Review of nonlinear ultrasonic guided wave nondestructive evaluation: theory, numerics, and experiments

Abstract

Abstract. Interest in using the higher harmonic generation of ultrasonic guided wave modes for nondestructive evaluation continues to grow tremendously as the understanding of nonlinear guided wave propagation has enabled further analysis. The combination of the attractive properties of guided waves with the attractive properties of higher harmonic generation provides a very unique potential for characterization of incipient damage, particularly in plate and shell structures. Guided waves can propagate relatively long distances, provide access to hidden structural components, have various displacement polarizations, and provide many opportunities for mode conversions due to their multimode character. Moreover, higher harmonic generation is sensitive to changing aspects of the microstructures such as to the dislocation density, precipitates, inclusions, and voids. We review the recent advances in the theory of nonlinear guided waves, as well as the numerical simulations and experiments that demonstrate their utility. 1 Introduction Nonlinear ultrasonic nondestructive evaluation uses interrogation signals at frequencies other than the excitation frequency to detect changes in structural integrity and characterize degradation of materials. Nonlinear ultrasonic methodologies provide improved sensitivity to damage and the ability to identify incipient damage relative to linear methods. In general, linear ultrasonic methods provide good sensitivity to macroscale damage such as long fatigue cracks. However, in many cases, once damage appears at the macroscale, the remaining life is short, severely limiting maintenance decisions. Thus, characterization of incipient damage could facilitate a paradigm shift in operations of structural systems from schedule-based to condition-based maintenance that would ultimately enhance safety and reduce life cycle costs. Nonlinear ultrasonics is a broad discipline 1,2 which encompasses many specialized techniques reliant upon nonlinear material behavior to detect and/or characterize incipient damage. Some of these include nonlinear resonant ultrasound spectroscopy, 3 nonlinear elastic wave spectroscopy, 4-6 and second-harmonic generation.

Nonlinear Lamb wave mixing for assessing localized deformation during creep

“…It uses the interrogation signals at frequencies other than the excitation frequency to detect changes in structural integrity and characterization of material degradation [1]. It relies on the nonlinear stress-strain behavior or nonlinear Hooke's law that is dominated by higher order elastic constants in isotropic elastic solid.…”

Numerical studies of nonlinear ultrasonic guided waves in uniform waveguides with arbitrary cross sections

“…Such challenge may be overcome by using nonlinear ultrasonic methods, as they are much more sensitive to incipient damages. [2][3][4][5] In recent years, nonlinear ultrasonic guided waves, combining advantages of nonlinear ultrasound and guided waves, have emerged as a useful tool for the characterization of incipient damages in large structures, as guided waves can travel a long distance with little loss in energy and therefore provide capability for the remote inspection of areas with difficult access. 5 The theory of nonlinear guided waves was first demonstrated in 1990s by Deng.…”

“…[2][3][4][5] In recent years, nonlinear ultrasonic guided waves, combining advantages of nonlinear ultrasound and guided waves, have emerged as a useful tool for the characterization of incipient damages in large structures, as guided waves can travel a long distance with little loss in energy and therefore provide capability for the remote inspection of areas with difficult access. 5 The theory of nonlinear guided waves was first demonstrated in 1990s by Deng. 6,7 Two conditions for the generation of the cumulative second harmonic wave were summarized using perturbation method and modal analysis: (1) phase velocity matching; (2) non-zero power transfer from the primary to the second harmonic wave.…”

Annual highlights

“…This topic is a bit peripheral to the Optical Engineering journal scope, but I included it because it was tightly coupled with an SPIE conference in this technical area. Interestingly, the review paper on ultrasonic nondestructive evaluation was also our top-cited paper in 2016, 5 so I feel good about this decision. Our top 2016 downloaded paper on laser space debris removal was actually published in advance online as part of our Special Section on Laser Damage III, which appears in the January 2017 volume.…”

“…The top ten downloaded papers addressed laser space debris removal, 1 hyperspectral camera design, 2 satellite optical downlinks, 3 freeform optics, 4 ultrasonic nondestructive evaluation, 5,6 microwave photonics, 7 optical-wireless networking, 8 and telescope mirror metrology. 9 The tenth on the list was actually my July editorial on performing excellent peer reviews.…”