Pub Date : 2026-04-01Epub Date: 2025-12-08DOI: 10.1016/j.ndteint.2025.103623
Zhichao Li, Guichao Huang, Runjie Yang, Xuesong Wang, Chaoran Deng
Electromagnetic acoustic transducers (EMATs) suffer from inherently low transduction efficiency. Recent studies have demonstrated that the horizontal magnetic fields can significantly enhance the signal amplitude of Lorentz force-based EMATs. However, conventional analytical models primarily account for the effects of the vertical magnetic fields, while overlooking the excitation contribution of the horizontal magnetic fields, thereby limiting efforts to improve EMAT performance. In this work, the electromagnetic ultrasonic testing process using Rayleigh waves is systematically divided into three stages: excitation, propagation, and reception. Theoretical models are developed for each stage. Based on this framework, an analytical model incorporating both the vertical and horizontal magnetic fields is established. Experimental results from various coil configurations demonstrate that the proposed theoretical model can accurately compute the ultrasonic signals within the test specimen. Furthermore, the analytical model is employed to investigate the effect of magnet width on the amplitude and distortion level of the received signal. The findings reveal that when the magnet width is equal to the overall width of the coil, the received signal achieves the maximum amplitude with relatively low distortion.
{"title":"Analytical modeling and analysis of Rayleigh-wave EMATs considering both the horizontal and vertical magnetic fields","authors":"Zhichao Li, Guichao Huang, Runjie Yang, Xuesong Wang, Chaoran Deng","doi":"10.1016/j.ndteint.2025.103623","DOIUrl":"10.1016/j.ndteint.2025.103623","url":null,"abstract":"<div><div>Electromagnetic acoustic transducers (EMATs) suffer from inherently low transduction efficiency. Recent studies have demonstrated that the horizontal magnetic fields can significantly enhance the signal amplitude of Lorentz force-based EMATs. However, conventional analytical models primarily account for the effects of the vertical magnetic fields, while overlooking the excitation contribution of the horizontal magnetic fields, thereby limiting efforts to improve EMAT performance. In this work, the electromagnetic ultrasonic testing process using Rayleigh waves is systematically divided into three stages: excitation, propagation, and reception. Theoretical models are developed for each stage. Based on this framework, an analytical model incorporating both the vertical and horizontal magnetic fields is established. Experimental results from various coil configurations demonstrate that the proposed theoretical model can accurately compute the ultrasonic signals within the test specimen. Furthermore, the analytical model is employed to investigate the effect of magnet width on the amplitude and distortion level of the received signal. The findings reveal that when the magnet width is equal to the overall width of the coil, the received signal achieves the maximum amplitude with relatively low distortion.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103623"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145747413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-11-14DOI: 10.1016/j.ndteint.2025.103595
Jianxi Ding , Xin'an Yuan , Wei Li , Xiaokang Yin , Xiao Li , Dong Hu , Zichen Nie , Dehui Wang , Jianming Zhao
The alternating current field measurement (ACFM) is an excellent method for detecting cracks in underwater carbon steel structures. ACFM obtains crack information based on secondary electromagnetic field perturbation. The weak secondary electromagnetic field is insufficient for detecting subsurface and surface cracks. This study proposes a magnetic resistance perturbation testing (MRPT) method based on measured primary magnetic field in ACFM. Weak DC magnetization is employed to generate localized permeability perturbations surrounding surface and subsurface cracks. The permeability modifies the magnetic reluctance of carbon steel in the ACFM excitation field zone, leading to detectable amplitude variations in the primary magnetic field. The magnetic permeability disturbance transmits subsurface crack signatures to the surface detection zone and enhances the detectability of surface cracks. Being the spatial integration of permeability, the magnetic reluctance in the ACFM excitation zone effectively amplifies weak permeability disturbances of crack. This mechanism endows the MRPT method with enhanced sensitivity to both subsurface and surface cracks in any direction. Simulation and experiments on different cracks have been conducted to validate the efficiency of the MRPT method. The experimental results show that horizontal and vertical subsurface cracks with a depth of 11.5 mm can be detected with high sensitivity. The detection accuracy of surface cracks is improved.
{"title":"Magnetic resistance perturbation testing for high-sensitivity detection of subsurface and surface cracks in carbon steel","authors":"Jianxi Ding , Xin'an Yuan , Wei Li , Xiaokang Yin , Xiao Li , Dong Hu , Zichen Nie , Dehui Wang , Jianming Zhao","doi":"10.1016/j.ndteint.2025.103595","DOIUrl":"10.1016/j.ndteint.2025.103595","url":null,"abstract":"<div><div>The alternating current field measurement (ACFM) is an excellent method for detecting cracks in underwater carbon steel structures. ACFM obtains crack information based on secondary electromagnetic field perturbation. The weak secondary electromagnetic field is insufficient for detecting subsurface and surface cracks. This study proposes a magnetic resistance perturbation testing (MRPT) method based on measured primary magnetic field in ACFM. Weak DC magnetization is employed to generate localized permeability perturbations surrounding surface and subsurface cracks. The permeability modifies the magnetic reluctance of carbon steel in the ACFM excitation field zone, leading to detectable amplitude variations in the primary magnetic field. The magnetic permeability disturbance transmits subsurface crack signatures to the surface detection zone and enhances the detectability of surface cracks. Being the spatial integration of permeability, the magnetic reluctance in the ACFM excitation zone effectively amplifies weak permeability disturbances of crack. This mechanism endows the MRPT method with enhanced sensitivity to both subsurface and surface cracks in any direction. Simulation and experiments on different cracks have been conducted to validate the efficiency of the MRPT method. The experimental results show that horizontal and vertical subsurface cracks with a depth of 11.5 mm can be detected with high sensitivity. The detection accuracy of surface cracks is improved.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103595"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-18DOI: 10.1016/j.ndteint.2025.103626
Zenghua Liu , Mengqi Su , Xin Zhao , Tianxiang Kong , Yanhong Guo , Cuiping Huo , Cunfu He
Shear Horizontal (SH) guided waves play a crucial role in non-destructive testing and structural health monitoring. Particularly, the higher-order modes of SH waves are sensitive to variations in material thickness, making it useful for detecting material thinning, while their group velocities can be conveniently studied through frequency control. This research proposed a novel omnidirectional high-order SH mode electromagnetic acoustic transducer (OHSHM-EMAT), composed of 14 axially polarized sector-shaped magnets with alternating magnetic field orientations, complemented by a spiral coil configuration. The transducer effectively excites and receives high-order SH1 guided waves in aluminum plates using a circumferentially periodic permanent magnet array. A 3D finite element model of the OHSHM-EMAT was constructed, successfully demonstrating the excitation of SH1 guided waves. Optimal configuration parameters for the magnets and coil were determined through optimization. To validate the accuracy of the simulation results, performance verification experiments were conducted on aluminum plates. Experimental results confirmed that the OHSHM-EMAT can generate omnidirectional SH1 mode guided waves in aluminum materials while effectively suppressing the generation of SH0 mode guided waves.
{"title":"An omnidirectional high-order shear horizontal mode EMAT","authors":"Zenghua Liu , Mengqi Su , Xin Zhao , Tianxiang Kong , Yanhong Guo , Cuiping Huo , Cunfu He","doi":"10.1016/j.ndteint.2025.103626","DOIUrl":"10.1016/j.ndteint.2025.103626","url":null,"abstract":"<div><div>Shear Horizontal (SH) guided waves play a crucial role in non-destructive testing and structural health monitoring. Particularly, the higher-order modes of SH waves are sensitive to variations in material thickness, making it useful for detecting material thinning, while their group velocities can be conveniently studied through frequency control. This research proposed a novel omnidirectional high-order SH mode electromagnetic acoustic transducer (OHSHM-EMAT), composed of 14 axially polarized sector-shaped magnets with alternating magnetic field orientations, complemented by a spiral coil configuration. The transducer effectively excites and receives high-order SH<sub>1</sub> guided waves in aluminum plates using a circumferentially periodic permanent magnet array. A 3D finite element model of the OHSHM-EMAT was constructed, successfully demonstrating the excitation of SH<sub>1</sub> guided waves. Optimal configuration parameters for the magnets and coil were determined through optimization. To validate the accuracy of the simulation results, performance verification experiments were conducted on aluminum plates. Experimental results confirmed that the OHSHM-EMAT can generate omnidirectional SH<sub>1</sub> mode guided waves in aluminum materials while effectively suppressing the generation of SH<sub>0</sub> mode guided waves.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103626"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-01DOI: 10.1016/j.ndteint.2025.103620
Cristian A. Calistru , Ehsan Mohseni , Vedran Tunukovic , S. Gareth Pierce , David Lines , Charles N. MacLeod , Randika K.W. Vithanage , Iain Bomphray , Tobias Weis , Gavin Munro , Tom O'Hare
Resin infusion paired with Out of Autoclave (OoA) curing offers an alternative to infrastructure-heavy autoclave-based manufacturing. However, lower fibre volume fractions and increased porosity from uneven resin flow limit the adoption of OoA processes in safety-critical applications. Consequently, there is demand for in-situ monitoring tools to track resin progression and ensure full permeation. Prior methods, including optical fibres and electromagnetic sensors, can infer front position but are intrusive or hard to scale. This research investigates leaky Lamb waves generated by ultrasonic transducers embedded in the top lid of an infusion mould. To isolate wave-fluid interactions, liquid-only measurements in a 2.0 mm thick infusion box are collected, removing laminate heterogeneity and enabling acquisition of controllable consecutive measurements, enabling the development and validation of predictive models under well-defined conditions. Attenuation of the fundamental antisymmetric mode (A0) as resin reaches the sensing region was demonstrated through theoretical and simulation-based analysis, highlighting the potential of Ultrasonic Guided Waves (UGW) for real-time fluid tracking. A custom experimental setup enabled consistent repeatable measurements of an advancing liquid front. A parametric study investigated the effects of geometry and fluid on signal amplitude, determining sensor spacing for sensitivity and areal coverage. Ultrasonic measurements were correlated with time-stamped images of the resin front through a machine-vision algorithm. Several functional approximation methods were applied to estimate liquid position from ultrasonic data, capturing the general trends in flow behaviour. The models yielded robust predictions, with mean errors of 5–7 % of the sensor spacing, despite environmental variations and system nonlinearities contributing to data variability.
{"title":"A step towards ultrasonic guided wave monitoring for resin infusion front position estimation in composites manufacturing","authors":"Cristian A. Calistru , Ehsan Mohseni , Vedran Tunukovic , S. Gareth Pierce , David Lines , Charles N. MacLeod , Randika K.W. Vithanage , Iain Bomphray , Tobias Weis , Gavin Munro , Tom O'Hare","doi":"10.1016/j.ndteint.2025.103620","DOIUrl":"10.1016/j.ndteint.2025.103620","url":null,"abstract":"<div><div>Resin infusion paired with Out of Autoclave (OoA) curing offers an alternative to infrastructure-heavy autoclave-based manufacturing. However, lower fibre volume fractions and increased porosity from uneven resin flow limit the adoption of OoA processes in safety-critical applications. Consequently, there is demand for in-situ monitoring tools to track resin progression and ensure full permeation. Prior methods, including optical fibres and electromagnetic sensors, can infer front position but are intrusive or hard to scale. This research investigates leaky Lamb waves generated by ultrasonic transducers embedded in the top lid of an infusion mould. To isolate wave-fluid interactions, liquid-only measurements in a 2.0 mm thick infusion box are collected, removing laminate heterogeneity and enabling acquisition of controllable consecutive measurements, enabling the development and validation of predictive models under well-defined conditions. Attenuation of the fundamental antisymmetric mode (A0) as resin reaches the sensing region was demonstrated through theoretical and simulation-based analysis, highlighting the potential of Ultrasonic Guided Waves (UGW) for real-time fluid tracking. A custom experimental setup enabled consistent repeatable measurements of an advancing liquid front. A parametric study investigated the effects of geometry and fluid on signal amplitude, determining sensor spacing for sensitivity and areal coverage. Ultrasonic measurements were correlated with time-stamped images of the resin front through a machine-vision algorithm. Several functional approximation methods were applied to estimate liquid position from ultrasonic data, capturing the general trends in flow behaviour. The models yielded robust predictions, with mean errors of 5–7 % of the sensor spacing, despite environmental variations and system nonlinearities contributing to data variability.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103620"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-11-21DOI: 10.1016/j.ndteint.2025.103609
Jacob H. Brody , Prabhakaran Manogharan , Emma E. Peleg , Nathan W. Moore , Alper Erturk
Thermally sprayed coatings are extensively used in the energy and aerospace sectors to protect surfaces against wear, oxidation, corrosion, and for thermal insulation; therefore their characterization is vital to preserving and protecting key infrastructural capabilities. In this study, we conduct experiments to examine the feasibility of using nonlinear ultrasonic/acoustic techniques such as nonlinear resonance acoustic spectroscopy (NRAS) and second harmonic generation (SHG) to characterize thermally sprayed nickel coatings. Nonlinear elastic parameters have been proven to be highly sensitive to microstructural features in materials. This work characterizes the and nonlinearity parameters which are related to the degree of micro-damages (interlamellar gap/void structures) intrinsic to sprayed coatings. In this work, thermally sprayed nickel coatings are sprayed onto stainless steel substrates at two particle sizes (Ni 101 - fine powder and Ni 969 - coarse powder) and spray distances (101.6 and 203.2 mm stand-off distance). The sprayed coatings are separated from their substrates to determine if the nonlinearity parameters can effectively measure microstructural changes in these samples. The nonlinearity parameters measured independently from two different nonlinear ultrasonic/acoustic techniques show an increasing trend with increasing particle sizes and spray distances. Furthermore, NRAS measurements of coatings with and without the substrate indicate that the nonlinearity of thermally sprayed coatings can still be characterized on the thicker substrate. In addition to estimating the nonlinear parameters, porosity, hardness, wave speed and attenuation are also reported. Our results suggest that these nonlinear ultrasonic/acoustic techniques can be potentially used as an inspection and quality control tool for thermal spray coatings.
{"title":"Linear and nonlinear ultrasonic/acoustic characterization of thermally sprayed nickel coatings","authors":"Jacob H. Brody , Prabhakaran Manogharan , Emma E. Peleg , Nathan W. Moore , Alper Erturk","doi":"10.1016/j.ndteint.2025.103609","DOIUrl":"10.1016/j.ndteint.2025.103609","url":null,"abstract":"<div><div>Thermally sprayed coatings are extensively used in the energy and aerospace sectors to protect surfaces against wear, oxidation, corrosion, and for thermal insulation; therefore their characterization is vital to preserving and protecting key infrastructural capabilities. In this study, we conduct experiments to examine the feasibility of using nonlinear ultrasonic/acoustic techniques such as nonlinear resonance acoustic spectroscopy (NRAS) and second harmonic generation (SHG) to characterize thermally sprayed nickel coatings. Nonlinear elastic parameters have been proven to be highly sensitive to microstructural features in materials. This work characterizes the <span><math><mi>α</mi></math></span> and <span><math><mi>β</mi></math></span> nonlinearity parameters which are related to the degree of micro-damages (interlamellar gap/void structures) intrinsic to sprayed coatings. In this work, thermally sprayed nickel coatings are sprayed onto stainless steel substrates at two particle sizes (Ni 101 - fine powder and Ni 969 - coarse powder) and spray distances (101.6 and 203.2 mm stand-off distance). The sprayed coatings are separated from their substrates to determine if the nonlinearity parameters can effectively measure microstructural changes in these samples. The nonlinearity parameters measured independently from two different nonlinear ultrasonic/acoustic techniques show an increasing trend with increasing particle sizes and spray distances. Furthermore, NRAS measurements of coatings with and without the substrate indicate that the nonlinearity of thermally sprayed coatings can still be characterized on the thicker substrate. In addition to estimating the nonlinear parameters, porosity, hardness, wave speed and attenuation are also reported. Our results suggest that these nonlinear ultrasonic/acoustic techniques can be potentially used as an inspection and quality control tool for thermal spray coatings.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103609"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145622284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-01DOI: 10.1016/j.ndteint.2025.103618
Yigang Cheng , Wenze Shi , Chao Lu , Weiwei Chen , Yujia Zeng , Bo Hu
High-temperature alloy bolts used in aerospace engines face some issues, such as high ultrasonic attenuation coefficient and low electrical conductivity compared to traditional metal materials. Common measurement methods encounter problems, including the impact of piezoelectric ultrasonic coupling agents on acoustic time accuracy, film easy shedding of permanent mounted transducer system (PMTS), and low SNR in EMAT measurements. To date, there are limited high-precision ultrasonic measurement technologies available for the preload of bolt fasteners in high-temperature alloy materials such as GH4169. This research introduces a technique for measuring the time of flight (TOF) of ultrasonic waves within bolts using Laser-electromagnetic acoustic transducer (Laser-EMAT) technology and determines the preload of bolts employing either the mono-wave method or the bi-wave method. Utilizing numerical simulation and experimental validation, the study analyses the ultrasonic wave modes and their SNR under three laser-induced mechanisms: thermoelastic, ablation, and surface constraint, in GH4169 bolts. We establish a linear relationship between acoustic TOF and bolt preload and compare the measurement accuracy of the mono- and bi-wave methods under these three laser-induced mechanisms. The research showed that: Under the thermoelastic mechanism, the average relative errors of the mono-wave method and bi-wave method in measuring 10 kN and above loads were lower than 4.2 %, 4.9 %, respectively. Although the ablation mechanism can improve the SNR of longitudinal waves compared with the thermoelastic mechanism, the measurement accuracy decreases. Using the surface constraint mechanism with silver-grease as the coating material, the SNR of longitudinal waves was improved by 13 dB compared with the thermoelastic mechanism. The mono-wave method with second longitudinal waves achieved higher accuracy than the first longitudinal wave approach, showing under 1.6 % average error at loads of 5 kN and above. This study offers a novel high-precision testing approach for measuring the preload in aerospace engine high-temperature alloy bolts with a high level of ultrasonic wave attenuation.
{"title":"Research on Laser-EMAT measurement of preload in high-temperature alloy bolts for aerospace applications","authors":"Yigang Cheng , Wenze Shi , Chao Lu , Weiwei Chen , Yujia Zeng , Bo Hu","doi":"10.1016/j.ndteint.2025.103618","DOIUrl":"10.1016/j.ndteint.2025.103618","url":null,"abstract":"<div><div>High-temperature alloy bolts used in aerospace engines face some issues, such as high ultrasonic attenuation coefficient and low electrical conductivity compared to traditional metal materials. Common measurement methods encounter problems, including the impact of piezoelectric ultrasonic coupling agents on acoustic time accuracy, film easy shedding of permanent mounted transducer system (PMTS), and low SNR in EMAT measurements. To date, there are limited high-precision ultrasonic measurement technologies available for the preload of bolt fasteners in high-temperature alloy materials such as GH4169. This research introduces a technique for measuring the time of flight (TOF) of ultrasonic waves within bolts using Laser-electromagnetic acoustic transducer (Laser-EMAT) technology and determines the preload of bolts employing either the mono-wave method or the bi-wave method. Utilizing numerical simulation and experimental validation, the study analyses the ultrasonic wave modes and their SNR under three laser-induced mechanisms: thermoelastic, ablation, and surface constraint, in GH4169 bolts. We establish a linear relationship between acoustic TOF and bolt preload and compare the measurement accuracy of the mono- and bi-wave methods under these three laser-induced mechanisms. The research showed that: Under the thermoelastic mechanism, the average relative errors of the mono-wave method and bi-wave method in measuring 10 kN and above loads were lower than 4.2 %, 4.9 %, respectively. Although the ablation mechanism can improve the SNR of longitudinal waves compared with the thermoelastic mechanism, the measurement accuracy decreases. Using the surface constraint mechanism with silver-grease as the coating material, the SNR of longitudinal waves was improved by 13 dB compared with the thermoelastic mechanism. The mono-wave method with second longitudinal waves achieved higher accuracy than the first longitudinal wave approach, showing under 1.6 % average error at loads of 5 kN and above. This study offers a novel high-precision testing approach for measuring the preload in aerospace engine high-temperature alloy bolts with a high level of ultrasonic wave attenuation.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103618"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145747414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-05DOI: 10.1016/j.ndteint.2025.103622
Edmund Jones , Catrin M. Davies , Joseph Corcoran
A feasibility study into utilising Rayleigh surface waves for sizing regions of discontinuous creep crack damage in compact tension laboratory tests is presented. The method relies on the efficient Rayleigh surface to shear bulk wave mode conversion (and vice versa) at discontinuous surfaces, in a process referred to as ‘skipping’ in this paper. A Finite Element study is presented to demonstrate the skipping behaviour. In order to utilise the Rayleigh wave for creep crack growth measurements, a novel experimental procedure has been developed that enables in situ measurements at elevated temperature. The approach uses waveguides that transmit shear guided waves from ambient conditions to the sample which is inside a furnace. The waveguides are dry-coupled to the corner edges of the compact tension sample, the shear guided waves excite Rayleigh waves which then propagate around the crack tip. By monitoring the time-of-flight of the ultrasound the damaged region can be sized. Results of a creep crack growth experiment are shown and crack size estimates from x-ray computed tomography (XCT), direct current potential drop (DCPD) and the Rayleigh wave techniques are compared. The direct current potential drop measurements vastly underestimates the maximum extent of the damaged region, estimating 0.38 mm in contrast to the 1.40 mm measured by XCT, as the discontinuous defects are not an effective impediment to electrical current. The Rayleigh wave technique estimates a far more accurate 1.27 mm.
{"title":"A skipping Rayleigh wave technique for discontinuous creep crack sizing at high temperature","authors":"Edmund Jones , Catrin M. Davies , Joseph Corcoran","doi":"10.1016/j.ndteint.2025.103622","DOIUrl":"10.1016/j.ndteint.2025.103622","url":null,"abstract":"<div><div>A feasibility study into utilising Rayleigh surface waves for sizing regions of discontinuous creep crack damage in compact tension laboratory tests is presented. The method relies on the efficient Rayleigh surface to shear bulk wave mode conversion (and vice versa) at discontinuous surfaces, in a process referred to as ‘skipping’ in this paper. A Finite Element study is presented to demonstrate the skipping behaviour. In order to utilise the Rayleigh wave for creep crack growth measurements, a novel experimental procedure has been developed that enables in situ measurements at elevated temperature. The approach uses waveguides that transmit shear guided waves from ambient conditions to the sample which is inside a furnace. The waveguides are dry-coupled to the corner edges of the compact tension sample, the shear guided waves excite Rayleigh waves which then propagate around the crack tip. By monitoring the time-of-flight of the ultrasound the damaged region can be sized. Results of a creep crack growth experiment are shown and crack size estimates from x-ray computed tomography (XCT), direct current potential drop (DCPD) and the Rayleigh wave techniques are compared. The direct current potential drop measurements vastly underestimates the maximum extent of the damaged region, estimating 0.38 mm in contrast to the 1.40 mm measured by XCT, as the discontinuous defects are not an effective impediment to electrical current. The Rayleigh wave technique estimates a far more accurate 1.27 mm.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103622"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145747416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-02DOI: 10.1016/j.ndteint.2025.103613
Fuqiang Yang , Le Wang , Kuidong Huang , Shijie Chai , Zhixiang Li
Scatter severely degrades cone-beam computed tomography (CBCT) images, particularly in scans of high-density industrial components, where blur and shading artifacts hinder metrological evaluation. We propose an LSTM-residual network with an attention module to enhance cross-layer feature propagation. An attention module further improves convolutional neural network efficiency for image feature processing. The core approach estimates the scatter-to-primary ratio (SPR)—a metric reflecting scatter photon distribution influenced by material structures—using raw projection data to generate artifact-free images. By eliminating low-frequency scatter from preliminary observations, the network robustly mitigates scattering effects. Experimental validation with diverse industrial components—an aluminum stepped shaft, a titanium alloy sleeve, and a steel hollow cylinder—shows substantial image quality improvements. Comparative analysis reveals CNR improvements of 22 %, 33 %, and 52, and AG improvements of 46 %, 38 %, and 30 % for the three components, respectively. These results demonstrate the method's effectiveness in enhancing CBCT image clarity and reducing scatter-induced blur, highlighting its utility for industrial non-destructive testing.
{"title":"Application of a dense block connection network to SPR prediction for artifact reduction in X-ray computed tomography","authors":"Fuqiang Yang , Le Wang , Kuidong Huang , Shijie Chai , Zhixiang Li","doi":"10.1016/j.ndteint.2025.103613","DOIUrl":"10.1016/j.ndteint.2025.103613","url":null,"abstract":"<div><div>Scatter severely degrades cone-beam computed tomography (CBCT) images, particularly in scans of high-density industrial components, where blur and shading artifacts hinder metrological evaluation. We propose an LSTM-residual network with an attention module to enhance cross-layer feature propagation. An attention module further improves convolutional neural network efficiency for image feature processing. The core approach estimates the scatter-to-primary ratio (SPR)—a metric reflecting scatter photon distribution influenced by material structures—using raw projection data to generate artifact-free images. By eliminating low-frequency scatter from preliminary observations, the network robustly mitigates scattering effects. Experimental validation with diverse industrial components—an aluminum stepped shaft, a titanium alloy sleeve, and a steel hollow cylinder—shows substantial image quality improvements. Comparative analysis reveals CNR improvements of 22 %, 33 %, and 52, and AG improvements of 46 %, 38 %, and 30 % for the three components, respectively. These results demonstrate the method's effectiveness in enhancing CBCT image clarity and reducing scatter-induced blur, highlighting its utility for industrial non-destructive testing.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103613"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-11-21DOI: 10.1016/j.ndteint.2025.103599
Geng Yang , Haoran Li , Bin Gao , Xiaolong Lu , Junhong Qi , Dong Liu , Guiyun Tian , Xiaojie Xue , Xingcai Liu
Lift-off variability poses a significant challenge in electromagnetic thermography (ET) for detecting surface defects on rails, particularly under dynamic scanning conditions. To overcome this limitation, we propose a lift-off tolerant ET system based on a multiporous-cascaded excitation coil. This coil design enhances electromagnetic excitation and expands the effective heating footprint on the rail surface. Finite element simulations under various lift-off distances evaluate the coil's thermal response and excitation coverage. Compared to a conventional dual-turn elliptical coil, the proposed structure demonstrates superior heating intensity and spatial uniformity at large lift-off distances. Experimental validation at a scanning speed of 1 m/s with a 30 mm lift-off confirms the system's capability to detect multiple defect types with enhanced thermal contrast and signal robustness. These results validate the practical feasibility of the proposed system for dynamic rail inspection under large lift-off conditions.
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In this paper, we propose an advanced guided wave phased array (PA) ultrasonic imaging technique for improved defect detection in thin plate-like structures, leveraging Vector Coherence Factor (VCF)-weighted Total Focusing Method (TFM). In this approach, the guided wave is transmitted and received, particularly lamb waves, using the full matrix capture (FMC) scanning strategy for long-range inspection. A high-resolution image is obtained by virtually focusing on every point in the region of interest through TFM beamforming, which is weighted with VCF to improve the detectability of the defects in near-field, dead-zone, and far fields. However, in long-range inspections using Lamb waves, employing the FMC-TFM technique reduces the signal-to-noise ratio (SNR) in the received signals and lowers image resolution due to beam spreading and their inherent dispersive nature. Therefore, we implemented the VCF to weight the TFM beamforming process. VCF-TFM utilizes both amplitude and instantaneous phase information by analyzing received signals as complex vectors. Specifically, VCF evaluates coherence by analyzing the received signals as vectors in the complex domain, effectively enhancing phase-consistent defect reflections while suppressing incoherent background noise. The effectiveness of the proposed technique is experimentally validated on long stainless steel plate specimens containing multiple defects located in the near-field, far-field, and dead-zone regions. The results demonstrate that the proposed VCF-TFM approach significantly improves SNR and image resolution compared to conventional amplitude-based TFM techniques, enabling more accurate and reliable defect characterization in thin plate-like structures.
{"title":"Phased array guided wave imaging with Vector Coherence Factor for thin-walled structures","authors":"Kaushal Bachhav , Thulsiram Gantala , Krishnan Balasubramaniam","doi":"10.1016/j.ndteint.2025.103598","DOIUrl":"10.1016/j.ndteint.2025.103598","url":null,"abstract":"<div><div>In this paper, we propose an advanced guided wave phased array (PA) ultrasonic imaging technique for improved defect detection in thin plate-like structures, leveraging Vector Coherence Factor (VCF)-weighted Total Focusing Method (TFM). In this approach, the guided wave is transmitted and received, particularly lamb waves, using the full matrix capture (FMC) scanning strategy for long-range inspection. A high-resolution image is obtained by virtually focusing on every point in the region of interest through TFM beamforming, which is weighted with VCF to improve the detectability of the defects in near-field, dead-zone, and far fields. However, in long-range inspections using Lamb waves, employing the FMC-TFM technique reduces the signal-to-noise ratio (SNR) in the received signals and lowers image resolution due to beam spreading and their inherent dispersive nature. Therefore, we implemented the VCF to weight the TFM beamforming process. VCF-TFM utilizes both amplitude and instantaneous phase information by analyzing received signals as complex vectors. Specifically, VCF evaluates coherence by analyzing the received signals as vectors in the complex domain, effectively enhancing phase-consistent defect reflections while suppressing incoherent background noise. The effectiveness of the proposed technique is experimentally validated on long stainless steel plate specimens containing multiple defects located in the near-field, far-field, and dead-zone regions. The results demonstrate that the proposed VCF-TFM approach significantly improves SNR and image resolution compared to conventional amplitude-based TFM techniques, enabling more accurate and reliable defect characterization in thin plate-like structures.</div></div>","PeriodicalId":18868,"journal":{"name":"Ndt & E International","volume":"159 ","pages":"Article 103598"},"PeriodicalIF":4.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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