Results 221 to 230 of about 20,357 (252)

Graded piezocomposite for the construction of air-coupled ultrasound transducer

2014 IEEE International Ultrasonics Symposium, 2014
In some cases of ultrasound nondestructive evaluation, the use of a coupling agent can damage the object being inspected, thus requiring the use of an air-coupled ultrasound transducer. This article presents a specific configuration of a graded piezocomposite of central frequency of 820 kHz to be used for constructing a transducer capable of emitting ...
D. J. Costa, F. Buiochi, L. Elvira
openaire   +1 more source

Numerical Modeling of Air-Coupled Ultrasound with EFIT

1995
In this paper the Elastodynamic Finite Integration Technique (EFIT) [1] is applied to an isotropic, inhomogeneous, three media acoustic-elastic problem. We consider three media: an acoustic medium, air, above an elastic layer of acrylic, and another layer of air below the elastic layer.
Rudolph, M., Fellinger, P., Langenberg, K., Chimenti, Dale   +3 more
openaire   +2 more sources

Development of a Methodology for the Characterisation of Air-coupled Ultrasound Probes

AIP Conference Proceedings, 2010
This study is aimed at developing a technique for the characterisation of air‐coupled ultrasound probes, starting from the analysis of the mechanical behaviour of the probe membrane. The vibratory behaviour of the emission membrane is studied using laser‐Doppler vibrometry techniques with high frequency demodulation system (20 MHz).
Paolo Pietroni, Gian Marco Revel, E. P. Tomasini   +2 more
openaire   +1 more source

EVALUATION OF AIR COUPLED ULTRASOUND FOR COMPOSITE AEROSPACE STRUCTURE

AIP Conference Proceedings, 2009
Non‐contact air coupled ultrasound suffers from the high acoustic impedance mismatch characteristics of air to solid interfaces. Advances in transducer technology, particularly MEMS, have improved the acoustic impedance match at the transmission stage and the signal to noise at the reception stage.
H. Tat, G. Georgeson, R. Bossi, Donald O. Thompson, Dale E. Chimenti   +4 more
openaire   +1 more source

Development of air-coupled ultrasound transducers for nondestructive evaluation

2008 IEEE 21st International Conference on Micro Electro Mechanical Systems, 2008
We report the development of air-coupled ultrasound transducers for noncontact nondestructive evaluation applications. Air-coupled ultrasound is an attractive inspection technique for materials or structures that are not suitable for contact or immersion ultrasound inspections. However, due to large acoustic impedance mismatch between air and materials
Xuefeng Wang, Ying Fan, Wei-Cheng Tian, Hyon-Jin Kwon, Stacey Kennerly, Glenn Claydon, Andrew May   +6 more
openaire   +1 more source

Air-coupled ultrasound for testing of batteries and components

The Journal of the Acoustical Society of America
This work describes the use of an air-coupled and through transmission ultrasonic (0.2–1.5 MHz) technique, both at normal and oblique incidence, for the characterization and test of pouch-cell Li-ion (and similar types) batteries and components. Time domain measurements show that it is possible to measure ultrasonic velocity in the battery.
openaire   +2 more sources

Air-coupled ultrasound as a tool for new NDE applications

AIP Conference Proceedings, 2001
Ultrasound testing is a standard non-destructive evaluation method that requires a coupling medium, e.g. water, which cannot be used for some materials. A new commercially available device uses improved transducers and sensitive electronics to enhance the signal-to-noise ratio so that air-coupled ultrasound testing is feasible.
openaire   +1 more source

Air-coupled ultrasound inspection of complex aluminium-CFRP components

2016 IEEE International Ultrasonics Symposium (IUS), 2016
Composite Overwrapped Pressure Vessels (COPVs) are widely used to contain high-pressure fluids. COPVs consist of a thin metallic liner covered with a composite material based on structural fibres. The main function of the liner is to avoid direct contact between composite and chemical agents which can degrade the resin matrix.
Jose Brizuela, Jorge Camacho, Tomas G. Alvarez-Arenas, Jorge Cruza, Ezequiel Poodts   +4 more
openaire   +1 more source

Examination of objects made of wood using air-coupled ultrasound

IEEE Symposium on Ultrasonics, 2002
The authors describe an experimental air-coupled, ultrasonic measurement system that can be used to study the propagation of megahertz signals in wooden plates ranging in thickness from 3 to 25 mm. They also report experimental measurements of the amplitude of transmitted, narrowband, 0.5-MHz signals as a function of the angle of incidence for ...
C.M. Fortunko, M.C. Renken, A. Murray
openaire   +1 more source

Air-coupled Ultrasound for Monitoring the Production of PUR Sandwich Structures

International Polymer Processing, 2010
Abstract Polyurethane sandwich structures are very useful in construction because of their excellent thermal insulating properties. Even though the chemicophysical processes occurring inside the production line crucially affect the quality of the final product, up to now, they are not monitored at all.
F. Siegmund, D. Döring, M. Rheinfurth, E. Haberstroh, G. Busse   +4 more
openaire   +1 more source