A guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to ...A guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to generate a guide wave using a piezoelectric element (PZT). However, the transverse wave-transducer using PZT needs to require a high viscosity couplant because the transverse wave cannot travel into typical liquid like water or oil. A guide wave inspection system that uses an electromagnetic ultrasonic transducer (EMAT) which does not require any couplant has then been developed to solve this trouble. First, a guide wave into a pipe, L, T and F-mode, can be transmitted and received by a polarized shear horizontal transverse wave propagating to the thickness direction when the vibration direction has been adjusted to the best direction. At next stage, the three EMATs for L, T and F-mode with different polarized vibration directions were piled up to improve the performance at the same position under the permanent magnet to inspect the pipe at the same condition. Next, the system with the EMATs can be confirmed to be able to detect three guide wave modes signal with enough intensity. Finally, the detection performance using the test pipes with any artificial defects has been done by the developed pipe inspection system, and any drilled holes and any notches can be detected. It is indicated that the developed system could be useful in real industrial field.展开更多
Metal pipes having an inner diameter of about 25 mm or less are frequently used as heat exchangers for power plants, gas pipes, and water pipes. However, erosion and corrosion due to long-term use may cause serious ac...Metal pipes having an inner diameter of about 25 mm or less are frequently used as heat exchangers for power plants, gas pipes, and water pipes. However, erosion and corrosion due to long-term use may cause serious accidents, such as steam leaks, resulting in economic loss and environmental pollution. Therefore, inspection of the entire length and thickness before shipping or monitoring during operation are important technologies. However, no inspection technology including the inside of the wall thickness has been developed. The purpose was to develop an ultrasonic probe that can inspect the inner and outer surfaces from the inside of the pipe at the same time. The developed ultrasonic probe is based on an electromagnetic ultrasonic transducer (EMAT) that does not require a couplant and is then easy to install in a pipe. The EMAT for the longitudinal and for the transverse vibration mode guided wave are connected in series in order to take into account the variety of defects. First, the EMAT was successfully developed for each mode. That is, it was conducted by using the magnetostrictive effect for the longitudinal mode type and by using the Lorentz force for the transverse mode type, and evaluated to improve the performance. The reflected signal from a notch defect was then evaluated in the state that each EMAT was connected in series using any artificial defects and found to be able to detect any notches with about 10% depth or about 15% circumferential length.展开更多
Purpose–This study aims to solve the problem of weld quality inspection,for the aluminum alloy profile welding structure of high-speed train body has complex internal shape and thin plate thickness(2–4 mm),the conve...Purpose–This study aims to solve the problem of weld quality inspection,for the aluminum alloy profile welding structure of high-speed train body has complex internal shape and thin plate thickness(2–4 mm),the conventional nondestructive testing method of weld quality is difficult to implement.Design/methodology/approach–In order to solve this problem,the ultrasonic creeping wave detection technology was proposed.The impact of the profile structure on the creeping wave detection was studied by designing profile structural test blocks and artificial simulation defect test blocks.The detection technology was used to test the actual welded test blocks,and compared with the results of X-ray test and destructive test(tensile test)to verify the accuracy of the ultrasonic creeping wave test results.Findings–It is indicated that that X-ray has better effect on the inspection of porosities and incomplete penetration defects.However,due to special detection method and protection,the detection speed is slow,which cannot meet the requirements of field inspection of the welding structure of aluminum alloy thin-walled profile for high-speed train body.It can be used as an auxiliary detection method for a small number of sampling inspection.The ultrasonic creeping wave can be used to detect the incomplete penetration welds with the equivalent of 0.25 mm or more,the results of creeping wave detection correspond well with the actual incomplete penetration defects.Originality/value–The results show that creeping wave detection results correspond well with the actual non-penetration defects and can be used for welding quality inspection of aluminum alloy thin-wall profile composite welding joints.It is recommended to use the echo amplitude of the 10 mm 30.2 mm 30.5 mm notch as the criterion for weld qualification.展开更多
The performance of Li||Sb-Sn liquid metal batteries(LMBs) is hindered by the corrosion of the Sb-Sn cathode on its current collector. Herein, a uniform, dense, and low-oxidized W coating was prepared by plasma sprayin...The performance of Li||Sb-Sn liquid metal batteries(LMBs) is hindered by the corrosion of the Sb-Sn cathode on its current collector. Herein, a uniform, dense, and low-oxidized W coating was prepared by plasma spraying, which can effectively resist the corrosion of the cathode and improve the cycle stability of the Li||Sb-Sn LMBs. For the first time, micro-CT nondestructive inspection is applied in the field of LMBs. The corrosion micromorphology and composition evolution of the SS304 matrix and Sb-Sn cathode with or without the plasma-sprayed W coating is obtained without disassembling the battery, which proves that the W coating can effectively protect the SS304 matrix. Our autonomous new LMB device for nondestructive inspection is universal and can be applied to different LMBs systems for advancing knowledge of corrosion mechanism and protection. This work guarantees the ability to directly visualize the inner critical positions in three dimensions and fills the knowledge gap in the field of LMB detection technology.展开更多
There exists model uncertainty of probability of detection for inspecting ship structures with nondestructive inspection techniques. Based on a comparison of several existing probability of detection (POD) models, a n...There exists model uncertainty of probability of detection for inspecting ship structures with nondestructive inspection techniques. Based on a comparison of several existing probability of detection (POD) models, a new probability of detection model is proposed for the updating of crack size distribution. Furthermore, the theoretical derivation shows that most existing probability of detection models are special cases of the new probability of detection model. The least square method is adopted for determining the values of parameters in the new POD model. This new model is also compared with other existing probability of detection models. The results indicate that the new probability of detection model can fit the inspection data better. This new probability of detection model is then applied to the analysis of the problem of crack size updating for offshore structures. The Bayesian updating method is used to analyze the effect of probability of detection models on the posterior distribution of a crack size. The results show that different probabilities of detection models generate different posterior distributions of a crack size for offshore structures.展开更多
The paper addresses the first eddy current benchmark problem proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC). The problem simulates the eddy current response to the presence of an axisym...The paper addresses the first eddy current benchmark problem proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC). The problem simulates the eddy current response to the presence of an axisymmetric circumferential defect in an Inconel-600 tube. All simulations employ the axisymmetric code of the electromagnetic field simulator Finite Element Method Magnetics. For three different frequencies of excitation, it is explained how the displacement of the detecting coil inside the tube leads to a variation in the impedance of the eddy current coil. Variations of the resistive and inductive components of the impedance with distance from the defect region are used to build the impedance trajectory for each frequency of analysis.展开更多
In recent years there has been a strong interest in thermoplastic polymers with self-healing behaviour, which after suffering mechanically-induced damage self-repair via energy-activated macromolecular rearrangements....In recent years there has been a strong interest in thermoplastic polymers with self-healing behaviour, which after suffering mechanically-induced damage self-repair via energy-activated macromolecular rearrangements. The use of film-shaped self-regenerating polymers in alternating layers with high-performance continuous fibre-reinforced thermosetting polymer matrix laminates is considered particularly attractive in the mitigation of impact damage in high-demanding components and structures, insofar as the self-healing films may at the same time toughen the base fibrous thermosetting matrix laminate composite while providing immediate or subsequent self-repairing according to the above mentioned mechanisms. In this work, mechanical flexural testing along with infrared thermography inspection is proposed for characterizing low temperature （typical of the altitudes in which modem civil and military aircrafts travel） transverse low-energy ballistic impact damage （commonly occurring under the above cited conditions） in thermoplastic ionomer films interleaving carbon-fibre reinforced epoxy matrix laminates, as well as to assess the degree of success of thermally-activated self-healing process of ionomeric phase by external heating sources. Preliminary mechanical results supported the self-healing hypothesis of impact damaged hybrid laminates, and exploratory thermography imaging of both the as-damaged and as-rejuvenated test coupons suggested that this nondestructive evaluation technique is sensitive enough to detect healing effects.展开更多
To accurately diagnose the aging condition of the vehicle-mounted high-voltage cable terminals under the combined electro-thermal stress,this paper proposes a terahertz frequency spectrum technology-based method.First...To accurately diagnose the aging condition of the vehicle-mounted high-voltage cable terminals under the combined electro-thermal stress,this paper proposes a terahertz frequency spectrum technology-based method.First,an electro-thermal aging platform is established in the laboratory to obtain the test samples of ethylene-propylene rubber(EPR)cable terminals with different aging gradients.Then,the degree of electro-thermal aging is characterized by frequency spectrum,absorption coefficient spectrum,absorption spectrum,refractive index and dielectric constant in the terahertz domain.Moreover,the micro-morphology and micro-area structure of the test samples under different aging gradients are also observed by scanning electron microscopy,and both the material and chemical properties are analyzed.The findings demonstrate that terahertz frequency spectra offer significant benefits in non-destructively detecting and identifying the insulation condition of vehicle cable terminals during electro-thermal aging.Laboratory tests confirm the feasibility of utilizing the terahertz frequency spectrum to assess the insulation aging state of EPR cable terminals,making it potentially applicable for on-site purposes.展开更多
X-ray detectors which convert X-ray irradiation into electrical signals play an important role in diverse applications including medical diagnosis,security examination,nondestructive inspection,personal X-ray dosimete...X-ray detectors which convert X-ray irradiation into electrical signals play an important role in diverse applications including medical diagnosis,security examination,nondestructive inspection,personal X-ray dosimeters and fundamental research[1–5].Recently,metal halide perovskites(MHP)have been developed as a promising family for X-ray detection contributing to their intrinsic advantages,e.g.,simple synthesis,efficient X-ray absorption and excellent semiconducting properties[5–10].展开更多
文摘A guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to generate a guide wave using a piezoelectric element (PZT). However, the transverse wave-transducer using PZT needs to require a high viscosity couplant because the transverse wave cannot travel into typical liquid like water or oil. A guide wave inspection system that uses an electromagnetic ultrasonic transducer (EMAT) which does not require any couplant has then been developed to solve this trouble. First, a guide wave into a pipe, L, T and F-mode, can be transmitted and received by a polarized shear horizontal transverse wave propagating to the thickness direction when the vibration direction has been adjusted to the best direction. At next stage, the three EMATs for L, T and F-mode with different polarized vibration directions were piled up to improve the performance at the same position under the permanent magnet to inspect the pipe at the same condition. Next, the system with the EMATs can be confirmed to be able to detect three guide wave modes signal with enough intensity. Finally, the detection performance using the test pipes with any artificial defects has been done by the developed pipe inspection system, and any drilled holes and any notches can be detected. It is indicated that the developed system could be useful in real industrial field.
文摘Metal pipes having an inner diameter of about 25 mm or less are frequently used as heat exchangers for power plants, gas pipes, and water pipes. However, erosion and corrosion due to long-term use may cause serious accidents, such as steam leaks, resulting in economic loss and environmental pollution. Therefore, inspection of the entire length and thickness before shipping or monitoring during operation are important technologies. However, no inspection technology including the inside of the wall thickness has been developed. The purpose was to develop an ultrasonic probe that can inspect the inner and outer surfaces from the inside of the pipe at the same time. The developed ultrasonic probe is based on an electromagnetic ultrasonic transducer (EMAT) that does not require a couplant and is then easy to install in a pipe. The EMAT for the longitudinal and for the transverse vibration mode guided wave are connected in series in order to take into account the variety of defects. First, the EMAT was successfully developed for each mode. That is, it was conducted by using the magnetostrictive effect for the longitudinal mode type and by using the Lorentz force for the transverse mode type, and evaluated to improve the performance. The reflected signal from a notch defect was then evaluated in the state that each EMAT was connected in series using any artificial defects and found to be able to detect any notches with about 10% depth or about 15% circumferential length.
基金supported by the National Natural Science Foundation of China(51705470).
文摘Purpose–This study aims to solve the problem of weld quality inspection,for the aluminum alloy profile welding structure of high-speed train body has complex internal shape and thin plate thickness(2–4 mm),the conventional nondestructive testing method of weld quality is difficult to implement.Design/methodology/approach–In order to solve this problem,the ultrasonic creeping wave detection technology was proposed.The impact of the profile structure on the creeping wave detection was studied by designing profile structural test blocks and artificial simulation defect test blocks.The detection technology was used to test the actual welded test blocks,and compared with the results of X-ray test and destructive test(tensile test)to verify the accuracy of the ultrasonic creeping wave test results.Findings–It is indicated that that X-ray has better effect on the inspection of porosities and incomplete penetration defects.However,due to special detection method and protection,the detection speed is slow,which cannot meet the requirements of field inspection of the welding structure of aluminum alloy thin-walled profile for high-speed train body.It can be used as an auxiliary detection method for a small number of sampling inspection.The ultrasonic creeping wave can be used to detect the incomplete penetration welds with the equivalent of 0.25 mm or more,the results of creeping wave detection correspond well with the actual incomplete penetration defects.Originality/value–The results show that creeping wave detection results correspond well with the actual non-penetration defects and can be used for welding quality inspection of aluminum alloy thin-wall profile composite welding joints.It is recommended to use the echo amplitude of the 10 mm 30.2 mm 30.5 mm notch as the criterion for weld qualification.
基金supported by the National Key R&D Program of China (No. 2018YFB0905600)。
文摘The performance of Li||Sb-Sn liquid metal batteries(LMBs) is hindered by the corrosion of the Sb-Sn cathode on its current collector. Herein, a uniform, dense, and low-oxidized W coating was prepared by plasma spraying, which can effectively resist the corrosion of the cathode and improve the cycle stability of the Li||Sb-Sn LMBs. For the first time, micro-CT nondestructive inspection is applied in the field of LMBs. The corrosion micromorphology and composition evolution of the SS304 matrix and Sb-Sn cathode with or without the plasma-sprayed W coating is obtained without disassembling the battery, which proves that the W coating can effectively protect the SS304 matrix. Our autonomous new LMB device for nondestructive inspection is universal and can be applied to different LMBs systems for advancing knowledge of corrosion mechanism and protection. This work guarantees the ability to directly visualize the inner critical positions in three dimensions and fills the knowledge gap in the field of LMB detection technology.
文摘There exists model uncertainty of probability of detection for inspecting ship structures with nondestructive inspection techniques. Based on a comparison of several existing probability of detection (POD) models, a new probability of detection model is proposed for the updating of crack size distribution. Furthermore, the theoretical derivation shows that most existing probability of detection models are special cases of the new probability of detection model. The least square method is adopted for determining the values of parameters in the new POD model. This new model is also compared with other existing probability of detection models. The results indicate that the new probability of detection model can fit the inspection data better. This new probability of detection model is then applied to the analysis of the problem of crack size updating for offshore structures. The Bayesian updating method is used to analyze the effect of probability of detection models on the posterior distribution of a crack size. The results show that different probabilities of detection models generate different posterior distributions of a crack size for offshore structures.
文摘The paper addresses the first eddy current benchmark problem proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC). The problem simulates the eddy current response to the presence of an axisymmetric circumferential defect in an Inconel-600 tube. All simulations employ the axisymmetric code of the electromagnetic field simulator Finite Element Method Magnetics. For three different frequencies of excitation, it is explained how the displacement of the detecting coil inside the tube leads to a variation in the impedance of the eddy current coil. Variations of the resistive and inductive components of the impedance with distance from the defect region are used to build the impedance trajectory for each frequency of analysis.
文摘In recent years there has been a strong interest in thermoplastic polymers with self-healing behaviour, which after suffering mechanically-induced damage self-repair via energy-activated macromolecular rearrangements. The use of film-shaped self-regenerating polymers in alternating layers with high-performance continuous fibre-reinforced thermosetting polymer matrix laminates is considered particularly attractive in the mitigation of impact damage in high-demanding components and structures, insofar as the self-healing films may at the same time toughen the base fibrous thermosetting matrix laminate composite while providing immediate or subsequent self-repairing according to the above mentioned mechanisms. In this work, mechanical flexural testing along with infrared thermography inspection is proposed for characterizing low temperature （typical of the altitudes in which modem civil and military aircrafts travel） transverse low-energy ballistic impact damage （commonly occurring under the above cited conditions） in thermoplastic ionomer films interleaving carbon-fibre reinforced epoxy matrix laminates, as well as to assess the degree of success of thermally-activated self-healing process of ionomeric phase by external heating sources. Preliminary mechanical results supported the self-healing hypothesis of impact damaged hybrid laminates, and exploratory thermography imaging of both the as-damaged and as-rejuvenated test coupons suggested that this nondestructive evaluation technique is sensitive enough to detect healing effects.
基金supported in part by the National Natural Science Foundation of China(52167018)Opening Foundation of the National Rail Transportation Electrification and Automation Engineering Technology ResearchCenter(NEEC-2022-B19).
文摘To accurately diagnose the aging condition of the vehicle-mounted high-voltage cable terminals under the combined electro-thermal stress,this paper proposes a terahertz frequency spectrum technology-based method.First,an electro-thermal aging platform is established in the laboratory to obtain the test samples of ethylene-propylene rubber(EPR)cable terminals with different aging gradients.Then,the degree of electro-thermal aging is characterized by frequency spectrum,absorption coefficient spectrum,absorption spectrum,refractive index and dielectric constant in the terahertz domain.Moreover,the micro-morphology and micro-area structure of the test samples under different aging gradients are also observed by scanning electron microscopy,and both the material and chemical properties are analyzed.The findings demonstrate that terahertz frequency spectra offer significant benefits in non-destructively detecting and identifying the insulation condition of vehicle cable terminals during electro-thermal aging.Laboratory tests confirm the feasibility of utilizing the terahertz frequency spectrum to assess the insulation aging state of EPR cable terminals,making it potentially applicable for on-site purposes.
基金supported by the National Natural Science Foundation of China(22435005,22193042,21921001,22125110,22122507,22201284,22305105,U21A2069)the Natural Science Foundation of Jiangxi Province(20224BAB213003,2024BAB25129)the Jiangxi Provincial Education Department Science and Technology Research Foundation(GJJ2200384).
文摘X-ray detectors which convert X-ray irradiation into electrical signals play an important role in diverse applications including medical diagnosis,security examination,nondestructive inspection,personal X-ray dosimeters and fundamental research[1–5].Recently,metal halide perovskites(MHP)have been developed as a promising family for X-ray detection contributing to their intrinsic advantages,e.g.,simple synthesis,efficient X-ray absorption and excellent semiconducting properties[5–10].
