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極低温推進剤を用いるロケットにおいて、極低温推進剤タンクの複合材料化は従来の金属製推進剤タンクと比べて機体構造重量の低減に効果的であり、そのようなタンク構造では複合材料と複合材料または金属材料と複合材料の接着構造も組立構造や配管との接続のために重要になってくる。接着継手試験片の極低温力学的特性評価試験の実施を目的として、複合材料積層板の極低温二軸試験用に開発された冷凍機式極低温環境槽に適用できるダブルラップ接着継手試験片用改良型冷却方式を紹介する。複合材料積層板の冷却方式を直接ダブルラップ接着継手試験片に適用することは、接着部を十分に冷却できない問題と、接着部を上下から抑え込むことにより適切に強度試験ができないなど問題が生じる。その問題を解決するために、従来の冷却プレートに加え、追加冷却プレートとしわ加工アルミ箔を用いた改良型の冷却方式を考案した。考案した改良型冷却方式に対して、複合材-複合材接着試験片と複合材-アルミ合金接着試験片を用いて、ダブルラップ接着継手試験片の極低温負荷試験が適切に実施できること、および30K以下の冷却が可能であることを確認した。また、140K以上の試験温度にも対応できるような冷却方式も考案した。その結果、追加冷却プレートやしわ加工アルミ箔を使うことにより、約25Kから170Kの温度領域で、ダブルラップ接着継手の破壊試験が適切にできることが明らかとなった。, In the development of high-performance rockets, composite cryogenic propellant tanks have an advantage over conventional metallic propellant tanks owing to their ability to efficiently reduce structural weight. Adhesively bonded composite-metallic structures are very important for the assembly of composite cryogenic tanks with composite and metallic parts. To investigate the bonded structures at cryogenic temperature, an improved cooling method, which used a cryogenic testing system with a refrigerator developed for biaxial evaluation of composite laminates, was designed to evaluate the cryogenic mechanical properties of double-lap bonded joint specimens. However, the application of the conventional cooling method based on cooling plates for the composite laminate to the double-lap bonded joint suffers from an insufficient cooling capacity of the specimen gauge area and an inappropriate restriction of out-of-plane deformation of the specimen. To solve these problems, an improved cooling method with additional cooling plates and wrinkled aluminum foils was designed for the double-lap bonded specimens. The performance of the improved cooling method to conduct appropriate cryogenic mechanical testing and to cool the specimen gauge area to below 30 K was verified with composite-composite and composite-aluminum alloy bonded joint specimens. Additionally, another improved cooling method to expand the temperature range of the cryogenic testing system to more than 140 K was designed. The test results with these improved cooling methods indicate the capability to conduct tensile tests of double-lap bonded joint specimen at an approximate temperature range between 25 K to 170 K., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1930006000, レポート番号: JAXA-RM-19-002

Objectives/Interrogation: In osteochondritis dissecans (OCD) of the elbow, severity of the lesion affects prognosis and selection of treatment. It is difficult to precisely evaluate lesions even with magnetic resonance imaging (MRI) or computed tomography (CT). We developed a novel technique to[for full text, please go to the a.m. URL], 14th Triennial Congress of the International Federation of Societies for Surgery of the Hand (IFSSH), 11th Triennial Congress of the International Federation of Societies for Hand Therapy (IFSHT), 11th Triennial Congress of the International Federation of Societies for Hand Therapy (IFSHT)

ロケットなどの高性能化のための機体重量軽減に, 極低温液体推進剤タンクの複合材料化が効果的である. 本研究では, 炭素繊維エポキシ複合材料を材料とし, 極低温におけるCFRPクロスプライ積層板の弾性率, 破断強度, 内部損傷進展を冷凍機式極低温試験システムを用いて取得した. 極低温にて取得した試験結果は, 常温の結果と比較し, 液化推進剤がもたらす極低温が複合材料の基礎的力学特性に及ぼす影響を明らかにした. 極低温での複合材料積層板の力学的特性はその結果, 弾性率は, 極低温においてわずかに弾性率が上昇にとどまるが, 複合材料積層板の損傷発生応力と破断強度は常温に比べ極低温において顕著に低くなることが明らかとなった. また, 冷凍機式極低温試験について, ヒータを用いた温度調節手法, 極低温でのひずみ測定手法についても本報告にまとめた., Incorporation of composite materials in cryogenic propellant tanks can potentially aid in developing high performance rockets. This study thus evaluates various aspects of carbon fiber reinforced epoxy laminates, such as elastic constants, failure strength, and development of internal damages, at cryogenic temperatures by employing a cryogenic testing system comprising a cryostat and a refrigerator. Test results obtained at cryogenic temperatures were compared with those at the room temperature for studying the effect of liquefied propellant's cryogenic temperature on the fundamental mechanical properties of composite materials. The obtained results indicate that compared to the room temperature, the damage initiation stress and failure strength of the composite laminates at cryogenic temperatures can decrease significantly, whereas the stiffness of the composite laminates at cryogenic temperatures can increase marginally. Furthermore, this study report also describes a method for temperature control through a heater system, and a method for stress measurement at cryogenic temperatures using the cryogenic testing system with the help of a refrigerator., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1830009000, レポート番号: JAXA-RM-18-003