Novel method of defect identification in bent structures through feature-guided wave detection using fiber Bragg grating sensors
28 Sep 2015-Vol. 9634, pp 49-52
TL;DR: In this article, feature-guided waves (FGW) have emerged as a promising technique for structural health monitoring as they are well confined in local features such as bends and welds, and a novel method for identifying defects in 90 transverse bent structures through FGW detection using fiber Bragg gratings.
Abstract: Feature-guided waves (FGW) have emerged as a promising technique for structural health monitoring as they are well confined in local features such as bends and welds. In this paper, we propose and demonstrate a novel method for identifying defects in 90 transverse bent structures through FGW detection using fiber Bragg gratings. Our experimental results are in excellent agreement with results predicted using 3D-Finite Element (FE) simulations of the bent structure.
Citations
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TL;DR: In this article, a fiber Bragg grating based technique was proposed to detect anomalies or defects in plate structures with transverse bends, both in the case of defect-free and transverse defects.
Abstract: Harnessing of ultrasonic guided waves confined in local features such as bends and welds, known as feature-guided waves, has emerged as a promising technique for non-destructive testing and structural health monitoring of industrial and aerospace structures. This article introduces a fiber Bragg grating based technique which uses feature-guided waves to detect anomalies or defects in plate structures with transverse bends. We are able to obtain good consistency between simulation and experimental results, both in the case of defect-free bent plates and those with transverse defects. Such results establish fiber Bragg gratings as a viable alternative to conventional techniques for structural health monitoring of bent plates.
20 citations
Cites background from "Novel method of defect identificati..."
...The TOF between the two wave packets would help to precisely locate the defect with respect to the FBG position (Ray et al., 2015)....
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TL;DR: Fiber Bragg gratings are shown to be effective in detecting changes to L(0,2) modal characteristics, providing a novel route to health monitoring of pipe assets.
14 citations
TL;DR: This work conducted several setups to determine the optimal ones to launch and detect ultrasonic Lamb waves, especially in non-homogeneous specimens, and verified the existence of Lamb modes and good correspondence was achieved.
Abstract: Lamb waves have emerged as a valuable tool to examine long plate-like structures in a faster way compared to conventional bulk wave techniques, which make them attractive in non-destructive testing. However, they present a multimodal and dispersive nature, which hinders signal identification. Oblique incidence is one of the most known methods to generate and receive Lamb waves and it is applied in different experimental arrangements with different types of sensors. In this work, several setups were conducted and compared to determine the optimal ones to launch and detect ultrasonic Lamb waves, especially in non-homogeneous specimens. The chosen arrangements were contact with angle beam transducers, immersion in a water tank, localised water coupling using conical containers and air coupling. Plates of two different materials were used, stainless steel and Portland cement mortar. Theoretical and experimental dispersion curves were compared to verify the existence of Lamb modes and good correspondence was achieved.
4 citations
Cites background or methods from "Novel method of defect identificati..."
...In this work, different sinusoidal tone burst signals (which produce narrowband excitation) varying in frequency [39,44,47,70,76] were launched in the tested plate and then every received spectrogram was combined into one [37] (hereafter, the combined spectrogram)....
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...Five [11,36,39,76] and ten cycles [14,58,78] are a reasonable number of cycles for burst signals....
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TL;DR: In this article, an impact monitoring system based on fiber bragg grating (FBG) sensor is constructed, where the frequency domain information of the signal can be obtained by Fourier transform.
Abstract: As a kind of structure commonly used in satellite, carbon fiber composite honeycomb sandwich panels are vulnerable to various kinds of damage, especially low-velocity impact damage in the process of using. In this paper, an impact monitoring system based on Fiber Bragg Grating (FBG) sensor is constructed. The frequency domain information of the signal can be obtained by Fourier transform. Monitoring results of different impact points show that the natural frequency of structure is 110Hz and 380Hz, which amplitude of different natural frequency is changed with position of impact point. The energy status of impact response signal can be obtained by wavelet packet analysis. The monitoring results of the same impact point shows that the change of the sensor signal is obvious in thirteenth order and energy size is related to the distance and angle between the impact point and sensor.
References
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Book•
01 Jan 1969
TL;DR: In this article, the authors describe the physical fundamentals of ultrasonics and materials up to the most sophisticated methods for nondestructive testing of solid material using ultrasonic waves for defects such as cavities, nonbonding, and strength variations.
Abstract: Nondestructive testing of solid material using ultrasonic waves, for defects such as cavities, nonbonding, and strength variations, is treated in this book from the physical fundamentals of ultrasonics and materials up to the most sophisticated methods. The book is written at a level which should make it accessible to readers with some knowledge of technical mathematics. Physical laws are explained in elementary terms, and more sophisticated treatments are also indicated. After the fundamentals, instrumentation and its application is extensively reported. Tricks and observations from thirty years of experience in the field are included. The third part of the book presents test problems related to special materials or ranges of modern heavy industry, including recent applications such as those in nuclear power plants. This fourth edition features improved presentation of certain fundamental physical facts, updated reports on electronic instrumentation, and new applications in the nuclear and space industries.
1,751 citations
01 Jan 2009
592 citations
"Novel method of defect identificati..." refers methods in this paper
...Active sensing techniques involving guided Lamb wave modes in the frequency range of 10 kHz to 1 MHz are a powerful way of identification and localization of defects in the SHM of plate-like structural elements [2]....
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TL;DR: Instrumentation for long range, guided wave inspection of pipework is now commercially available and as discussed by the authors discusses the principles of the method and reviews the results of site experience, which was originally designed to work on pipes that were either un-coated or covered with, for example, epoxy paint.
Abstract: Instrumentation for long range, guided wave inspection of pipework is now commercially available. This paper discusses the principles of the method and reviews the results of site experience. The technique was originally designed to work on pipes that were either un-coated or covered with, for example, epoxy paint. Recent tests have shown promising results with more attenuative coatings and these are discussed.
165 citations
"Novel method of defect identificati..." refers methods in this paper
...The element size was selected in order to have at least 12 elements per SHB mode wavelength, in order to avoid numerical instability [9]....
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...Based on the stability criterion, an iteration step time of 1e-8 seconds was used for the simulation [9]....
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TL;DR: In this article, the authors address methods to dramatically enhance computational efficiency by only meshing a local region of the material surrounding the defect; this reduction requires some kind of boundary, or boundary condition, which absorbs, rather than reflects, any waves arriving at the exterior of the modeled domain.
Abstract: Finite Element models for simulating wave propagation and scattering from defects are vital for ultrasonic methods in NDE. This article addresses methods to dramatically enhance computational efficiency by only meshing a local region of the material surrounding the defect; this reduction requires some kind of boundary, or boundary condition, which absorbs, rather than reflects, any waves arriving at the exterior of the modelled domain. A variety of approaches exist and we take two approaches, Perfectly Matched Layers (PML) and Absorbing Regions, selected specifically as they are readily implemented in commercially available Finite Element packages without requiring the source code. We illustrate both bulk and guided waves, and analysis is used to guide the performance, and thus to plan the use, of each of them. Finally, application examples illustrate the gains yielded by absorbing layer methods in terms of reducing both model size and unwanted reflections.
163 citations
"Novel method of defect identificati..." refers background in this paper
...Likewise, in order to avoid reflections from the edges and to achieve clear simulation results, an absorbing region [10] was attached to each side of the bent plate....
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TL;DR: A novel, sensitive, simple, and robust strain interrogation technique is analyzed and experimentally tested, which achieves high dynamic strain sensitivity of 45 picostrain/ radicalHz rms at 3 kHz.
Abstract: A novel, sensitive, simple, and robust strain interrogation technique is analyzed and experimentally tested. By locking a laser wavelength to the midreflection wavelength of a standard fiber Bragg grating and measuring the error signal, we achieve high dynamic strain sensitivity of 45 picostrain/Hz rms at 3 kHz, where the dominant noise in the experiment is the laser frequency noise.
132 citations
"Novel method of defect identificati..." refers methods in this paper
...The reflected signal consisting of an amplitude modulation corresponding to the dynamic strain [11] is extracted using a circulator and fed into a PIN-TIA optical receiver....
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