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Determination of ultrasonic velocity and attenuation by wavelet analysis of echo waveform
N DT Abstracts current method where the frequency was changed in steps of I kHz; output signal from the coil were processed by a phase detection technique and displayed on a complex plane as a trajectory. By comparing the trajectory of a nondegraded material with that of a degraded material, degradation was evaluated quantitatively. Drawing such trajectory enabled us to capture the eddy current behavior totally. Increase in averaged radius of trajectory can be regarded as the increase in magnetic permeability of the material and decrease in averaged phase angle as the increase in electric conductivity. It was shown that fatigue brought about the increase in averaged phase angle, therefore the decrease in electric conductivity; and neutron irradiation embrittlement, the decrease in averaged phase angle, therefore the increase in electric conductivity.
In this study, nondestructive evaluation methods of deterioration in mortar and at interfaces between coarse aggregate and mortar were investigated. Concrete specimens subject to freeze-thaw damage and prior-loading were prepared, and the degrees of deterioration in these specimens were evaluated quantitatively through compressive tests and cross-sectional observation. Based on these results, the applicabilities of nondestructive testing methods, particularly, ultrasonics and acousto-ultrasonics (AU), for the evaluation of material deterioration in concrete were examined. The results were summarized as follows: 1) The deterioration at interfaces between coarse aggregate and mortar was mainly progressed in concrete subject to prior-loading, and freeze-thaw damage additionally caused the deterioration in mortar. 2) The velocity of ultrasonic pulse could be utilized to evaluate the degree of material deterioration in case that both interfaces and mortar were deteriorated. However, it could not be used in the case of deterioration occurring only at interfaces. In the latter case, the degree of deterioration could be evaluated by using the frequency distribution of the received wave obtained from AU testing.
Journal o f J S N D I , Vol. 46, No. 3 p. 197
Yatsushiro, K.; Hihara, M.; Tagawa, K.; Kuramoto, M. Thermal fatigue of nitrided hot working die steel (SKD61) Thermal properties of a nitrided layer on hot working die steel (SKD61) have been investigated in a heating test. X-ray stress constants for differently nitrided material have been measured. The results obtained are as follows:
Journal o f J S N D I , Vol. 46, No. 4 p. 281
(1) X-ray stress constant of a nitrided specimen A is KA(103) = --648 MPa/deg. with ~-Fe2_3N103 diffraction. For specimen B, the constant is K~003) = -920 MPa/deg. with e-Fe3N103 diffraction and KB(200)=-365MPa/deg. with e-Fe3N200 diffraction of CrKc~, respectively. Residual stresses ~rR calculated by using the measured stress constant KA(103), KB(103) and KB(200) are O'RA(103) -358 MPa, CrRB(103) = 342 MPa, and aRB(200) = 178 MPa, respectively. (2) In the thermal fatigue test, the peak intensity of e-Fez_aN103 diffraction was reduced with increasing testing cycles. It shows that the nitrided layer was decomposed by heating during the test. (3) Nitrided specimens showed a decrease of heat resistance. The oxidation of a nitrided layer begins at 723 K (450°C) which was examined by weight, X-ray diffraction analysis and microphotographic observations.
lhara, L; Koguchi, H.; Aizawa, T.; Kihara, J.; Iwazumi, N. Determination of thicknesses of multilayered coatings by surface acoustic wave - - 2nd report, an experimental verification In a previous paper of this series, we have proposed an inversion technique for estimating the thicknesses of a multilayered coating material. The inversion is based on the measurement and analysis of the dispersion curve of the surface wave velocity. In this paper an experiment is performed to confirm the validity of the inversion technique. A two-layered coating specimen (Al/Cr/glass) was made by depositing Cr and AI films onto a glass substrate using the D.C. magnetron sputtering technique. The dispersion curve is obtained by measuring the reflection coefficients of A1/Cr/glass using an ultrasonic spectrometer. The inversions are then applied to the identification of each layer thickness. The determined thicknesses agree well with results obtained by a stylus profiling technique. Thus, it is verified that the present inversion provides an effective means of accurately determining the thicknesses of a multilayered coating material.
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Journal o f J S N D I , Vol. 46, No. 3 p. 206
Inoue, H.; Kishimoto, K.; Nakanishi, T.; Hori, J.; Arai, M.; Shibuya, T. Determination of ultrasonic velocity and attenuation by wavelet analysis of echo waveform
Journal o f J S N D I , Vol. 46, No. 4 p. 296
Wavelet transform was applied for time-frequency analysis of waveforms obtained by an ultrasonic pulse-echo technique. The timefrequency analysis provides time variation of each frequency component involved in a waveform, which makes it possible to evaluate the ultrasonic velocity and attenuation at each frequency. In this paper, the practical accuracy of this method was examined through evaluation of ultrasonic velocity and attenuation of PMMA. In addition, the method was applied to ultrasonic evaluation of creepfatigue damage in SUS316 stainless steel.
Kato, K.; Ooka, N. Study on image quality of radiograph in radiographic examination for circumferential welded joint (Report 1) - basic study on scattered radiation in double wall exposure technique Wire type Image Quality Indicators (I.Q.I.) are usually used for the evaluation of the image quality of radiographs in radiographic examinations specified in the Japanese Industrial Standard (JIS). The relationship between the sensitivity of the Image Quality Indicator and the radiographic contrast in single wall exposure technique has already been well understood. However, the relationship in double wall exposure technique is still under discussion. As a result of the fundamental experiments using flat plates, it was found in this study that the image quality of radiograph depends on the ratio of scattered X-rays generated in the focus side test plate to transmitted X-rays, and that the ratio varies in inverse proportion to the distance between the flat plates. It was also shown that the simulation method based on the Compton Effect is effective in obtaining the ratio of scattered to transmitted X-rays in the double wall exposure technique for a pipe of more than 100 mm diameter.
Journal o f J S N D I , Vol. 46, No. 3 p. 223
Ihara, I.; Koguchi, H.; Aizawa, T.; Kihara, J.; Iwazumi, N. Determination of thicknesses of multilayered coatings by surface acoustic wave - - 1st report, utilization of inversion technique An inverse technique using surface acoustic wave (SAW) spectroscopy is applied to the nondestructive estimation of each layer thickness of a multilayered coating material. The inverse problem is formulated as an optimization problem of minimizing the differences between SAW dispersion curves obtained experimentally and numerically, where the dispersion curves are determined by analyzing the ultrasonic reflectivity of the layered material measured or calculated using the assumed layer thicknesses. First, the stability and accuracy of the solution in the inverse problem are discussed. Secondly, inverse analyses using the optimization procedure with the complex method are numerically simulated for a few sample problems. As a result, it is confirmed that the present inversion technique can be a promising way for quantitative estimation of each layer thickness of a multilayered coating material.
Journal o f J S N D I , Vol. 46, No. 4 p. 293
Kato, M.; Sato, T.; Kameyama, K.; Kosugi, Y. Evaluation of stress states in metals using stochastic model for deformation A stochastic model for deformation has been proposed to evaluate stress states in metals. The dependence of ultrasonic velocity on stress in metals can be applied to stress measurements and material characterization. The ultrasonic velocity propagating in the metal is described by higher-order effective elastic/elastic-plastic coefficients. The contribution of the deformation in the metal to acoustoelasticity is
Journal o f J S N D I , Vol. 46, No. 3 p. 223
lwanami, M.; Kamada, T.; Nagataki, S. The applicability of nondestructive testing methods to the evaluation of material deterioration in concrete
406
In this study, nondestructive evaluation methods of deterioration in mortar and at interfaces between coarse aggregate and mortar were investigated. Concrete specimens subject to freeze-thaw damage and prior-loading were prepared, and the degrees of deterioration in these specimens were evaluated quantitatively through compressive tests and cross-sectional observation. Based on these results, the applicabilities of nondestructive testing methods, particularly, ultrasonics and acousto-ultrasonics (AU), for the evaluation of material deterioration in concrete were examined. The results were summarized as follows: 1) The deterioration at interfaces between coarse aggregate and mortar was mainly progressed in concrete subject to prior-loading, and freeze-thaw damage additionally caused the deterioration in mortar. 2) The velocity of ultrasonic pulse could be utilized to evaluate the degree of material deterioration in case that both interfaces and mortar were deteriorated. However, it could not be used in the case of deterioration occurring only at interfaces. In the latter case, the degree of deterioration could be evaluated by using the frequency distribution of the received wave obtained from AU testing.
Journal o f J S N D I , Vol. 46, No. 3 p. 197
Yatsushiro, K.; Hihara, M.; Tagawa, K.; Kuramoto, M. Thermal fatigue of nitrided hot working die steel (SKD61) Thermal properties of a nitrided layer on hot working die steel (SKD61) have been investigated in a heating test. X-ray stress constants for differently nitrided material have been measured. The results obtained are as follows:
Journal o f J S N D I , Vol. 46, No. 4 p. 281
(1) X-ray stress constant of a nitrided specimen A is KA(103) = --648 MPa/deg. with ~-Fe2_3N103 diffraction. For specimen B, the constant is K~003) = -920 MPa/deg. with e-Fe3N103 diffraction and KB(200)=-365MPa/deg. with e-Fe3N200 diffraction of CrKc~, respectively. Residual stresses ~rR calculated by using the measured stress constant KA(103), KB(103) and KB(200) are O'RA(103) -358 MPa, CrRB(103) = 342 MPa, and aRB(200) = 178 MPa, respectively. (2) In the thermal fatigue test, the peak intensity of e-Fez_aN103 diffraction was reduced with increasing testing cycles. It shows that the nitrided layer was decomposed by heating during the test. (3) Nitrided specimens showed a decrease of heat resistance. The oxidation of a nitrided layer begins at 723 K (450°C) which was examined by weight, X-ray diffraction analysis and microphotographic observations.
lhara, L; Koguchi, H.; Aizawa, T.; Kihara, J.; Iwazumi, N. Determination of thicknesses of multilayered coatings by surface acoustic wave - - 2nd report, an experimental verification In a previous paper of this series, we have proposed an inversion technique for estimating the thicknesses of a multilayered coating material. The inversion is based on the measurement and analysis of the dispersion curve of the surface wave velocity. In this paper an experiment is performed to confirm the validity of the inversion technique. A two-layered coating specimen (Al/Cr/glass) was made by depositing Cr and AI films onto a glass substrate using the D.C. magnetron sputtering technique. The dispersion curve is obtained by measuring the reflection coefficients of A1/Cr/glass using an ultrasonic spectrometer. The inversions are then applied to the identification of each layer thickness. The determined thicknesses agree well with results obtained by a stylus profiling technique. Thus, it is verified that the present inversion provides an effective means of accurately determining the thicknesses of a multilayered coating material.
=
Journal o f J S N D I , Vol. 46, No. 3 p. 206
Inoue, H.; Kishimoto, K.; Nakanishi, T.; Hori, J.; Arai, M.; Shibuya, T. Determination of ultrasonic velocity and attenuation by wavelet analysis of echo waveform
Journal o f J S N D I , Vol. 46, No. 4 p. 296
Wavelet transform was applied for time-frequency analysis of waveforms obtained by an ultrasonic pulse-echo technique. The timefrequency analysis provides time variation of each frequency component involved in a waveform, which makes it possible to evaluate the ultrasonic velocity and attenuation at each frequency. In this paper, the practical accuracy of this method was examined through evaluation of ultrasonic velocity and attenuation of PMMA. In addition, the method was applied to ultrasonic evaluation of creepfatigue damage in SUS316 stainless steel.
Kato, K.; Ooka, N. Study on image quality of radiograph in radiographic examination for circumferential welded joint (Report 1) - basic study on scattered radiation in double wall exposure technique Wire type Image Quality Indicators (I.Q.I.) are usually used for the evaluation of the image quality of radiographs in radiographic examinations specified in the Japanese Industrial Standard (JIS). The relationship between the sensitivity of the Image Quality Indicator and the radiographic contrast in single wall exposure technique has already been well understood. However, the relationship in double wall exposure technique is still under discussion. As a result of the fundamental experiments using flat plates, it was found in this study that the image quality of radiograph depends on the ratio of scattered X-rays generated in the focus side test plate to transmitted X-rays, and that the ratio varies in inverse proportion to the distance between the flat plates. It was also shown that the simulation method based on the Compton Effect is effective in obtaining the ratio of scattered to transmitted X-rays in the double wall exposure technique for a pipe of more than 100 mm diameter.
Journal o f J S N D I , Vol. 46, No. 3 p. 223
Ihara, I.; Koguchi, H.; Aizawa, T.; Kihara, J.; Iwazumi, N. Determination of thicknesses of multilayered coatings by surface acoustic wave - - 1st report, utilization of inversion technique An inverse technique using surface acoustic wave (SAW) spectroscopy is applied to the nondestructive estimation of each layer thickness of a multilayered coating material. The inverse problem is formulated as an optimization problem of minimizing the differences between SAW dispersion curves obtained experimentally and numerically, where the dispersion curves are determined by analyzing the ultrasonic reflectivity of the layered material measured or calculated using the assumed layer thicknesses. First, the stability and accuracy of the solution in the inverse problem are discussed. Secondly, inverse analyses using the optimization procedure with the complex method are numerically simulated for a few sample problems. As a result, it is confirmed that the present inversion technique can be a promising way for quantitative estimation of each layer thickness of a multilayered coating material.
Journal o f J S N D I , Vol. 46, No. 4 p. 293
Kato, M.; Sato, T.; Kameyama, K.; Kosugi, Y. Evaluation of stress states in metals using stochastic model for deformation A stochastic model for deformation has been proposed to evaluate stress states in metals. The dependence of ultrasonic velocity on stress in metals can be applied to stress measurements and material characterization. The ultrasonic velocity propagating in the metal is described by higher-order effective elastic/elastic-plastic coefficients. The contribution of the deformation in the metal to acoustoelasticity is
Journal o f J S N D I , Vol. 46, No. 3 p. 223
lwanami, M.; Kamada, T.; Nagataki, S. The applicability of nondestructive testing methods to the evaluation of material deterioration in concrete
406