Prof. Yoji Okabe Profile

Prof. Yoji Okabe

Associate Professor at Univ of Tokyo

SPIE Involvement:

Author

Publications (25)

Proceedings Article | 1 July 2015 Paper

Fiber-optic ultrasonic sensing systems using PS-FBG for damage monitoring in composite materials

Yoji Okabe, Qi Wu

Proceedings Volume 9655, 96553T (2015) https://doi.org/10.1117/12.2184405

KEYWORDS: Sensing systems, Ultrasonics, Sensors, Fiber lasers, Signal detection, Ferroelectric materials, Composites, Structural health monitoring, Fiber Bragg gratings, Fiber optics sensors

Read Abstract +

Proceedings Article | 8 March 2014 Paper

Novel optical fiber ultrasonic sensor based on fiber laser

Qi Wu, Yoji Okabe, Junqiang Sun

Proceedings Volume 9062, 906209 (2014) https://doi.org/10.1117/12.2044553

KEYWORDS: Ultrasonics, Signal detection, Sensors, Fiber lasers, Ferroelectric materials, Laser systems engineering, Sensing systems, Structural health monitoring, Fiber Bragg gratings, Temperature metrology

Read Abstract +

Proceedings Article | 17 October 2012 Paper

Novel acoustic emission sensor system based on two cascaded phase-shifted fiber Bragg gratings

Qi Wu, Yoji Okabe

Proceedings Volume 8421, 84214H (2012) https://doi.org/10.1117/12.974465

KEYWORDS: Sensors, Fiber Bragg gratings, Signal detection, Ferroelectric materials, Ultrasonics, Acoustic emission, Superluminescent sources, Aluminum, Phase shifts, Electromagnetic interference

Read Abstract +

Proceedings Article | 7 April 2009 Paper

Shape-variable sandwich structure with SMA honeycomb core and CFRP skins

Yoji Okabe, Hiroshi Sugiyama

Proceedings Volume 7288, 728817 (2009) https://doi.org/10.1117/12.814014

KEYWORDS: Shape memory alloys, Skin, Beam shaping, Finite element methods, Astatine, Numerical simulations, Manufacturing, Adhesives, Temperature metrology, 3D modeling

Read Abstract +

Proceedings Article | 8 April 2008 Paper

Demonstration of detectability of SHM system with FBG/PZT hybrid system in composite wing box structure

Hideki Soejima, Toshimichi Ogisu, Hiroshi Yoneda, Yoji Okabe, Nobuo Takeda, Yasuhiro Koshioka

Proceedings Volume 6932, 69322E (2008) https://doi.org/10.1117/12.776078

KEYWORDS: Sensors, Fiber Bragg gratings, Ferroelectric materials, Structural health monitoring, Composites, Connectors, Aircraft structures, Inspection, Actuators, Skin

Read Abstract +

Proceedings Article | 11 April 2007 Paper

Impact monitoring of the aircraft composite structure using FBG sensor/PZT actuator hybrid sensor system

Noritsugu Nakamura, Toshimichi Ogisu, Hiroshi Yoneda, Yoji Okabe, Nobuo Takeda, Tateo Sakurai

Proceedings Volume 6527, 65270B (2007) https://doi.org/10.1117/12.715584

KEYWORDS: Fiber Bragg gratings, Sensors, Composites, Actuators, Aircraft structures, Ferroelectric materials, Structural health monitoring, Optical filters, Optical fibers, Reflection

Read Abstract +

Proceedings Article | 5 April 2006 Paper

Design and testing of integrated Bragg grating sensor systems for advanced grid structure

Masataro Amano, Tadahito Mizutani, Yoji Okabe, Nobuo Takeda, Tsuyoshi Ozaki

Proceedings Volume 6173, 61731C (2006) https://doi.org/10.1117/12.658127

KEYWORDS: Silver, Fiber Bragg gratings, Structural health monitoring, Sensors, Statistical analysis, 3D modeling, Finite element methods, Damage detection, Multiplexing, Signal detection

Read Abstract +

Proceedings Article | 30 March 2006 Paper

Damage growth monitoring for a bonding layer of the aircraft bonding structure

Toshimichi Ogisu, Masakazu Shimanuki, Hiroshi Yoneda, Yoji Okabe, Junichiro Kuwahara, Nobuo Takeda, Tateo Sakurai

Proceedings Volume 6171, 61710C (2006) https://doi.org/10.1117/12.658555

KEYWORDS: Fiber Bragg gratings, Sensors, Composites, Ferroelectric materials, Optical fibers, Fiber optics sensors, Structural health monitoring, Interfaces, Wave propagation, Optical components

Read Abstract +

Proceedings Article | 16 March 2006 Paper

Evaluation of debonding progress in composite bonded structures by ultrasonic wave sensing with fiber Bragg grating sensors

Yoji Okabe, Junichiro Kuwahara, Nobuo Takeda, Toshimichi Ogisu, Seiji Kojima, Shinji Komatsuzaki

Proceedings Volume 6179, 61790G (2006) https://doi.org/10.1117/12.657510

KEYWORDS: Fiber Bragg gratings, Sensors, Ultrasonics, Adhesives, Wave propagation, Wavelet transforms, Skin, Actuators, Wavelets, Optical filters

Read Abstract +

Proceedings Article | 17 May 2005 Paper

Identification of damage location in advanced grid structures using fiber Bragg grating sensor

Masataro Amano, Ichiya Takahashi, Yoji Okabe, Nobuo Takeda, Hajime Takeya, Tsuyoshi Ozaki

Proceedings Volume 5765, (2005) https://doi.org/10.1117/12.599227

KEYWORDS: Fiber Bragg gratings, Sensors, Silver, Electronic support measures, Skin, Scanning electron microscopy, Finite element methods, Composites, Analytical research, Matrices

Read Abstract +

Proceedings Article | 16 May 2005 Paper

Lamb wave sensing using fiber Bragg grating sensors for delamination detection in composite laminates

N. Takeda, Y. Okabe, J. Kuwahara, S. Kojima

Proceedings Volume 5758, (2005) https://doi.org/10.1117/12.598594

KEYWORDS: Fiber Bragg gratings, Sensors, Ultrasonics, Wave propagation, Actuators, Wave sensors, Wave plates, Optical filters, Composites, Damage detection

Read Abstract +

Proceedings Article | 16 May 2005 Paper

Damage growth detection of composite laminate using embedded FBG sensor/PZT actuator hybrid system

Toshimichi Ogisu, Masakazu Shimanuki, Satoshi Kiyoshima, Yoji Okabe, Nobuo Takeda

Proceedings Volume 5758, (2005) https://doi.org/10.1117/12.598085

KEYWORDS: Fiber Bragg gratings, Sensors, Composites, Actuators, Fiber optics sensors, Ferroelectric materials, Structural health monitoring, Aircraft structures, Interfaces, Optical fibers

Read Abstract +

This paper presents a part of the study conducted for developing a damage diagnostic system for an advanced composite material that can be utilized in next-generation aircraft structure. The authors have been working on a detection of elastic wave which can be launched from the PZT actuators, using small- and normal-diameter FBG optical fiber sensors that are bonded to the surface of the CFRP laminate under different conditions. Based on the results, it was verified that it is possible to achieve a high-accuracy detection of elastic wave by using FBG sensors bonded to the surface of the CFRP laminate. It was also verified that the damages generated on the inside of the composite material may be detected by the waveform analysis of the received elastic wave. In this study, the authors succeeded in the embedment of small-diameter FBG optical fiber sensors into the bonding surface of the double-lap type coupon specimen, which simulates the bonding structure of the CFRP composite structure. In this study, we also clarified several issues pertaining to the conditions, methods, and techniques involved in fiber embedding. An optical loss was observed during the embedment process, which may result in the loss of both accuracy and reliability. Based on these observations, the authors developed embedding techniques for optical fiber sensors that can reduce this optical loss. Additionally, the possibility of detecting an elastic wave, which was launched from the PZT actuators bonded to the surface of the coupon and directed to the host material, was verified using double-lap type coupon specimen having embedded small-diameter FBG optical fiber sensors at the bonding surface. Therefore, this specimen has provided an artificial defect that simulates the delamination generated at the bonding interface. Based on the measurements of the elastic wave, it was verified that the change in the elastic wave depends on the damage length, which is caused by the artificial defect. Moreover, based on the analysis of the received elastic wave, the possibility of damage detection was confirmed. The successful development of this damage monitoring system would ease the implementation of structural health monitoring system in aircraft structures in the near future.

Proceedings Article | 16 May 2005 Paper

Identification of impact damage in sandwich structures by application of high speed MEMS-OSA to FBG sensors

Y. Okabe, S. Minakuchi, N. Takeda

Proceedings Volume 5758, (2005) https://doi.org/10.1117/12.598333

KEYWORDS: Fiber Bragg gratings, Sensors, Reflection, Optical fibers, Adhesives, Mirrors, Aluminum, Skin, Spectrum analysis, Fiber optics sensors

Read Abstract +

Proceedings Article | 29 July 2004 Paper

Development of damage monitoring system for aircraft structure using a PZT actuator/FBG sensor hybrid system

Toshimichi Ogisu, Masakazu Shimanuki, Satoshi Kiyoshima, Yoji Okabe, Nobuo Takeda

Proceedings Volume 5388, (2004) https://doi.org/10.1117/12.539727

KEYWORDS: Sensors, Fiber Bragg gratings, Composites, Ferroelectric materials, Aircraft structures, Actuators, Fiber optics sensors, Electronic filtering, Aluminum, Reliability

Read Abstract +

This paper presents a part of the research results on a damage monitoring system using PZT actuators/FBG sensors for advanced composite material structures of new-generation aircrafts. To achieve weight reduction of the aircraft structure, these advanced composite materials have gradually been employed for the primary structure. It is expected that when these materials are extensively employed, an efficient bonded structure such as a hat-shaped stringer will be utilized for the aircraft structure. However, these bonded structures have critical problems such as debonding and delamination at the interfaces of the laminate. Further, a single-step molding process of the structure elements is necessary in order to ensure low cost and thus affordability. However, this low-cost process results in an increase in the non-destructive inspection (NDI) cost. Therefore, an innovative damage monitoring system is required for structural health management. In the present study, the authors have developed a hybrid sensor system that can detect the elastic waves launched from the piezo transducer (PZT) actuator using a high-speed and high-accuracy fiber Bragg grating (FBG) sensor to resolve the issues mentioned above. In this study, the conceptual design of an aircraft that can employ this damage monitoring system was carried out. Subsequently, the application area was selected based on cases of certain kinds of damage. Further, the validity of the damage monitoring system for the verification of the structural integrity of the aircraft was discussed. Next, in order to verify the elastic wave detectability of the FBG sensor, it was confirmed that an elastic wave of 300 kHz is detectable at a distance of 5 cm between the PZT actuator and FBG sensor using an aluminum sheet and CFRP cross-ply laminate and also by considering the relationship between sensor length and sensitivity. Through the present research results, the possibility of applying the damage monitoring system to the composite material bonding structure in an aircraft is presented.

Proceedings Article | 26 July 2004 Paper

Debonding monitoring of a composite repair patch using small-diameter FBG sensors

Shin-ichi Takeda, Takeharu Yamamoto, Yoji Okabe, Nobuo Takeda

Proceedings Volume 5390, (2004) https://doi.org/10.1117/12.539722

KEYWORDS: Fiber Bragg gratings, Sensors, Adhesives, Aluminum, Composites, Reflection, Thermography, Carbon, Structured optical fibers, Photography

Read Abstract +

Proceedings Article | 5 August 2003 Paper

Application of fiber Bragg grating sensors to real-time strain measurement of cryogenic tanks

Nobuo Takeda, Tadahito Mizutani, Kentaro Hayashi, Yoji Okabe

Proceedings Volume 5056, (2003) https://doi.org/10.1117/12.483406

KEYWORDS: Sensors, Fiber Bragg gratings, Cryogenics, Composites, Adhesives, Liquids, Temperature metrology, Polyurethane, Reflection, Optical fibers

Read Abstract +

Proceedings Article | 22 July 2003 Paper

Application of chirped FBG sensors for detection of local delamination in composite laminates

Shin-ichi Takeda, Yoji Okabe, Nobuo Takeda

Proceedings Volume 5050, (2003) https://doi.org/10.1117/12.484243

KEYWORDS: Fiber Bragg gratings, Sensors, Composites, Refractive index, Optical fibers, Carbon, Spectrum analysis, Smart materials, Wave propagation, Cladding

Read Abstract +

Proceedings Article | 27 June 2002 Paper

Crack identification in CFRP laminates using small-diameter FBG sensors

Tadahito Mizutani, Yoji Okabe, Nobuo Takeda

Proceedings Volume 4694, (2002) https://doi.org/10.1117/12.472638

KEYWORDS: Fiber Bragg gratings, Sensors, Optical fibers, Reflectivity, Refractive index, Inverse scattering, Finite element methods, Cladding, Carbon, Reflection

Read Abstract +

Proceedings Article | 27 June 2002 Paper

Detection of delamination in composite laminates using small-diameter FBG sensors

Shin-ichi Takeda, Yoji Okabe, Nobuo Takeda

Proceedings Volume 4694, (2002) https://doi.org/10.1117/12.472611

KEYWORDS: Fiber Bragg gratings, Sensors, Composites, Optical fibers, Edge detection, Reflection, Interfaces, Refractive index, Carbon, X-rays

Read Abstract +

Proceedings Article | 27 June 2002 Paper

Application of chirped fiber Bragg grating sensors for damage identification in composites

Nobuo Takeda, Yoji Okabe, Ryohei Tsuji, Shin-ichi Takeda

Proceedings Volume 4694, (2002) https://doi.org/10.1117/12.472608

KEYWORDS: Fiber Bragg gratings, Sensors, Reflection, Composites, Optical fibers, Refractive index, Wave propagation, Carbon, Coating, Computer simulations

Read Abstract +

Proceedings Article | 27 June 2002 Paper

Temperature-compensated strain measurement using FBG sensors embedded in composite laminates

Nobuhira Tanaka, Yoji Okabe, Nobuo Takeda

Proceedings Volume 4694, (2002) https://doi.org/10.1117/12.472634

KEYWORDS: Sensors, Fiber Bragg gratings, Temperature metrology, Epoxies, Optical fibers, Composites, Birefringence, Adhesives, Carbon, Glasses

Read Abstract +

Proceedings Article | 18 June 2002 Paper

Effect of thermal residual stress on the reflection spectrum from FBG sensors embedded in CFRP composites

Yoji Okabe, Shigeki Yashiro, Ryohei Tsuji, Tadahito Mizutani, Nobuo Takeda

Proceedings Volume 4704, (2002) https://doi.org/10.1117/12.470709

KEYWORDS: Fiber Bragg gratings, Sensors, Thermal effects, Reflection, Temperature metrology, Optical fibers, Birefringence, Coating, Manufacturing, Composites

Read Abstract +

Proceedings Article | 6 August 2001 Paper

Application of small-diameter FBG sensors for detection of damages in composites

Yoji Okabe, Tadahito Mizutani, Shigeki Yashiro, Nobuo Takeda

Proceedings Volume 4328, (2001) https://doi.org/10.1117/12.435532

KEYWORDS: Sensors, Fiber Bragg gratings, Optical fibers, Composites, Reflection, Coating, Carbon, Cladding, Refractive index, Smart materials

Read Abstract +

Proceedings Article | 12 June 2000 Paper

Real-time detection of impact load on composite laminates with embedded small-diameter optical fiber

Hiroaki Tsutsui, Tomio Sanda, Yoji Okabe, Nobuo Takeda

Proceedings Volume 3986, (2000) https://doi.org/10.1117/12.388098

KEYWORDS: Optical fibers, Composites, Cladding, Sensors, Coating, Single mode fibers, Fiber optics sensors, Carbon, Smart materials, Multimode fibers

Read Abstract +

Proceedings Article | 12 June 2000 Paper

Detection of transverse cracks in composites by using embedded FBG sensors

Yoji Okabe, Shigeki Yashiro, Tatsuro Kosaka, Nobuo Takeda

Proceedings Volume 3986, (2000) https://doi.org/10.1117/12.388116

KEYWORDS: Sensors, Fiber Bragg gratings, Optical fibers, Composites, Reflection, Refractive index, Manufacturing, Finite element methods, Carbon, Smart materials

Read Abstract +

Showing 5 of 25 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years