Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial app...Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial applications.This paper describes the basic principles of PA technology for NDT/E and its applications in recent years.PA technology for NDT/E includes the use of a modulated continuous-wave laser and a pulsed laser for PA wave excitation,PA-generated ultrasonic waves,and all-optical PA wave excitation and detection.PA technology for NDT/E has demonstrated broad applications,including the imaging of railway cracks and defects,the imaging of Li metal batteries,the measurements of the porosity and Young’s modulus,the detection of defects and damage in silicon wafers,and a visualization of underdrawings in paintings.展开更多
A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil.It is fre-quently observed in an eddy current(EC)array probe.In this work,a tilted non-coaxial driver-pickup ...A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil.It is fre-quently observed in an eddy current(EC)array probe.In this work,a tilted non-coaxial driver-pickup probe above a multilayered conducting plate is analytically modeled with spatial transformation for eddy current nondestructive evalua-tion.Basically,the core of the formulation is to obtain the projection of magnetic vector potential(MVP)from the driver coil onto the vector along the tilted pickup coil,which is divided into two key steps.The first step is to make a projection of MVP along the pickup coil onto a horizontal plane,and the second one is to build the relationship between the pr,ojected MVP and the MVP along the driver coil.Afterwards,an analytical model for the case of a layered plate is established with the reflection and transmission theory of electromagnetic fields.The calculated values from the resulting model indicate good agreement with those from the finite element model(FEM)and experiments,which validates the developed analytical model.展开更多
The use of terahertz time-domain spectroscopy(THz-TDS)for the nondestructive testing and evaluation(NDT&E)of materials and structural systems has attracted significant attention over the past two decades due to it...The use of terahertz time-domain spectroscopy(THz-TDS)for the nondestructive testing and evaluation(NDT&E)of materials and structural systems has attracted significant attention over the past two decades due to its superior spatial resolution and capabilities of detecting and characterizing defects and structural damage in non-conducting materials.In this study,the THz-TDS system is used to detect,localize and evaluate hidden multi-delamination defects(i.e.,a three-level multi-delamination system)in multilayered GFRP composite laminates.To obtain accurate results,a wavelet shrinkage de-noising algorithm is used to remove the noise from the measured time-of-flight(TOF)signals.The thickness and location of each delamination defect in the z-direction(i.e.,through-the-thickness direction)are calculated from the de-noised TOF signals considering the interaction between the pulsed THz waves and the different interfaces in the GFRP composite laminates.A comparison between the actual and the measured thickness values of the delamination defects before and after the wavelet shrinkage denoising process indicates that the latter provides better results with less than 3.712%relative error,while the relative error of the non-de-noised signals reaches 16.388%.Also,the power and absorbance levels of the THz waves at every interface with different refractive indices in the GFRP composite laminates are evaluated based on analytical and experimental approaches.The present study provides an adequate theoretical analysis that could help NDT&E specialists to estimate the maximum thickness of GFRP composite materials and/or structures with different interfaces that can be evaluated by the THz-TDS.Also,the accuracy of the obtained results highlights the capabilities of the THz-TDS for the NDT&E of multilayered GFRP composite laminates.展开更多
High frequency ultrasonic nondestructive testing was conducted using a direct contact method for SUS306 stainless steel treated by high temperature and fracture tensile tests. Reflected ultrasonic echoes were analyzed...High frequency ultrasonic nondestructive testing was conducted using a direct contact method for SUS306 stainless steel treated by high temperature and fracture tensile tests. Reflected ultrasonic echoes were analyzed. The relationships between the ultrasonic attenuation coefficient, strength of backscattering wave and the elongation at break of the samples were obtained. The damages were evaluated by using these results together with the analysis of microstructure and mechanics of the tested material.展开更多
Thermal barrier coatings(TBCs)in gas turbine engines are used in expressly harsh environments;thus,assessing TBC integrity status is critical for safety and reliability.However,traditional periodic maintenance involve...Thermal barrier coatings(TBCs)in gas turbine engines are used in expressly harsh environments;thus,assessing TBC integrity status is critical for safety and reliability.However,traditional periodic maintenance involves visual inspections of the TBCs,requiring the gas turbine to be decommissioned and partially dismantled.Most importantly,tiny defects or internal damages that easily cause coating failure cannot be identified.In this work,a new nondestructive evaluation(NDE)technique of TBCs based on quantum dot(QD)anion exchange is first explored internationally.By exchanging anions between the Cl ions and the CsPbBr_(3) QDs,the degrees of salt corrosion of the TBCs are evaluated.The resultant NDE technique shows that the colour of the TBCs obviously changes from green to blue,accompanied by a large blueshift(~100 nm)of the photoluminescence(PL)peak position.In addition,the relationship between the PL peak position and coating thermophysical properties indicates that the precision of this NDE technique may easily identify theμm-level of the thermal growth oxide(TGO)changes inside the TBCs.展开更多
Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the ...Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the modulus of rupture (MOR) of finger-jointed lumber specimens made with four kinds of Eucalyptus (Eucalyptus. citriodora, E. exserta, E. grandis x E. urophylla and E. grandis). Dynamic MOE was calculated from frequency and time obtained from forced vibrations and sounds induced in the four species of finger-jointed specimens. It was found that correlation coefficients between density and static MOE and dynamic MOE were statistically significant at the 0.01 level. And it was also found that the three nondestructive techniques can provide rapid and accurate means to determine the MOE, and the dynamic MOE was more accurate to predict static MOE than density. But the correlation coefficient between dynamic MOE, static MOE and MOR were lower than results reported by other researchers for solid wood, and were not statistically significant. It can be concluded that the three nondestructive techniques are useful for evaluating the MOE, but not suitable for predicting the MOR of finger-jointed.展开更多
This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from delaminations.The proposed technique ta...This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from delaminations.The proposed technique takes advantage of the fact that the IE compression wave is not a propagating wave,but it is the 1st order symmetrical(S1)mode Lamb wave at zero group velocity(S1-ZGV).Therefore,it searches the phase spectra of the data collected by multiple sensors to locate the frequency corresponding to the lowest phase difference.As a result,the technique reduces the effect of propagating waves,including the direct acoustic wave and ambient noise.It is named the Constant Phase IE(CPIE).The performance of the CPIE is experimentally compared with the regular amplitude spectrum-based IE technique and two other multisensor IE techniques.The CPIE shows a performance advantage,especially in a noisy environment.展开更多
6SGa decays to the excited states of aSzn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolut...6SGa decays to the excited states of aSzn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the 69Ga(n,2n) 6SGa reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is (2.72±0.16)%.展开更多
基金S.-L.Chen acknowledges funding from the National Natural Science Foundation of China,No.61775134C.Tian acknowledges funding from the National Natural Science Foundation of China,No.61705216the Anhui Science and Technology Department,No.18030801138.
文摘Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial applications.This paper describes the basic principles of PA technology for NDT/E and its applications in recent years.PA technology for NDT/E includes the use of a modulated continuous-wave laser and a pulsed laser for PA wave excitation,PA-generated ultrasonic waves,and all-optical PA wave excitation and detection.PA technology for NDT/E has demonstrated broad applications,including the imaging of railway cracks and defects,the imaging of Li metal batteries,the measurements of the porosity and Young’s modulus,the detection of defects and damage in silicon wafers,and a visualization of underdrawings in paintings.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61701500,51677187,and 51465024)
文摘A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil.It is fre-quently observed in an eddy current(EC)array probe.In this work,a tilted non-coaxial driver-pickup probe above a multilayered conducting plate is analytically modeled with spatial transformation for eddy current nondestructive evalua-tion.Basically,the core of the formulation is to obtain the projection of magnetic vector potential(MVP)from the driver coil onto the vector along the tilted pickup coil,which is divided into two key steps.The first step is to make a projection of MVP along the pickup coil onto a horizontal plane,and the second one is to build the relationship between the pr,ojected MVP and the MVP along the driver coil.Afterwards,an analytical model for the case of a layered plate is established with the reflection and transmission theory of electromagnetic fields.The calculated values from the resulting model indicate good agreement with those from the finite element model(FEM)and experiments,which validates the developed analytical model.
基金National Natural Science Foundation of China(Grant Nos.52275096,52005108,52275523)Fuzhou-Xiamen-Quanzhou National Independent Innovation Demonstration Zone High-end Equipment Vibration and Noise Detection and Fault Diagnosis Collaborative Innovation Platform ProjectFujian Provincial Major Research Project(Grant No.2022HZ024005)。
文摘The use of terahertz time-domain spectroscopy(THz-TDS)for the nondestructive testing and evaluation(NDT&E)of materials and structural systems has attracted significant attention over the past two decades due to its superior spatial resolution and capabilities of detecting and characterizing defects and structural damage in non-conducting materials.In this study,the THz-TDS system is used to detect,localize and evaluate hidden multi-delamination defects(i.e.,a three-level multi-delamination system)in multilayered GFRP composite laminates.To obtain accurate results,a wavelet shrinkage de-noising algorithm is used to remove the noise from the measured time-of-flight(TOF)signals.The thickness and location of each delamination defect in the z-direction(i.e.,through-the-thickness direction)are calculated from the de-noised TOF signals considering the interaction between the pulsed THz waves and the different interfaces in the GFRP composite laminates.A comparison between the actual and the measured thickness values of the delamination defects before and after the wavelet shrinkage denoising process indicates that the latter provides better results with less than 3.712%relative error,while the relative error of the non-de-noised signals reaches 16.388%.Also,the power and absorbance levels of the THz waves at every interface with different refractive indices in the GFRP composite laminates are evaluated based on analytical and experimental approaches.The present study provides an adequate theoretical analysis that could help NDT&E specialists to estimate the maximum thickness of GFRP composite materials and/or structures with different interfaces that can be evaluated by the THz-TDS.Also,the accuracy of the obtained results highlights the capabilities of the THz-TDS for the NDT&E of multilayered GFRP composite laminates.
基金supported by the National Natural Science Foundation of China (Grant No.60472102)the Innovative Program of Shanghai Municipal Education Commission (Grant No.07ZZ03)
文摘High frequency ultrasonic nondestructive testing was conducted using a direct contact method for SUS306 stainless steel treated by high temperature and fracture tensile tests. Reflected ultrasonic echoes were analyzed. The relationships between the ultrasonic attenuation coefficient, strength of backscattering wave and the elongation at break of the samples were obtained. The damages were evaluated by using these results together with the analysis of microstructure and mechanics of the tested material.
基金support form the Science and Technology Innovation Program of Hunan Province(No.2022RC1098)the Hunan Provincial Natural Science Foundation of China(Nos.2023JJ30563,2019JJ50565)+6 种基金the Scientific Research Fund of Hunan Provincial Education Department(Nos.22A0580,18A461)the Scientific Research Start-up Fund for High-level Talents in Xiangnan Universitysupported by the National Natural Science Foundation of China(Nos.51801034,52172067)the Natural Science Foundation of Guangdong Province(Nos.2021B1515020038,2020B1515020036)the Guangdong Special Support Program(No.2019BT02C629)supported by the Scientific Research Fund of Hunan Provincial Education Department(No.19C1706)the Scientific Research Fund of Chenzhou(No.zdyf201907).
文摘Thermal barrier coatings(TBCs)in gas turbine engines are used in expressly harsh environments;thus,assessing TBC integrity status is critical for safety and reliability.However,traditional periodic maintenance involves visual inspections of the TBCs,requiring the gas turbine to be decommissioned and partially dismantled.Most importantly,tiny defects or internal damages that easily cause coating failure cannot be identified.In this work,a new nondestructive evaluation(NDE)technique of TBCs based on quantum dot(QD)anion exchange is first explored internationally.By exchanging anions between the Cl ions and the CsPbBr_(3) QDs,the degrees of salt corrosion of the TBCs are evaluated.The resultant NDE technique shows that the colour of the TBCs obviously changes from green to blue,accompanied by a large blueshift(~100 nm)of the photoluminescence(PL)peak position.In addition,the relationship between the PL peak position and coating thermophysical properties indicates that the precision of this NDE technique may easily identify theμm-level of the thermal growth oxide(TGO)changes inside the TBCs.
基金This research is supported by ITTO Project PD 69/01 Rev.2(I) "Improved and diversified use of tropical plantation timber in China tosupplement diminishing supplies from natural forests".
文摘Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the modulus of rupture (MOR) of finger-jointed lumber specimens made with four kinds of Eucalyptus (Eucalyptus. citriodora, E. exserta, E. grandis x E. urophylla and E. grandis). Dynamic MOE was calculated from frequency and time obtained from forced vibrations and sounds induced in the four species of finger-jointed specimens. It was found that correlation coefficients between density and static MOE and dynamic MOE were statistically significant at the 0.01 level. And it was also found that the three nondestructive techniques can provide rapid and accurate means to determine the MOE, and the dynamic MOE was more accurate to predict static MOE than density. But the correlation coefficient between dynamic MOE, static MOE and MOR were lower than results reported by other researchers for solid wood, and were not statistically significant. It can be concluded that the three nondestructive techniques are useful for evaluating the MOE, but not suitable for predicting the MOR of finger-jointed.
文摘This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from delaminations.The proposed technique takes advantage of the fact that the IE compression wave is not a propagating wave,but it is the 1st order symmetrical(S1)mode Lamb wave at zero group velocity(S1-ZGV).Therefore,it searches the phase spectra of the data collected by multiple sensors to locate the frequency corresponding to the lowest phase difference.As a result,the technique reduces the effect of propagating waves,including the direct acoustic wave and ambient noise.It is named the Constant Phase IE(CPIE).The performance of the CPIE is experimentally compared with the regular amplitude spectrum-based IE technique and two other multisensor IE techniques.The CPIE shows a performance advantage,especially in a noisy environment.
文摘6SGa decays to the excited states of aSzn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the 69Ga(n,2n) 6SGa reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is (2.72±0.16)%.