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air-coupled ultrasonic testing

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Published: 01 August 2018
Fig. 9 Configurations for air-coupled ultrasonic testing. (a) Through-transmission. (b) Angled beam. (c) Pitch-catch. (d) Guided wave More
Series: ASM Handbook
Volume: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003436
EISBN: 978-1-62708-195-5
...Abstract Abstract This article introduces the principal methodologies and some technologies that are being applied for nondestructive evaluation of composite materials. These include ultrasonic testing (UT), air-coupled UT, laser UT, ultrasonic spectroscopy, leaky lamb wave method, acousto...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006478
EISBN: 978-1-62708-190-0
... in the standard ultrasonic inspection system approach. One method to accomplish this is with air-coupled ultrasonic testing (UT). The technique can be used very effectively on composite materials, such as laminates, honeycombs, and foams. Air-coupled ultrasound inspection has been performed using frequencies from...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.9781627081900
EISBN: 978-1-62708-190-0
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006471
EISBN: 978-1-62708-190-0
... Applications” in this Volume. Improvements in both the performance of piezoelectric materials, matching, and electronics have facilitated opportunities to use air and high-pressure gas-coupled ultrasonics ( Ref 1 , 9 ). Air-coupled ultrasonics has, over a number of years, seen some applications with low...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006461
EISBN: 978-1-62708-190-0
... equipment; poor field adaptability 13 – 15 Air-coupled ultrasonics and immersion ultrasonics … Low-frequency operation allows for inspection of highly attenuative materials. Noncontact scanning capability (air-coupled ultrasonic testing) Transducers are expensive; poor signal-to-noise ratio...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003315
EISBN: 978-1-62708-176-4
... ) introduced a machine capable of 116 Hz. In 1925, Jenkin ( Ref 2 ) tested wires of copper, iron, and steel at 2 kHz, using similar techniques. In 1929, Jenkin and Lehmann ( Ref 3 ) were able to test materials up to 10 kHz using a pulsating air resonance system. Mason ( Ref 4 ) achieved ultrasonic...
Book Chapter

Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003236
EISBN: 978-1-62708-199-3
... the transducer to the test piece. Therefore, it is necessary to use a couplant to eliminate air between the transducer and the test piece for satisfactory contact inspection. Couplants normally used for contact inspection include water, oils, glycerin, petroleum greases, silicone grease, cellulose gum...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006460
EISBN: 978-1-62708-190-0
... with electromagnetic acoustic transducers (EMATs) or air-coupled transducers. As shown in Fig. 1 , a laser-ultrasonic transducer typically has three basic elements: a generation laser, a detection laser, and an interferometer, followed by data acquisition and processing electronic hardware. These elements...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 November 1995
DOI: 10.31399/asm.hb.emde.a0003045
EISBN: 978-1-62708-200-6
... and directionally focusing the waves on the material to be inspected. The ultrasonic transducer is typically coupled to the material by water or oil because of the efficiency in transmitting high-frequency sound waves and because air is unable to support sound waves in the ultrasonic-frequency regime...
Series: ASM Handbook
Volume: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003437
EISBN: 978-1-62708-195-5
... (where R is the ratio of minimum stress to maximum stress) done on a 6090/SiC/25p composite by DWA Aluminum Composites Inc. in an Air Force Title III test program. Samples for this study were not hourglass shape, but had a constant gage section diameter of 5.1 mm (0.20 in.) diameter and were 25 mm (1...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006473
EISBN: 978-1-62708-190-0
.... It provides information on the dimension-measurement applications of ultrasonic inspection methods. ultrasonic imaging inspection area-amplitude blocks distance-amplitude blocks calibration defects WHEN ULTRASONIC NONDESTRUCTIVE TESTING (NDT) was first applied, it was a workmanship standard...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006470
EISBN: 978-1-62708-190-0
... the method in its various implementations suitable for data digitization, immediate interpretation, automation, rapid scanning, in-line production monitoring, and process control. Some of the coupling requirements can be overcome, in some cases, by using gas/air-coupled, laser, and electromagnetic acoustic...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006446
EISBN: 978-1-62708-190-0
... mounted on a wedge aligned at an angle generates Rayleigh waves in the specimen by matching the projected wavelength of the Rayleigh wave in the specimen. Detection of fundamental and second-harmonic Rayleigh waves is accomplished using a noncontact, air-coupled receiver, which picks up the compressional...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006449
EISBN: 978-1-62708-190-0
...., magnetic flux-leakage, Hall-effect sensors, and magnetic-particle techniques), ultrasonic, acoustic emission, guided wave, laser testing, microwave, radiographic, thermal and infrared testing, x-ray diffraction, and visual inspection. Selection of the NDT method depends on product manufacturing...
Book Chapter

Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003235
EISBN: 978-1-62708-199-3
... are as follows: Broadband frequency response of the coupling antennas Efficient coupling through air from the antennas to the material No material contamination problem caused by the coupling Microwaves readily propagate through air, so successive reflections are not obscured by the first one...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006458
EISBN: 978-1-62708-190-0
.... Thus, in contrast to all transducers that do not use inductive coupling to the material under study, including PETs, no mechanical couplant, such as water, oil, or epoxy, is needed between the metal under study and the EMAT. (Exceptions to these statements are air-coupled transducers and laser...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006469
EISBN: 978-1-62708-190-0
... of an interface. Metal/air interfaces produce sharp indications if the interfaces are relatively smooth and essentially parallel to the front surface. If an interface is curved (such as the surface of a large pore) or rough (such as a crack, seam, or lamination) or if it is not ideally reflecting...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006477
EISBN: 978-1-62708-190-0
... = ρ 2 · v 2 . As an example, for a longitudinal wave traveling in an aluminum alloy that interacts with a void filled with air, the reflection coefficient R isalmost 1, because air has an acoustic impedance of 0.0004 g/cm 2 -s (8 × 10 −4 lb/ft 2 -s), while aluminum has approximately 17 × 10 5 g...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005616
EISBN: 978-1-62708-174-0
... separated by two different media and (Eq 2) T = 1 − R where Z 1 = ρ 1 · v 1 and Z 2 = ρ 2 · v 2 . As an example, for a longitudinal wave traveling in an aluminum alloy that interacts with a void filled with air, the reflection coefficient R is almost 1, because air has...