Next Article in Journal
Fire Control System Operation Status Assessment Based on Information Fusion: Case Study
Next Article in Special Issue
Numerical Simulation and Experimental Study of Fluid-Solid Coupling-Based Air-Coupled Ultrasonic Detection of Stomata Defect of Lithium-Ion Battery
Previous Article in Journal
UHF RFID Prototyping Platform for ISO 29167 Decryption Based on an SDR
Previous Article in Special Issue
Fully Noncontact Hybrid NDT for 3D Defect Reconstruction Using SAFT Algorithm and 2D Apodization Window
Open AccessArticle

Air-Coupled and Resonant Pulse-Echo Ultrasonic Technique

Instituto de Tecnologías Físicas y de la Información (ITEFI), Spanish National Research Council (CSIC), 28006 Madrid, Spain
Author to whom correspondence should be addressed.
Sensors 2019, 19(10), 2221;
Received: 15 April 2019 / Revised: 8 May 2019 / Accepted: 9 May 2019 / Published: 14 May 2019
An ultrasonic, resonant, pulse-echo, and air-coupled nondestructive testing (NDT) technique is presented. It is intended for components, with regular geometries where it is possible to excite resonant modes, made of materials that have a high acoustic impedance (Z) and low attenuation coefficient (α). Under these conditions, these resonances will present a very large quality factor (Q) and decay time (τ). This feature is used to avoid the dead zone, produced by the echo coming from the first wall, by receiving the resonant echo from the whole specimen over a longer period of time. This echo is analyzed in the frequency domain to determine specimen resonant frequency, which can be further used to determine either velocity or thickness. Using wideband air-coupled transducers, we tested the technique on plates (steel, aluminum, and silicone rubber) by exciting the mode of the first thickness. As expected, the higher the Z and the lower the α, the better the technique performed. Sensitivity to deviations of the angle of incidence away from normal (±2°) and the possibility to generate shear waves were also studied. Then, it was tested on steel cylindrical pipes that had different wall thicknesses and diameters. Finally, the use of this technique to generate C-Scan images of steel plates with different thicknesses was demonstrated. View Full-Text
Keywords: air-coupled ultrasound; ultrasonic NDT; air-coupled transducers; air-coupled pulse-echo; pipe NDT; pipe wall gauge air-coupled ultrasound; ultrasonic NDT; air-coupled transducers; air-coupled pulse-echo; pipe NDT; pipe wall gauge
Show Figures

Figure 1

MDPI and ACS Style

Álvarez-Arenas, T.G.; Camacho, J. Air-Coupled and Resonant Pulse-Echo Ultrasonic Technique. Sensors 2019, 19, 2221.

AMA Style

Álvarez-Arenas TG, Camacho J. Air-Coupled and Resonant Pulse-Echo Ultrasonic Technique. Sensors. 2019; 19(10):2221.

Chicago/Turabian Style

Álvarez-Arenas, Tomás G.; Camacho, Jorge. 2019. "Air-Coupled and Resonant Pulse-Echo Ultrasonic Technique" Sensors 19, no. 10: 2221.

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Search more from Scilit
Back to TopTop