Crack detection in an aerospace turbine disk is essential for aircraft-quality detection.With the unique circular stepped structure and superalloy material properties of aerospace turbine disk,it is difficult for the ...Crack detection in an aerospace turbine disk is essential for aircraft-quality detection.With the unique circular stepped structure and superalloy material properties of aerospace turbine disk,it is difficult for the traditional ultrasonic testing method to perform efficient and accurate testing.In this study,ultrasound phased array detection technology was applied to the non-destructive testing of aviation turbine disks:(i)A phased array ultrasonic c-scan device for detecting aerospace turbine disk cracks(PAUDA)was developed which consists of phased array ultrasonic,transducers,a computer,a displacement encoder,and a rotating scanner;(ii)The influence of the detection parameters include frequency,wave-type,and elements number of the ultrasonic phased array probe on the detection results on the near-surface and the far surface of the aerospace turbine disk is analyzed;(iii)Specimens with flat-bottom-hole(FBH)defects were scanned by the developed PAUDA and the results were analyzed and compared with the conventional single probe ultrasonic water immersion testing.The experiment shows that by using the ultrasonic phased array c-scan to scan the turbine disk the accuracy of the detection can be significantly improved which is of greater accuracy and higher efficiency than traditional immersion testing.展开更多
The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field dis...The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.展开更多
A diffuse acoustic field has been increasingly used to infer temporal changes in the structures,such as early dislo-cations and microcracking.This study explores three different techniques to characterise acoustic fie...A diffuse acoustic field has been increasingly used to infer temporal changes in the structures,such as early dislo-cations and microcracking.This study explores three different techniques to characterise acoustic field by using a single ultrasonic phased array.The first two techniques are proposed to measure spatial uniformity of wave field by examining differences in the integral of energy and the maximum energy respectively at multiple inspection loca-tions.The third one is developed to evaluate the degree of phase coherence between propagating waves transmitted sequentially by two neighbouring array elements.The efficacy of these techniques are investigated by examining their metrics on simulations and well-known samples.The results suggest that two selected metrics can be used to quantitatively estimate the diffuse field start time as well as the field size by comparing their value with the idealised diffuse state(15%for the energy integral metric,ηarea and 1 for the phase coherence metric,ηphase)and identifying the convergence start point.展开更多
Nonlinear ultrasonic imaging techniques in pulse-echo configuration have recently shown their potential to allow the effective separation of nonlinear and linear features in a nonlinear image.In this study,two ultraso...Nonlinear ultrasonic imaging techniques in pulse-echo configuration have recently shown their potential to allow the effective separation of nonlinear and linear features in a nonlinear image.In this study,two ultrasonic phased arrays are implemented to produce an image of elastic nonlinearity through the parallel-sequential subtraction of the coherently scattered components in the through-transmission acoustic field at the transmission or subharmonic frequency.In parallel mode,a physical focus at each pixel is achieved by firing the transmitters with a predefined delay law.In sequential mode,each transmitter is fired in sequence and all the receivers are employed to capture the data simultaneously.This full matrix captured data can be post-processed and focused synthetically at the target area.The images of parallel focusing and sequential focusing are expected to be linearly identical and hence any differences remained on the subtracted image can be related to the nonlinearities arising from the defects.Therefore,the imaging metric here is defined as the difference between parallel and sequentially focused amplitudes obtained from forward coherently scattered fields at each target point.Additionally,the negative influences due to the instrumentation nonlinearities are investigated by studying the remaining relative phase and amplitude at undamaged pixels.A compensation method is implemented to suppress these noises,significantly enhancing the selectivity of nonlinear scattering features.The proposed techniques are then implemented to monitor fatigue crack growth in order to explore the capability of these methods as measures of elastic nonlinearity induced by different sizes of small closed cracks.The promising results suggest that nonlinear imaging can be used to monitor crack growth and improve the detectability at early stages.展开更多
基金This work was funded by the National Natural Science Foundation of China[Grant Nos.11664027,11374134]The National Natural Science Foundation of Jiangxi Province[Grant No.20161BAB216101]+1 种基金Key Laboratory of Non-Destructive Testing and Monitoring Technology for High-Speed Transport Facilities of the Ministry of Industry and Information Technology,Nanjing University of Aeronautics and AstronauticsThe Key Laboratory of Nondestructive Testing of Ministry of Education Nanchang Hang Kong University,Nanchang,China.
文摘Crack detection in an aerospace turbine disk is essential for aircraft-quality detection.With the unique circular stepped structure and superalloy material properties of aerospace turbine disk,it is difficult for the traditional ultrasonic testing method to perform efficient and accurate testing.In this study,ultrasound phased array detection technology was applied to the non-destructive testing of aviation turbine disks:(i)A phased array ultrasonic c-scan device for detecting aerospace turbine disk cracks(PAUDA)was developed which consists of phased array ultrasonic,transducers,a computer,a displacement encoder,and a rotating scanner;(ii)The influence of the detection parameters include frequency,wave-type,and elements number of the ultrasonic phased array probe on the detection results on the near-surface and the far surface of the aerospace turbine disk is analyzed;(iii)Specimens with flat-bottom-hole(FBH)defects were scanned by the developed PAUDA and the results were analyzed and compared with the conventional single probe ultrasonic water immersion testing.The experiment shows that by using the ultrasonic phased array c-scan to scan the turbine disk the accuracy of the detection can be significantly improved which is of greater accuracy and higher efficiency than traditional immersion testing.
基金Supported by National Key R&D Program of China(Grant No.2016YFF0203000)State Key Program of National Natural Science Foundation of China(Grant No.11834008)+5 种基金National Natural Science Foundation of China(Grant Nos.11774167,61571222)Fundamental research funds for the Central Universities(Grant No.020414380001)State Key Laboratory of Acoustics,Chinese Academy of Science(Grant No.SKLA201809)Key Laboratory of Underwater Acoustic Environment,Chinese Academy of Sciences(Grant No.SSHJ-KFKT-1701)AQSIQ technology R&D program(Grant No.2017QK125)Innovative Talents Program of Far East NDT New Technology&Application Forum
文摘The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.
基金Supported by Anhui Provincial Natural Science Foundation of China(Grant No.2008085J24)Anhui Provincial Science and Technology Major Project of China(Grant No.201903a05020010)+2 种基金Young Talent Support Program of China Association for Science and Technology(Grant No.[2020]No.87)Doctoral Science and Technology Foundation of Hefei General Machinery Research Institute(Grant No.2019010381)Anhui Provincial Key Research and Development Plan of China(Grant No.202004a05020003).
文摘A diffuse acoustic field has been increasingly used to infer temporal changes in the structures,such as early dislo-cations and microcracking.This study explores three different techniques to characterise acoustic field by using a single ultrasonic phased array.The first two techniques are proposed to measure spatial uniformity of wave field by examining differences in the integral of energy and the maximum energy respectively at multiple inspection loca-tions.The third one is developed to evaluate the degree of phase coherence between propagating waves transmitted sequentially by two neighbouring array elements.The efficacy of these techniques are investigated by examining their metrics on simulations and well-known samples.The results suggest that two selected metrics can be used to quantitatively estimate the diffuse field start time as well as the field size by comparing their value with the idealised diffuse state(15%for the energy integral metric,ηarea and 1 for the phase coherence metric,ηphase)and identifying the convergence start point.
基金the Young Talent Support Program of China Association for Science and Technology(Grant No.[2020]No.87)the Science and Technology Major Project of Anhui Province(Grant No.201903a05020010)+2 种基金the Key Research and Development Plan of Anhui Province(Grant No.202004a05020003)the Anhui Provincial Natural Science Foundation(Grant No.2008085J24)the Doctoral Science and Technology Foundation of Hefei General Machinery Research Institute(Grant No.2019010381)。
文摘Nonlinear ultrasonic imaging techniques in pulse-echo configuration have recently shown their potential to allow the effective separation of nonlinear and linear features in a nonlinear image.In this study,two ultrasonic phased arrays are implemented to produce an image of elastic nonlinearity through the parallel-sequential subtraction of the coherently scattered components in the through-transmission acoustic field at the transmission or subharmonic frequency.In parallel mode,a physical focus at each pixel is achieved by firing the transmitters with a predefined delay law.In sequential mode,each transmitter is fired in sequence and all the receivers are employed to capture the data simultaneously.This full matrix captured data can be post-processed and focused synthetically at the target area.The images of parallel focusing and sequential focusing are expected to be linearly identical and hence any differences remained on the subtracted image can be related to the nonlinearities arising from the defects.Therefore,the imaging metric here is defined as the difference between parallel and sequentially focused amplitudes obtained from forward coherently scattered fields at each target point.Additionally,the negative influences due to the instrumentation nonlinearities are investigated by studying the remaining relative phase and amplitude at undamaged pixels.A compensation method is implemented to suppress these noises,significantly enhancing the selectivity of nonlinear scattering features.The proposed techniques are then implemented to monitor fatigue crack growth in order to explore the capability of these methods as measures of elastic nonlinearity induced by different sizes of small closed cracks.The promising results suggest that nonlinear imaging can be used to monitor crack growth and improve the detectability at early stages.