The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Yoshinobu Shimamura - One of the best experts on this subject based on the ideXlab platform.
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measurement of orthotropic electric conductance of cfrp laminates and analysis of the effect on Delamination monitoring with an electric resistance change method
Composites Science and Technology, 2002Co-Authors: Akira Todoroki, Miho Tanaka, Yoshinobu ShimamuraAbstract:Since Delaminations of composite laminates are usually invisible or difficult to detect by visual inspections, Delamination causes low reliability for primary structures. Automatic systems for Delamination identifications in-service are desired in order to improve this low reliability. The present study employs an electric resistance change method for detection of Delaminations. Since the method adopts reinforcement carbon fibre itself as sensors for Delamination detections, this method does not cause reduction of static strength or fatigue strength; also, this method is applicable to existing structures. In the present study, a relationship between fibre volume fraction and orthotropic electric conductivities is confirmed by experimentation and the effect of measured orthotropic electric conductance on Delamination monitoring is discussed analytically with FEM analyses. Two types of cross-ply laminates are prepared for Delamination monitoring analyses: [0/90]s and [90/0]s. Electric resistance changes due to Delamination creation are discussed for both specimen types with results of electric current density diagrams. As a result, it can be concluded that the fibre volume fraction has a large effect on electric conductance of the transverse and thickness directions, and electric conductance of the thickness direction has significant effects on Delamination detection with the electric resistance change method.
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Measurement of orthotropic electric conductance of CFRP laminates and analysis of the effect on Delamination monitoring with an electric resistance change method
Composites Science and Technology, 2002Co-Authors: Akira Todoroki, Miho Tanaka, Yoshinobu ShimamuraAbstract:Since Delaminations of composite laminates are usually invisible or difficult to detect by visual inspections, Delamination causes low reliability for primary structures. Automatic systems for Delamination identifications in-service are desired in order to improve this low reliability. The present study employs an electric resistance change method for detection of Delaminations. Since the method adopts reinforcement carbon fibre itself as sensors for Delamination detections, this method does not cause reduction of static strength or fatigue strength; also, this method is applicable to existing structures. In the present study, a relationship between fibre volume fraction and orthotropic electric conductivities is confirmed by experimentation and the effect of measured orthotropic electric conductance on Delamination monitoring is discussed analytically with FEM analyses. Two types of cross-ply laminates are prepared for Delamination monitoring analyses: [0/90]s and [90/0]s. Electric resistance changes due to Delamination creation are discussed for both specimen types with results of electric current density diagrams. As a result, it can be concluded that the fibre volume fraction has a large effect on electric conductance of the transverse and thickness directions, and electric conductance of the thickness direction has significant effects on Delamination detection with the electric resistance change method. © 2002 Elsevier Science Ltd. All rights reserved.
S. Takeda - One of the best experts on this subject based on the ideXlab platform.
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Delamination monitoring of laminated composites subjected to low velocity impact using small diameter fbg sensors
Composites Part A-applied Science and Manufacturing, 2005Co-Authors: Shu Minakuchi, Yoji Okabe, S. Takeda, Nobuo TakedaAbstract:Small-diameter fiber Bragg grating (FBG) sensors were applied for the monitoring of Delamination induced by low-velocity impact. The FBG sensors were embedded into carbon fiber reinforced plastic (CFRP) laminates [04/904/04]. Using a drop-weight impact tester, an impact loading was applied to the laminates at four impact energy levels. After the impact tests, the internal damages including Delaminations were observed by ultrasonic C-scan, and the reflection spectra from the embedded FBG sensors were measured. The form of the spectrum changed sensitively depending on the Delamination size. Furthermore, the spectra were calculated theoretically for confirmation of the measured spectra. Since the change in the measured spectrum was consistent with that in the calculated spectrum, the relationship between the Delamination size and the form of the spectrum could be clarified. From the results, the present method using small-diameter FBG sensors was found to be effective for the monitoring of the Delamination.
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Delamination monitoring of laminated composites subjected to low-velocity impact using small-diameter FBG sensors
Composites Part A: Applied Science and Manufacturing, 2005Co-Authors: S. Takeda, Shu Minakuchi, Yoji Okabe, Nobuo TakedaAbstract:Small-diameter fiber Bragg grating (FBG) sensors were applied for the monitoring of Delamination induced by low-velocity impact. The FBG sensors were embedded into carbon fiber reinforced plastic (CFRP) laminates [04/904/04]. Using a drop-weight impact tester, an impact loading was applied to the laminates at four impact energy levels. After the impact tests, the internal damages including Delaminations were observed by ultrasonic C-scan, and the reflection spectra from the embedded FBG sensors were measured. The form of the spectrum changed sensitively depending on the Delamination size. Furthermore, the spectra were calculated theoretically for confirmation of the measured spectra. Since the change in the measured spectrum was consistent with that in the calculated spectrum, the relationship between the Delamination size and the form of the spectrum could be clarified. From the results, the present method using small-diameter FBG sensors was found to be effective for the monitoring of the Delamination. © 2005 Elsevier Ltd. All rights reserved.
Nobuo Takeda - One of the best experts on this subject based on the ideXlab platform.
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Delamination monitoring of laminated composites subjected to low velocity impact using small diameter fbg sensors
Composites Part A-applied Science and Manufacturing, 2005Co-Authors: Shu Minakuchi, Yoji Okabe, S. Takeda, Nobuo TakedaAbstract:Small-diameter fiber Bragg grating (FBG) sensors were applied for the monitoring of Delamination induced by low-velocity impact. The FBG sensors were embedded into carbon fiber reinforced plastic (CFRP) laminates [04/904/04]. Using a drop-weight impact tester, an impact loading was applied to the laminates at four impact energy levels. After the impact tests, the internal damages including Delaminations were observed by ultrasonic C-scan, and the reflection spectra from the embedded FBG sensors were measured. The form of the spectrum changed sensitively depending on the Delamination size. Furthermore, the spectra were calculated theoretically for confirmation of the measured spectra. Since the change in the measured spectrum was consistent with that in the calculated spectrum, the relationship between the Delamination size and the form of the spectrum could be clarified. From the results, the present method using small-diameter FBG sensors was found to be effective for the monitoring of the Delamination.
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Delamination monitoring of laminated composites subjected to low-velocity impact using small-diameter FBG sensors
Composites Part A: Applied Science and Manufacturing, 2005Co-Authors: S. Takeda, Shu Minakuchi, Yoji Okabe, Nobuo TakedaAbstract:Small-diameter fiber Bragg grating (FBG) sensors were applied for the monitoring of Delamination induced by low-velocity impact. The FBG sensors were embedded into carbon fiber reinforced plastic (CFRP) laminates [04/904/04]. Using a drop-weight impact tester, an impact loading was applied to the laminates at four impact energy levels. After the impact tests, the internal damages including Delaminations were observed by ultrasonic C-scan, and the reflection spectra from the embedded FBG sensors were measured. The form of the spectrum changed sensitively depending on the Delamination size. Furthermore, the spectra were calculated theoretically for confirmation of the measured spectra. Since the change in the measured spectrum was consistent with that in the calculated spectrum, the relationship between the Delamination size and the form of the spectrum could be clarified. From the results, the present method using small-diameter FBG sensors was found to be effective for the monitoring of the Delamination. © 2005 Elsevier Ltd. All rights reserved.
Akira Todoroki - One of the best experts on this subject based on the ideXlab platform.
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Delamination identification of cross ply graphite epoxy composite beams using electric resistance change method
Composites Science and Technology, 2002Co-Authors: Akira Todoroki, Yuuki TanakaAbstract:Detection of Delaminations is a difficult task for visual inspections. Difficulty of detection underlines the importance of development of smart structures for monitoring Delaminations of graphite/epoxy laminated composites. This study employs an electric resistance change method for identification of Delamination location and size; applicability of the method is investigated experimentally using beam-type specimens fabricated from cross-ply laminates. On the specimen surface, multiple electrodes are mounted by co-curing copper foil to measure electric resistance changes. Interlamina shear tests are conducted to create a practical Delamination crack in a beam-type specimen. Five beam specimen types were made and tested. A large number of tests were conducted to obtain a data set for solving inverse problems to estimate Delamination location and size from measured electric resistance changes. Response surfaces are employed for a solver of inverse problems instead of well-known artificial neural networks. As a result, the method successfully identifies Delamination location and size for these beam type specimens. To obtain practically efficient estimation performance, at least five electrodes are indispensable for these beam type specimens.
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measurement of orthotropic electric conductance of cfrp laminates and analysis of the effect on Delamination monitoring with an electric resistance change method
Composites Science and Technology, 2002Co-Authors: Akira Todoroki, Miho Tanaka, Yoshinobu ShimamuraAbstract:Since Delaminations of composite laminates are usually invisible or difficult to detect by visual inspections, Delamination causes low reliability for primary structures. Automatic systems for Delamination identifications in-service are desired in order to improve this low reliability. The present study employs an electric resistance change method for detection of Delaminations. Since the method adopts reinforcement carbon fibre itself as sensors for Delamination detections, this method does not cause reduction of static strength or fatigue strength; also, this method is applicable to existing structures. In the present study, a relationship between fibre volume fraction and orthotropic electric conductivities is confirmed by experimentation and the effect of measured orthotropic electric conductance on Delamination monitoring is discussed analytically with FEM analyses. Two types of cross-ply laminates are prepared for Delamination monitoring analyses: [0/90]s and [90/0]s. Electric resistance changes due to Delamination creation are discussed for both specimen types with results of electric current density diagrams. As a result, it can be concluded that the fibre volume fraction has a large effect on electric conductance of the transverse and thickness directions, and electric conductance of the thickness direction has significant effects on Delamination detection with the electric resistance change method.
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Measurement of orthotropic electric conductance of CFRP laminates and analysis of the effect on Delamination monitoring with an electric resistance change method
Composites Science and Technology, 2002Co-Authors: Akira Todoroki, Miho Tanaka, Yoshinobu ShimamuraAbstract:Since Delaminations of composite laminates are usually invisible or difficult to detect by visual inspections, Delamination causes low reliability for primary structures. Automatic systems for Delamination identifications in-service are desired in order to improve this low reliability. The present study employs an electric resistance change method for detection of Delaminations. Since the method adopts reinforcement carbon fibre itself as sensors for Delamination detections, this method does not cause reduction of static strength or fatigue strength; also, this method is applicable to existing structures. In the present study, a relationship between fibre volume fraction and orthotropic electric conductivities is confirmed by experimentation and the effect of measured orthotropic electric conductance on Delamination monitoring is discussed analytically with FEM analyses. Two types of cross-ply laminates are prepared for Delamination monitoring analyses: [0/90]s and [90/0]s. Electric resistance changes due to Delamination creation are discussed for both specimen types with results of electric current density diagrams. As a result, it can be concluded that the fibre volume fraction has a large effect on electric conductance of the transverse and thickness directions, and electric conductance of the thickness direction has significant effects on Delamination detection with the electric resistance change method. © 2002 Elsevier Science Ltd. All rights reserved.
Toshiyuki Hashida - One of the best experts on this subject based on the ideXlab platform.
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Thermal fatigue failure induced by Delamination in thermal barrier coating
International Journal of Fatigue, 2002Co-Authors: Y. C. Zhou, Toshiyuki HashidaAbstract:The paper presents the experimental and theoretical investigation on the thermal fatigue failure induced by Delamination in thermal barrier coating system. Laser heating method was used to simulate the operating state of TBC (thermal barrier coating) system. The non-destructive evaluation such as acoustic emission (AE) detect was used to study the evolution of TBC system damage. Micro-observation and AE detect both revealed that fatigue crack was in two forms: surface crack and interface Delamination. It was found that interface Delamination took place in the period of cooling or heating. Heating or cooling rate and temperature gradient had an important effect on interface Delamination cracking propagation. A theoretical model on interface Delamination cracking in TBC system at operating state is proposed. In the model, a membrane stress P and a bending moment M are designated the thermal loads of the thermal stress and temperature gradient in TBC system. In this case, the coupled effect of plastic deformation, creep of ceramic coating as well as thermal growth oxidation (TGO) and temperature gradient in TBC system was considered in the model. The thermal stress intensity factors (TSIFs) in non-FGM (functional gradient material) thermal barrier coating system is analytical obtained. The numerical results of TSIFs reveal some same results as obtained in experimental test. The model is based on fracture mechanics theory about heterogeneous materials and it gives a rigorous explanation of Delaminations in TBC system loaded by thermal fatigue. Both theoretical analysis and experimental observation reveal an important fact: Delaminations are fatigue cracks which grow during thermal shocks due to compressive stresses in the loading, this loads the Delaminations cracks in mixed I and II mode. © 2002 Elsevier Science Ltd. All rights reserved.
