Nonlinear Elastic Wave NDE II. Nonlinear Wave Modulation Spectroscopy and Nonlinear Time Reversed Acoustics
04 May 2005-Vol. 760, Iss: 1, pp 385-392
TL;DR: In this article, the authors present two different methods of nonlinear NDE that provide not only damage detection but location as well, and apply the focusing properties of TRA and the nonlinear properties of cracks to locate them.
Abstract: This paper presents the second part of the review of Nonlinear Elastic Wave Spectroscopy (NEWS) in NDE, and describe two different methods of nonlinear NDE that provide not only damage detection but location as well. Nonlinear Wave Modulation Spectroscopy is based on the application of an ultrasonic probe signal modulated by a low frequency vibration. Damage location can be obtained by application of Impulse Modulation Techniques that exploit the modulation of a short pulse reflected from a damage feature (e.g. crack) by low frequency vibration. Nonlinear Time Reversed Acoustic methods provide the means to focus acoustic energy to any point in a solid. In combination, we are applying the focusing properties of TRA and the nonlinear properties of cracks to locate them.
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TL;DR: In this paper, the authors reviewed the overall progress in nonlinear ultrasonic technique with the brief introduction of basic principle in the application of each nonlinear Ultrasonic phenomenon, including higher harmonic generation, subharmonic generation, nonlinear resonance, or mixed frequency response.
Abstract: The nondestructive assessment of the damage that occurs in components during service plays a key role for condition monitoring and residual life estimation of in-service components/structures. Ultrasound has been widely utilized for this; however most of these conventional methods using ultrasonic characteristics in the linear elastic region are only sensitive to gross defects but much less sensitive to micro-damage. Recently, the nonlinear ultrasonic technique, which uses nonlinear ultrasonic behavior such as higher-harmonic generation, subharmonic generation, nonlinear resonance, or mixed frequency response, has been studied as a positive method for overcoming this limitation. In this paper, overall progress in this technique is reviewed with the brief introduction of basic principle in the application of each nonlinear ultrasonic phenomenon.
581 citations
TL;DR: In this paper, a review of modeling approaches used for nonlinear crack-wave interactions is presented, including models of crack-induced elastic, thermo-elastic and dissipative nonlinearities.
248 citations
TL;DR: A modified VAM (MVAM) is developed that can circumvent existing problems with practical implementation and provide higher sensitivity in bolt early looseness monitoring, and is compared with the proposed MMSE-based DI with nonlinear DI of traditional VAM method.
125 citations
TL;DR: In this article, the authors used nonlinear elastic wave spectroscopy (NEWS) to discriminate between linear and nonlinear scatterers, and thus to ultimately image and characterize damaged regions.
Abstract: Nonlinear elastic wave spectroscopy (NEWS) has been shown to exhibit a high degree of sensitivity to both distributed and isolated nonlinear scatterers in solids. In the case of an isolated nonlinear scatterer such as a crack, by combining the elastic energy localization of the time reversal mirror with NEWS, it is shown here that one can isolate surfacial nonlinear scatterers in solids. The experiments presented here are conducted in a doped glass block applying two different fixed frequency time-reversed signals at each focal point and scanning over a localized nonlinear scatterer (a complex crack). The results show a distinct increase in nonlinear response, via intermodulation distortion, over the damaged area. The techniques described herein provide the means to discriminate between linear and nonlinear scatterers, and thus to ultimately image and characterize damaged regions.
78 citations
TL;DR: An overview of research developments related to the nonlinear vibroacoustic modulation technique used for structural damage detection, with a major focus on monitoring approaches, modeling aspects, actuation/sensing, signal processing, and application examples.
Abstract: We present an overview of research developments related to the nonlinear vibroacoustic modulation technique used for structural damage detection. The method of interest is based on nonlinear interactions of a low-frequency pumping wave and a high-frequency probing wave. These two waves are introduced to monitored structures simultaneously. Then the presence of damage is exhibited by additional frequency components that result from nonlinear damage-wave interactions. A vast amount of research has been performed in this area over the last two decades. We aim to present the state-of-the-art of these developments. The major focus is on monitoring approaches, modeling aspects, actuation/sensing, signal processing, and application examples.
68 citations
Cites methods from "Nonlinear Elastic Wave NDE II. Nonl..."
...VAM has been also used in connection with time reversal processing in order to locate sources of nonlinearity.(72,73) Most recently, VAM data has been analyzed using the cointegration technique adopted from the field of econometrics....
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01 Jan 1998
TL;DR: The San Onofre Detector as mentioned in this paper was designed and constructed at the University of Southern California (USC) with a projected sensitivity to m 2 of 10?3 eV 2 and to sin 2 2 2 of 0.1.
Abstract: i Preamble While the design of the San Onofre Detector is complete and its construction in progress, long and unexpected delays have so far prevented construction of the underground vault. These delays have been caused in part by legal issues related to the sublease, ownership, and later decomission of the lab site, which is on Federal land leased by the Southern California Edison Company, and, most recently, by environmental rules such as the Federal Acts related to the gnatcatcher bird, which was declared an Endangered Species about a year ago at a time we were about to begin construction. An order from the Fish and Wildlife Services through the ooces of the Marine Corps (Camp Pendleton) and the Edison Company prohibits construction during most of the year. The reason given is that construction machinery produces a noise level at 450 feet (the site of the only close gnatcatcher pair) of 70 db which is, in the Service's view, \signiicantly higher" than the ambient noise, documented as 68 db, from Marine Corps jets, tank excercises, and Interstate 5. With construction held up until mid summer or longer, and fearful of further rules and hassles, we felt compelled to explore alternate sites, of which Palo Verde, near Phoenix, AZ, looks optimal. The three-reactor site, owned by Arizona Public Service Company, is eager to accomodate us, provide services, and build the lab \at cost." Clearly, this change of reactor site does not aaect the physics, the detector, the technical parameters, or the cost. The sensitivity of the experiment, considering the background cycles, will not be aaected either. Agreements between Caltech and APSC covering construction and lease have been signed, and excavation is in progress as of this writing. The cost of the underground lab will be shared by Caltech and Stanford University, with Caltech acting as legal partner and supervisor. Below we present a comprehensive review of the work done. The text is based on the Ph.D. thesis by Brian Cook. ii Abstract A detector for the study of neutrino oscillations with a projected sensitivity to m 2 of 10 ?3 eV 2 and to sin 2 2 of 0.1 is described. It is to be installed 800 m from three pressurized water reactors at the Palo Verde Nuclear Generating Station near Phoenix, Arizona. The detector is segmented and lled with 12 tons of gadolinium-loaded liquid scintillator. It will be placed in an …
159 citations
01 Mar 1998
1 citations