Power flow estimation using pulse ESPI

Measurements performed using a double pulse ESPI (Electronic Speckle Pattern Interferometry) are used to estimate the power flow maps in a square plate excited harmonically. The pulse ESPI was equipped with one camera providing no information about the phase of the measured displacement field. A procedure based on the solution of a system of transcendental equations which corresponds to two measurements with a known time delay is used to determine the magnitude and phase. In order to spatially smooth the operational modes and reduce the noise spikes, a smoothing technique and a median filter are used, respectively. The active power flow is estimated for two frequencies. The reactive power flow due to the bending moments, twisting moments and shear forces are obtained separetely. A finite element model based on the theory of thin plates is used for qualitative comparison of the reactive power flow maps.