solution. The fo rmulae relating the wave component parameters to the power flow are we ll known. Numerical simulation results and experimental results are sh own to illustrate the proposed method. The method has the potential to treat different wave types superposed, as it is often the case in tru ss structures. (C) 1996 Academic Press Limited