Structural intensity analysis of flat plates based on digital stroboscopic holography measurements

Abstract

The analysis of structural intensity vector fields has shown to be a practical approach to characterize the energy flow in plate-like structures and to localize regions of injected or absorbed power. Such an analysis is performed by differentiating measured velocity or displacement fields of a sample. The quality of such a study strongly depends on the spatial resolution of the deformation data and its signal-to-noise ratio. The digital stroboscopic holography concept is presented in this work and used as a tool to record such deformations on a flat plate, which is in direct contact with a shaker and a damper. The current setup could provide the recording of displacement fields at a high spatial resolution showing little corruption by noise. These conditions permitted the measurement of deformation patterns containing short wavelengths, which were later used as inputs for the structural intensity analysis. By calculating the spatial derivatives of several out-of-plane displacement fields, the energy flowing through the plate was estimated and the position of the external devices (shaker and damper) could be identified by locating regions of the energy dispersion or convergence. The location of these specific regions was made even clearer by calculating the divergence of the energy flow.

Structural intensity assessment on shells via a finite element approximation

“…Examples of reported methods to analyze the vibrational energy are the laser Doppler vibrometry (Arruda and Mas, 1998;Morikawa et al, 1996;Pascal et al, 2002Pascal et al, , 2006Roozen et al, 2015;Schmidt, 2009;Vuye, 2011;Zhang and Mann III, 1996), acousticholography (Pascal et al, 1990;Saijyou, 2007), electronic speckle interferometry (Eck and Walsh, 2012), holographic interferometry (Pascal et al, 1996) and digital stroboscopic holography (Pires et al, 2018).…”