Microwave and millimetre-wave non-destructive testing and evaluation (NDT&E) has a long history dating back to the late 1950s (Bahr 1982
Microwave non-destructive testing methods
; Zoughi 2000
...Microwave Non-destructive testing and evaluation principles
; Feinstein 1967
Surface crack detection by microwave methods
; Ash 1973 In
3rd European Microwave Conference
; Auld 1981
Phys. Technol.
12
, 149–154; Case 2017
Mater. Eval.
75
). However, sustained activities in this field date back to the early 1980s (Zoughi 1995
Res. Nondestr. Eval.
7
, 71–74; Zoughi 2018
Mater. Eval.
76
, 1051–1057; Kharkovsky 2007
IEEE Instrumentation & Measurement Magazine
10
, 26–38). Owing to various limitations associated with using microwaves and millimetre waves for NDT&E, these techniques did not see much utility in the early days. However, with the advent and prevalence of composite materials and structures, in a wide range of applications, and technological advances in high-frequency component design and availability, these techniques are no longer considered as ‘emerging techniques’ (Zoughi 2018
Mater. Eval.
76
, 1051–1057; Schull 2002
Nondestructive evaluation: theory, techniques, and applications
). Currently, microwave and millimetre-wave NDT&E is a rapidly growing field and has been more widely acknowledged and accepted by practitioners over the last 25+ years (Case 2017
Mater. Eval.
75
; Bakhtiari 1994
IEEE Trans. Microwave Theory Tech
.
42
, 389–395; Bakhtiari 1993
Mater. Eval.
51
, 740–743; Bakhtiari 1993
IEEE Trans. Instrum. Meas.
42
, 19–24; Ganchev 1995
IEEE Trans. Instrum. Meas.
44
, 326–328; Bois 1999
IEEE Trans. Instrum. Meas.
48
, 1131–1140; Ghasr 2009
IEEE Trans. Instrum. Meas.
58
, 1505–1513). Microwave non-destructive testing was recently recognized and designated by the American Society for Nondestructive Testing (ASNT) as a ‘Method’ on its own (Case 2017
Mater. Eval.
75
). These techniques are well suited for materials characterization; layered composite inspection for thickness, disbond, delamination and corrosion under coatings; surface-breaking crack detection and evaluation; and cure-state monitoring in concrete and resin-rich composites, to name a few. This work reviews recent advances in four major areas of microwave and millimetre-wave NDT&E, namely materials characterization, surface crack detection, imaging and sensors. The techniques, principles and some of the applications in each of these areas are discussed.
This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.
•A long duration low amplitude signal segment distinguishes intermoult lobsters.•A 7 MHz centre frequency transducer generates the distinguishing signal segment.•Pre-moult structural changes beneath ...the exoskeleton explain changed response.•A foundation is indicated for an NDT based ultrasonic crustacean pre-moult detector.•Valuable insights of acoustic interactions with the lobster exoskeleton are presented.
This study examined the novel application of non-destructive testing (NDT) ultrasound for detecting approaching moult in juvenile tropical rock lobsters (TRL), Panulirus ornatus. TRL juveniles are highly cannibalistic in culture, with up to 25% of lobsters lost to cannibalism at each moult. A pre-moult sensor could prove pivotal as moulting lobsters are the primary victim of cannibalistic predation and a reliable indication of pre-moult could trigger a suitable intervention measure. A series of structural changes take place beneath the exoskeleton in preparation for moulting, which leave little indication of pre-moult on the lobster’s external surface. An opportunity exists for penetrative pre-moult detection via ultrasonic acoustic stimulation through the exoskeleton. NDT ultrasound is proposed as a possible pre-moult sensing technology. NDT ultrasound is comparatively low-cost, a requirement for replicated deployment to industry. This study explores the acoustic response from five NDT ultrasound transducers by scanning the dorsal carapace of juvenile TRLs.
A small diameter (13 mm) transducer with a 7 MHz centre frequency produced and measured a low amplitude, long duration signal segment in intermoult lobsters that was not present in pre-moult lobsters, forming a basis to distinguish intermoult from pre-moult lobsters. It is proposed that muscle detachment and growth of the new integument and a separating membrane disrupt sound conduction beneath the exoskeleton in a similar fashion to delaminated joint detection methods used in industry. These results show promise that a pre-moult sensor may be able to be based on NDT ultrasonic technologies and provide guidance for refining transducer specifications for further research.
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Abstract
The concreted conditions assessment of the systems is an essential aspect of security assessment programs. In situ measurements of Ultrasonic Pulse Velocity (UPV) may be indicative of the ...level of damage in the original concrete. UPV influenced by the specific characteristics of the mixture. In situ UPV measurements can be indicative of the level of damage in the original concrete. The research purpose is the damage classification, UPV test interpretation (strength, density, elasticity modulus, Concrete Quality Designation (CQD)), and determines the level of structural damage visually so that more accurate inspection results. The research result showed that the plastic hinge was more damaged than other parts of the beam-column joints. The UPV test obtained density 0.84-1.03 g/cm
3
, CQD 10% -20%, static elastic modulus 7.68-8.39 Gpa according to 3,4 including very poor and visually is included in category IV spalling off of covering concrete (crack width > 2mm). The use of UPV as supporting assessment for classification, repair, and maintenance of structures. If density, CQD, and elastic modulus of defining very poor classification, the structure that needs immediate repair. The use of UPV is faster, without damaging parts of the structure, and also induces damage to the core specimens as a result of the coring process, making it faster and more economical.
Pipelines play an important role in the national/international transportation of natural gas, petroleum products, and other energy resources. Pipelines are set up in different environments and ...consequently suffer various damage challenges, such as environmental electrochemical reaction, welding defects, and external force damage, etc. Defects like metal loss, pitting, and cracks destroy the pipeline’s integrity and cause serious safety issues. This should be prevented before it occurs to ensure the safe operation of the pipeline. In recent years, different non-destructive testing (NDT) methods have been developed for in-line pipeline inspection. These are magnetic flux leakage (MFL) testing, ultrasonic testing (UT), electromagnetic acoustic technology (EMAT), eddy current testing (EC). Single modality or different kinds of integrated NDT system named Pipeline Inspection Gauge (PIG) or un-piggable robotic inspection systems have been developed. Moreover, data management in conjunction with historic data for condition-based pipeline maintenance becomes important as well. In this study, various inspection methods in association with non-destructive testing are investigated. The state of the art of PIGs, un-piggable robots, as well as instrumental applications, are systematically compared. Furthermore, data models and management are utilized for defect quantification, classification, failure prediction and maintenance. Finally, the challenges, problems, and development trends of pipeline inspection as well as data management are derived and discussed.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Early detection of fatigue cracks and accurate measurements of the crack growth play an important role in the maintenance and repair strategies of steel structures exposed to cyclic loads during ...their service life. Observation of welded connections is especially of high relevance due to their higher susceptibility to fatigue damage. The aim of this contribution was to monitor fatigue crack growth in thick welded specimens during fatigue tests as holistically as possible, by implementing multiple NDT methods simultaneously in order to record the crack initiation and propagation until the final fracture. In addition to well-known methods such as strain gauges, thermography, and ultrasound, the crack luminescence method developed at the Bundesanstalt für Materialforschung und -prüfung (BAM), which makes cracks on the surface particularly visible, was also used. For data acquisition, a first data fusion concept was developed and applied in order to synchronize the data of the different methods and to evaluate them to a large extent automatically. The resulting database can ultimately also be used to access, view, and analyze the experimental data for various NDT methods. During the conducted fatigue tests, the simultaneous measurements of the same cracking process enabled a comprehensive comparison of the methods, highlighting their individual strengths and limitations. More importantly, they showed how a synergetic combination of different NDT methods can be beneficial for implementation in large-scale fatigue testing but also in monitoring and inspection programs of in-service structures - such as the support structures of offshore wind turbines.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pulsed eddy current (PEC) is based on the electromagnetic induction principle, which is widely used in the metal industry for nondestructive testing (NDT) due to its unique advantages, such as fast ...response, great penetration depth, and lift-off tolerance. Eddy current diffuses in a complex manner with the diffusion velocity uneven in space and time. A full picture of the diffusion velocity field enhances physical insight into PEC detection. This article proposes a novel point-tracing method for velocity field calculation. The eddy current diffusion process is divided into three stages and their velocity fields are calculated, respectively. The complete field is then visualized. The calculated results correspond to the phenomenon observed in numerical simulations. Furthermore, the relationship has been analyzed between the properties of the planar conductor, probe lift-off, and the diffusion velocity field, according to the proposed method.
Inspection of thin and multi-depth delamination and foreign inclusion defects inside glass fiber reinforced polymer (GFRP) composites is a challenge for traditional non-destructive testing (NDT) ...techniques. Terahertz (THz) and X-ray computed tomography (CT) are two prevalent NDT methods, which also have their unique advantages and relative weakness individually. Specifically, in our previous study, it is found that THz NDT method has a higher contrast and X-ray CT NDT method has a higher resolution for detecting defects in GFRP composites. In this paper, a new fusion algorithm applied to the THz and X-ray CT NDT imaging data, based on the combination of saliency region analysis (SRA) and wavelet based multi-scale transforms (W-MST) is proposed to detect delamination and inclusion defects of GFRP composites. Moreover, the strategy of weighted least square optimization (WLSO) is adopted to eliminate the effects of unregistered images. An exhaustive number of combinations (36 in total) of the proposed fusion algorithm, which include the selection of fusion rules for saliency map, wavelet decomposition levels and wavelet basis functions, have been quantitively compared using objective evaluation indices such as standard deviation (SD) and spatial frequency (SF) to quantify the improvement of detection effect in terms of contrast and resolution. Among them, there are five optimal combinations applicable to five pairs of different source images, and the averages of the SD and SF indicators of fused images have increased by 126% and 190% compared with the source images, respectively. The inspection efficacy of defects using the proposed fusion method has been analyzed visually, showing that the new approach can effectively accentuate the complementary advantages of THz and X-ray NDT methods, resulting in quantifiably improved defect inspections.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper presents a new method of analysis of results obtained using the Magnetic Recording Method (MRM), which was applied to inspect tensile stress-loaded ferromagnetic samples. The MRM method ...comprised a two-step procedure. In the first step, a strictly defined magnetic pattern is recorded on the samples using an array of permanent magnets, and then the original residual magnetization is measured. Next, the samples are subjected to static stress. In the second step, the residual magnetization measurement is repeated. Comparative analysis of the measurement results allows for an accurate and unambiguous assessment of applied stress in steel components. Moreover, the magnetization was measured again after three years to investigate the effect of time on magnetization patterns. The study confirms that the method is stable and has a negligible time dependence.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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