成果報告書詳細
管理番号20140000000118
タイトル*平成25年度中間年報 水素利用技術研究開発事業 燃料電池自動車及び水素供給インフラの国内規制適正化、国際基準調和・国際標準化に関する研究開発 水素ステーション用複合容器の供用中検査手法の研究開発
公開日2015/9/1
報告書年度2013 - 2013
委託先名千代田化工建設株式会社
プロジェクト番号P13002
部署名新エネルギー部
和文要約
英文要約1.1 Introduction
The aim of study at 1st stage is to get a database regarding acoustic emission (AE) measurement in order to evaluate the fatigue damage which is occurred in aluminum liner used for TypeIII-CFRP Pressure vessel of Hydrogen Station.
The AE measurement was applied to the following items:
・Plate specimen
・Hour-glass specimen
・Aluminum liner
・TypeIII-CFRP Pressure vessel

1.2 Study of acoustic emission by using aluminum alloy fatigue test specimen
In connection with fatigue of Aluminum alloy which is used TypeIII-CFRP Pressure vessel, the bending fatigue test with AE measurement has been executed to get some data of AE characteristics which are occurred by the fatigue.
It is confirmed that a test specimen with mirror surface had a longer life against ones without surface treatment. We considered a concentration of stress at small scratch of material was triggered a fracture of the specimen. The mirror surface treatment improves a fracture life of TypeIII-CFRP Pressure vessel.
In the case of 288MPa and 240MPa as maximum bending stress, Some AE of the high amplitude is observed at early time. In the case of 336MPa, AE of the high amplitude is observed from 70% of the fatigue life. To confirm a behavior of the fatigue, the special filter which is used for condition monitoring of bearing by Chiyoda is applied to the AE data of 240MPa. As a result, the time characteristics by the AE parameter indicated as a step-by-step increase with fatigue life of the material.
AE measurement of hour-glass test specimen was executed on an experiment by JPEC. As a result of AE measurements regarding the test, it confirmed that amplitude of AE increased from 50% of remaining life of the material before the broken. AE amplitude had remarkably increased from 90% of the remaining life.
1.3 Study of acoustic emission by using aluminum alloy fatigue test specimen in water
An experiment of AE propagation with fatigue of Aluminum was immersed in water was executed in order to provide a clue for the tests of Tanks filled with water.
As a result, we have found that AE amplitude with water condition is attenuated to about 1/3 compared to the test without water.
It is seemed that the AE waves propagating through the material surface is absorbed in water phase.
Remaining life with water condition is shorter than without water because water erosion at many cracks is trigger of the fatigue.

1.4 Study of acoustic emission regarding fatigue test for TypeIII-CFRP Pressure vessel
Measurement under an experiment regarding fatigue test for TypeIII-CFRP Pressure vessel by JPEC has been executed in order to identification of acoustic emission by fatigue on the assumption that hydrogen station is operated in future.
In case of Aluminum liner, AE waves of large amplitude with sporadic were observed from 25% of fatigue fracture.
In spite of test during two months in the stress amplitude of 90MPa as TypeIII-CFRP Pressure vessel, a fracture of the tank did not occur. Data obtained thus far is continuously being analyzed.

1.5 Conclusion
It was revealed that AE can detect a minute crack generation and progress. Therefore, AE has been used for the quality control of the pressure vessel. It was expected that AE was very slight because aluminum was a ductile material. However, it has been understood to be able to detect AE by the research at current year.

There is a possibility that many fatigue cracks are occured in plurality of locations as a result of AE measurement and analysis. It was suggested that the fatigue and the remaining life of the material can be evaluated in connection with the characteristics by the AE parameter.
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