Materials Process Technology Center

Tokyo, Japan

Materials Process Technology Center

Tokyo, Japan
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Saito N.,Mitsubishi Group | Yari T.,Mitsubishi Group | Hotate K.,University of Tokyo | Kishi M.,University of Tokyo | And 3 more authors.
Structural Health Monitoring 2013: A Roadmap to Intelligent Structures - Proceedings of the 9th International Workshop on Structural Health Monitoring, IWSHM 2013 | Year: 2013

This paper reports the current developmental status of our structural health monitoring (SHM) technology for aircraft structures. Our SHM technology is based on Brillouin optical correlation domain analysis (BOCDA), which is one of the distributed sensing technologies using optical fiber sensors. The authors have been developing, verifying and validating the BOCDA-SHM system. The airborne BOCDA-SHM device, which can monitor strain and temperature simultaneously, has already been manufactured so far, and sensor installation method adequate to aircrafts was developed. The durability to fatigue loads and environments of the device and sensors were also verified. This paper focuses two developmental tests from among developments previously mentioned. One is flight demonstration test conducted in order to verify the BOCDA-SHM system using the airborne BOCDA device and an attached optical fiber sensor. In the test, strain and temperature monitored by the system were agreed closely with those measured by strain gages and a thermocouple. The other is bearing damage detection test conducted in order to evaluate the probability of damage detection at bolted joint portion of carbon fiber reinforced plastics (CFRP). In the tests, micro-damages occurrences could be detected almost certainly by Brillouin spectrum shape changes even if damaged area did not reach the embedded optical fiber sensor.


Sekine K.,MItsubishi Electric | Takahashi I.,MItsubishi Electric | Kume M.,MItsubishi Electric | Takeya H.,MItsubishi Electric | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The objective of this work is to develop a system for monitoring the structural integrity of composite airframe structures by strain mapping over the entire lifecycle of the structure. Specifically, we use fiber Bragg grating sensors to measure strain in a pressure bulkhead made of carbon fiber reinforced plastics (CFRPs) through a sequence of lifecycle stages (molding, machining, assembly, operation and maintenance) and detect the damage, defects, and deformation that occurs at each stage from the obtained strain distributions. In previous work, we have evaluated strain monitoring at each step in the FRP molding and machining stages of the lifecycle. In the work reported here, we evaluate the monitoring of the changes in strain that occur at the time of bolt fastening during assembly. The results show that the FBG sensors can detect the changes in strain that occur when a load is applied to the structure during correction of thermal deformation or when there is an offset in the hole position when structures are bolted together. We also conducted experiments to evaluate the detection of damage and deformation modes that occur in the pressure bulkhead during operation. Those results show that the FBG sensors detect the characteristic changes in strain for each mode. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).


Takahashi I.,MItsubishi Electric | Sekine K.,MItsubishi Electric | Kume M.,MItsubishi Electric | Takeya H.,MItsubishi Electric | And 4 more authors.
International SAMPE Technical Conference | Year: 2011

We propose structural health monitoring (SHM) technology based on the strain mapping of composite airframe structures through their life cycles including the stages of molding, machining, assembling, operation and maintenance. Our SHM system detects damages and deformation harmful to the structures by strain mapping using fiber Bragg grating (FBG) sensors. FBG sensors are suitable for life-cycle strain monitoring because reflection spectra of FBG sensors correspond to the strain applied to FBGs, which enables us to measure the strain change since the sensors were installed in structures. In this report, we conducted strain monitoring test of skin-stringer panel specimens with debondings which had different sizes and were inserted in different locations of specimens. It was confirmed that strain distribution varied with debonding size and inserted locations. In addition, we conducted strain monitoring test of open-hole CFRP panel under cyclic loading. We observed damages around the open holes of the specimen with pulse thermography. As a result, strain changed according to the initiation and propagation of delaminations. These two results demonstrate that FBG sensors can detect stringer debondings and delaminations at bolt holes which arise in composite airframe structures due to operational load in flight.


Takahashi I.,MItsubishi Electric | Sekine K.,MItsubishi Electric | Kume M.,MItsubishi Electric | Takeya H.,MItsubishi Electric | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

This paper proposes structural health monitoring technology based on the strain mapping of composite airframe structures through their life cycles by FBG sensors. We carried out operational load tests of small-sized mockup specimens of CFRP pressure bulkhead and measured the strain by FBG sensors. In addition, we confirmed strain change due to stiffener debondings. Moreover, debonding detectability of FBG sensors were investigated through the strain monitoring test of CFRP skin-stiffener panel specimens. As a result, the strain distribution varied with damage configurations. Moreover, the change in strain distribution measured by FBG sensors agrees well with numerical simulation. These results demonstrate that FBG sensors can detect stiffener debondings with the dimension of 5mm in composite airframe structures. © 2012 SPIE.


Takahashi I.,MItsubishi Electric | Sekine K.,MItsubishi Electric | Takeya H.,MItsubishi Electric | Iwahori Y.,Japan Aerospace Exploration Agency | And 3 more authors.
International SAMPE Technical Conference | Year: 2010

The purpose of this research is to develop structural health monitoring technology based on the strain mapping of composite airframe structures through their life cycles. We conducted the evaluation tests for damage detection in CFRP pressure bulkheads using FBG sensors and verified the damage detection ability and accuracy of FBG sensors on various modes of damages and deformation. As a result, damages and deformation can be detected as the changes in strain distribution measured by FBG sensors. Moreover, these changes agree well with numerical simulation. These results demonstrate that the strain mapping by FBG sensors can be used for damage detection of the CFRP pressure bulkhead.


Konno T.,Kobe Steel | Itsumi Y.,Kobe Steel | Tada K.,Kobe Steel | Kudo T.,Kobe Steel | And 2 more authors.
Ti 2011 - Proceedings of the 12th World Conference on Titanium | Year: 2012

Ti-4. 5 A1-2M6-1. 6 V-0. 5Fe-0. 3Si-0. 03 C ( KS Ti-9, registered as ASTM Gr. 35) has been developed as a coil able high strength α-β type titanium alloy and as substitute for Ti-6A1-4V in sheet product. However, α-β type alloys show strong in-plane anisotropics when manufactured by a unidirec-tional rolling process. In order to reduce in-plane anisotropics of KS Ti-9 coil sheet produced by a uni-directional rolling process, we have adopted the β rolling process,defined as the process of rolling after heating a slab over β transus. This new process results in forming a weaker transverse-texture than that obtained by the conventional process, α+β rolling process, and decreasing in-plane anisotropics. Trial sheet manufactured by the new process on a mass production line also exhibits less in-plane anisotropics and has the same properties as Ti-6Al-4 V (AMS 4911L).


Hakamada M.,Japan National Institute of Advanced Industrial Science and Technology | Watazu A.,Japan National Institute of Advanced Industrial Science and Technology | Saito N.,Japan National Institute of Advanced Industrial Science and Technology | Iwasaki H.,Materials Process Technology Center
Materials Science and Engineering A | Year: 2010

As-cast and homogenized Mg-9Al-1Zn-1Ca (in mass%) alloys were hot-compressed. Dynamic recrystallization (DRX) occurred locally around the insoluble second-phase particles during hot compression of the as-cast sample. Solute Al segregated around the particles activated basal slip operation through the c/. a ratio increase in hcp lattice, which led to the DRX localization. © 2010 Elsevier B.V.


Hakamada M.,Japan National Institute of Advanced Industrial Science and Technology | Shimizu K.,Sankyo Material Co. | Yamashita T.,Sankyo Material Co. | Watazu A.,Japan National Institute of Advanced Industrial Science and Technology | And 2 more authors.
Journal of Materials Science | Year: 2010

Two cast noncombustible Mg-9Al-1Zn-1Ca alloys (composition in mass%) with coarse and fine initial microstructures were hot forged by compression at temperatures of 523-603 K and a true strain rate of 1-10-2 s -1. The compressive stress-strain curves for the two alloys were similar and typical of metals undergoing dynamic recrystallization (DRX). The alloy with the coarse initial microstructure suffered from edge crack formation during hot forging, while the alloy with the fine initial microstructure exhibited smooth peripheral surfaces after hot forging at temperatures of 573 K and above. The reduction of grain size by DRX was similar in the two hot-forged alloys, but the recrystallized volume fraction was lower in the alloy with the coarse initial microstructure. Insoluble second phases (seemingly Al 2Ca) provide additional DRX sites, and thus it is expected that the finer initial cast microstructure will improve the microstructure in the resulting hot-forged Mg parts. © 2009 Springer Science+Business Media, LLC.

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