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.
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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.
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02 Apr 2015
TL;DR: In this paper, the authors investigate the physics of bend-guided wave in bends, arguing the strong role of geometry and curvature effects in causing mode confinement, and reveal the possibility of bendguided modes of the shear-horizontal (SH) family, in addition those of the Rayleigh-Lamb family reported earlier in the literature.
Abstract: Ultrasonic guided waves are attractive for rapid remote screening of large structures and today they are widely used in several practical applications including the inspection of pipe and plate installations. More recently, guided wave modal solutions confined in extended local features have attracted much research interest, offering the possibility of inspecting complex geometric or topographical features. Such feature-guided wave (FGW) modes have been reported in plate waveguides with local cross-section variation or curvature, and in annular circular cylinders with cross-sectional anomalies. This paper focuses on FGW phenomena in 90 degree structural bends in plate structures, which commonly occur in various industrial structures. Modal studies are carried out using the Semi-Analytical Finite Element (SAFE) method, while 3D finite element (FE) simulations are used to gain visualization of results and also obtain cross-validation. Our studies reveal, perhaps for the first time, the possibility of bend-guided modes of the shear-horizontal (SH) family, in addition those of the Rayleigh-Lamb family reported earlier in the literature. This mode has attractive properties including low attenuation and limited dispersion. We investigate effects of plate thickness and bend radius on the physics of FGW in bends, arguing the strong role of geometry and curvature effects in causing mode confinement. Preliminary experiments have also been carried out to validate the existence of such bend-guided mode.
6 citations