Measurement-based determination of the irrotational part of the structural intensity by means of test functional series expansion

Abstract

The irrotational part of the structural intensity for flexural wave motion in plate-like structures is calculated from measurement data of kinematic quantities, such as out-of-plane velocities, by a new method that makes use of a test functional series expansion. The computation of the structural intensity and its irrotational part, which allows to effectively assess vibrational sources and sinks, is less sensitive to measurement noise as compared to standard approaches.

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

“…A low-pass filter is applied to the data in the wavenumber domain to attenuate the amplification of measurement noise. The combination of this spatial derivation with filtering was shown to be less susceptible to corrupted data, when compared to its finite-difference concept counterpart [3][4][5]8,26,27]. The low-pass filter developed by Li et al [28] is used in the present work.…”

“…The Eqs. (2)(3)(4)(5)(6)(7)(8)(9)(10)(11) were implemented as if the plate was homogeneous with respect to the thickness and stiffness, i.e., = 69 GPa and ℎ = 5 mm. The displacement fields' derivatives were carried out with a cut-off wavenumber equal to the ones used on the experimental data ( =315 rad/m) and the energy paths were estimated ( Figure A.3).…”

“…The main limitation of such an approach is that it alters the system's behavior due to the added mass of the transducer. Later, non-contact methods which do not add mass to the measured structure were used to detect surface motions, i.e., the Laser Doppler Vibrometry (LDV) [3][4][5][6], acoustic-holography [7], electronic speckle interferometry [8] or holographic interferometry [9]. These techniques are not only non-contact but also allow the measured displacement or velocity fields to be recorded with higher spatial resolution than the mentioned pioneering studies.…”

“…In turn, the spatial derivatives of the out-of-plane displacement fields provide the necessary inputs for the assessment of SI and the localization of sources and sinks. Many studies have already been carried out to estimate the energy flow in the form of vector fields or by calculating its divergence, which allows clear visualization of vector's dispersion or convergence [4,5,[11][12][13][14][15].…”

Structural intensity analysis of stepped thickness rectangular plates utilizing the finite element method

“…The energy transmission through a box-type structure built up by plates is considered by Chen et al [25], while Roozen at al. [26] used measured data of kinematic quantities to compute structural intensity and its irrotational part in plate-like structures. Very recently, Petrone et al [27] presented numerical and experimental analysis on structural intensity in orthotropic rectangular plates, investigating the effects of constraints, load conditions, damping, thickness and fibers orientation.…”