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air-coupled ultrasound transducers

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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
.... The article concludes with information on immersion or contact type focused search units. air-coupled ultrasound transducers couplants electromagnetic acoustic transducers laser ultrasound phased array transducers magnetostriction transducers piezoelectric transducer transduction modalities...
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
... application ( Ref 14 ). The use of high-power tone-burst operation and the reflection of most of the energy at the first interface back to the transducer suggest that air-coupled UT implementation should use the TT ultrasound or pitch-catch operational modes. Figure 9 shows the configurations commonly...
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
... sensitivity for air-coupled piezoelectric transducer application ( Ref 14 ). The use of high-power tone-burst operation and the reflection of most of the energy at the first interface back to the transducer suggest that air-coupled UT implementation should use the TT ultrasound or pitch-catch operational...
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.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.a0006466
EISBN: 978-1-62708-190-0
... transducer located beneath the sample, as illustrated in Fig. 1 . Because this ultrasound cannot travel through air (making it an excellent tool for crack, void, and disbond detection), a fluid couplant is used to bring the ultrasound to the sample. Distilled water, spectrophotometric-grade alcohol...
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.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 Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006461
EISBN: 978-1-62708-190-0
...Abstract Abstract This article provides an overview of the characteristics of Rayleigh waves plus methods for generation and detection of waves, including using piezoelectric transducers or noncontact techniques such as lasers, electromagnetic acoustic transducers, or air-coupled ultrasonics...
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.a0006473
EISBN: 978-1-62708-190-0
... holes of the same diameter. The difference is a function of both transducer frequency and distance from search unit to the hole end. A typical design for a test block that contains an FBH, used with longitudinal waves, is shown in Fig. 1(a) . In using such a block, ultrasound is directed from...
Series: ASM Handbook
Volume: 5
Publisher: ASM International
Published: 01 January 1994
DOI: 10.31399/asm.hb.v05.a0001226
EISBN: 978-1-62708-170-2
..., shop, and other soils Chlorinated-solvent degreaser (inhibited trichloroethylene, for example) Aluminum and zinc Castings, open-mesh air filters, used automotive carburetor parts, valves, switch components, drawn wire Chips, lubricants, and general grime Moderately alkaline, specially inhibited...
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...
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: 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.a0006452
EISBN: 978-1-62708-190-0
... without the safety and access issues associated with radiography. A basic ultrasonic measurement involves injecting a pulse of ultrasound into a component using a suitable transducer and then using the same transducer to record the returning echoes as a function of time, termed an A-scan. If the speed...
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
... from the air-coupled transducer and are proportional to (but not equal to) the absolute out-of-plane displacement amplitudes, so the ratio A 2 / A 1 2 is proportional to the acoustic nonlinearity parameter (β). Fig. 9 (a) Example of typical time domain signal. (b) Corresponding frequency...
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
... ultrasonic, electromagnetic, and eddy-current NDE full-body scans in a single pass ( Ref 2 , 5 ), which saves on time and equipment space requirements. Combination systems typically include multiple orientations of transducers, receivers, probes, and sensors so they can detect defects in multiple...
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: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006438
EISBN: 978-1-62708-190-0
... transducers, water or air immersion transducers, or laser velocimetry sensors. Guided wave ultrasound using piezoelectric, EMAT, or magnetostrictive sensors. This is a growing inspection approach because of advancement of techniques for focusing, steering, temperature, and dispersion curve compensation...