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guided wave modes

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Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006441
EISBN: 978-1-62708-190-0
... of the other contexts in which its use is growing in other evolving applications. It discusses the various guided wave modes and their selection criteria. The article provides information on considerations for mode control and the sensitivity of the GWT to the defect. It also shows some examples of advanced...
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
... at which a particular volume must be interrogated may dictate using guided waves. As described subsequently, both PETs and EMATs could generate the wave modes inferred by these statements. However, the practical range of angles available when using some EMATs is different from those available with PETs...
Series: ASM Handbook
Volume: 13A
Publisher: ASM International
Published: 01 January 2003
DOI: 10.31399/asm.hb.v13a.a0003658
EISBN: 978-1-62708-182-5
... of the structure with small changes in frequency, and these signals constructively combine to form wave packets that travel within structure much like a wave guide. Some wave packets, or modes, can travel long distances without significant attenuation once they are formed ( Ref 11 ), and these are the richest...
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
... with horns for high power and for a range of specialized nondestructive testing (NDT) applications. Magnetostriction is used for lower frequencies; a common application now is guided wave generation ( Ref 6 ). In looking more widely at options for ultrasound generation that generally are considered...
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
... wave will mode convert to a guided wave within the wedge-shaped section of an inclined crack, and the amplitude detected depends on whether one is measuring the in-plane or out-of-plane component of the wave, as well as the frequency-thickness product at that point ( Ref 2 , 51 ). Fig. 11...
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
... generation and detection are discussed in the article “Guided Wave Testing” in this Volume. Fig. 8 Example of dispersion curves, calculated for aluminum 1.0 mm thick, with symmetric and antisymmetric modes, shown in normalized units (MHz-mm). A 0 and S 0 are fundamental modes; index indicates...
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
... that is considerably less than the theoretical maximum. Attenuation in a test piece can limit the path length. The practical limit for inspection depth varies with the type and condition of the test material, wave mode, test frequency, and system sensitivity. Furthermore, it is highly desirable for all ultrasonic...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005590
EISBN: 978-1-62708-174-0
..., the electrode positive mode is favored; when maximum heat is desired, the electrode negative mode is favored. In general, square-wave power sources are much less susceptible to arc rectification than sine-wave power sources, although it still sometimes occurs. Equipment Power Supplies Power supplies...
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...
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002452
EISBN: 978-1-62708-194-8
...) enclose the bubbles for a class. Fig. 2 Young's modulus, E , plotted against density, ρ, for various engineered materials. The heavy envelopes enclose data for a given class of material. The diagonal contours show the longitudinal wave velocity. The guide lines of constant E /ρ, E 1/2 /ρ...
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006472
EISBN: 978-1-62708-190-0
... technique provides information not only on the diffracted waves but also on the different propagation modes, such as: The lateral wave: This wave mode propagates following the shortest path between the transducers, and it is the first signal in the B-scan screen. This signal represents the surface...
Book Chapter

Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006474
EISBN: 978-1-62708-190-0
... frequencies from 3 to 5 MHz in a tone-burst mode, creating wave trains of 100 µs duration. Parts could then be scanned to give larger-area inspection. Fig. 1 Schematic showing elements in the real-time ultrasonic imaging system. Courtesy of Pacific Northwest National Laboratory The technique has...
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
... of practical application. There are a variety of wave modes available for nonlinear ultrasonics (NLU), including bulk, surface, and guided waves. An advantage of NLU is that the acoustic nonlinearity parameter (β) measured using any wave type can be related back to the material nonlinearity, meaning...
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
... and inspection requirements. A further constraint is then the limited viewing angles for an inspection and the inspection methodology (e.g., pulse-echo) and inspection system employed, which defines wave type, frequency, and wave-field characteristics, including the need for required coverage and resulting data...
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: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003436
EISBN: 978-1-62708-195-5
... macrocracks, and voids in composites structures. The ultrasonic method itself uses longitudinal, shear, Lamb, Rayleigh, or guided waves for various measurements on composite materials. Wave parameters, including acoustic attenuation and speed, can be used to determine materials properties and characteristics...
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
..., matrix macrocracks, and voids in composite structures. The ultrasonic method itself uses longitudinal, shear, Lamb, Rayleigh, or guided waves for various measurements on composite materials. Wave parameters, including acoustic attenuation and speed, can be used to determine materials properties...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006400
EISBN: 978-1-62708-192-4
... and detection of leaks, rolling damage, and cracks. Acoustic emission testing is a CM technique that has been used to analyze emitted sound waves caused by defects or discontinuities. It is the phenomenon of transient waves generated due to the rapid release of strain energy caused by small deformations...
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
... images of a sample throughout its entire thickness (reflection mode sometimes is employed). In operation, ultrasound is introduced to the bottom surface of the sample by a piezoelectric transducer, and the transmitted wave is detected on the top side by a rapidly scanning laser beam. The other two...
Series: ASM Handbook
Volume: 13A
Publisher: ASM International
Published: 01 January 2003
DOI: 10.31399/asm.hb.v13a.a0003653
EISBN: 978-1-62708-182-5
... used method because of the complex nature of the waves and noise signals generated during its application. The new developments in signal processing and the hardware and software designs of ultrasonic guided wave methods have made it possible to sense defects in inaccessible areas under coatings...