Investigation of the dominant mechanics of fatigue crack propagation in freestanding metallic nano-films considering cyclic plasticity

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H06061
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Materials/Mechanics of materials
• Research Institution: Osaka University
• Principal Investigator: Kondo Toshiyuki 大阪大学, 工学研究科, 助教 (70735042)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 材料強度学 / ナノ材料 / 薄膜 / 疲労 / 破壊 / 塑性/繰返し塑性

Outline of Final Research Achievements

To investigate the dominant mechanics of fatigue crack propagation in submicrometer-thick freestanding metallic nano-films, a tensile/cyclic tensile testing system for small nano-film specimen and a method for evaluating cyclic deformation field around a fatigue crack on the basis of in situ field emission scanning electron microscope observations were developed. The quantitative evaluations of the elasto-plastic properties of the nano-films in a large stress-strain range and the strain field around a fatigue crack were achieved in submicrometer-thick copper films. These methods are able to clarify the dominant mechanics of fatigue crack propagation.

Free Research Field

機械工学，機械材料・材料力学

Academic Significance and Societal Importance of the Research Achievements

マイクロ・ナノ材料の変形・破壊の支配力学は未解明であり，これはき裂先端などの破壊進行領域近傍の力学状態の詳細な解明が困難なことに因る。本研究で得た知見や確立した技術は，マイクロ・ナノ材料の機械的特性の高精度な評価や破壊箇所近傍の力学状態の解明を実現し，マイクロ・ナノ材料における破壊の支配力学を解明するための基盤となるものである。特に，マイクロ・ナノデバイスの長期信頼性を確保するうえで重要である疲労破壊の解明に大きく貢献するものであり，学術的・社会的意義が大きいものである。