Quantitative validation of an air-coupled ultrasonic probe model by Interferometric laser tomography

Abstract

The present paper describes the quantitative validation of a finite element (FE) model of the ultrasound beam generated by an air coupled non-contact ultrasound transducer. The model boundary conditions are given by vibration velocities measured by laser vibrometry on the probe membrane. The proposed validation method is based on the comparison between the simulated 3D pressure field and the pressure data measured with interferometric laser tomography technique. The model details and the experimental techniques are described in paper. The analysis of results shows the effectiveness of the proposed approach and the possibility to quantitatively assess and predict the generated acoustic pressure field, with maximum discrepancies in the order of 20% due to uncertainty effects. This step is important for determining in complex problems the real applicability of air-coupled probes and for the simulation of the whole inspection procedure, also when the component is designed, so as to virtually verify its inspectability.

Calculation of Volumetric Sound Field of Pulsed Air-Coupled Ultrasound Transducers Based on Single-Plane Measurements

“…Numerical methods are used to model and validate the influence of transducer material designs in excited ACU pressure fields, the interaction of ACU pressure fields with light sources, or the propagation of excited ACU beams in solid objects for NDE, among others. Popular methods are the finite element method (FEM) [17,[21][22][23] and finite-difference timedomain analysis (FDTD) [24,25]. While these methods are very flexible, they require a discretization of the full wave propagation domain and discretization steps h of at least one order of magnitude smaller than the wavelength , with typically h< /20.…”

A simple method for quantitative imaging of 2D acoustic fields using refracto-vibrometry

“…The calculation of instantaneous sound pressure using light intensity measurements has been shown to be sensitive and accurate [4]. The use of laser Doppler vibrometry to measure pressure fluctuations has received significant attention [5][6][7][8][9][10][11][12], including tomographic 3D field reconstruction [13][14][15][16][17]. Previous research has shown that quantified sound field visualisation is possible but the implementation is relatively complex.…”