2022 Fiscal Year Research-status Report
Elucidation of dwell-fatigue behavior in Ti-6Al-4V alloys by AE monitoring and Crystal plasticity simulations
| Project/Area Number |
22K14139
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ブリフォ ファビャン 東京大学, 大学院工学系研究科(工学部), 特任助教 (70836890)
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| Project Period (FY) |
2022-04-01 – 2024-03-31
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| Keywords | DIC / Fatigue / Ti-6Al-4V / crack initiation / macrozone |
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| Outline of Annual Research Achievements |
The main objective of this research is to elucidate cold dwell fatigue mechanisms in Ti6Al-4V alloys in comparison with pure fatigue through a combination of in-situ observationsand numerical simulations. The specific progresses are described below:
(1)A High-resolution strain mapping method based on the digital image correlation of surface nano-scale pattern produced by gold nanolayered film through vapor-assisted remodeling was developed.
(2)An automated framework for identifying slip system and assessing strain localization of slip bands termed ASSISL (automated Slip System Identification and Strain Localization analysis of slip bands) was developed.
(3)The framework was applied to quantifying the differences in strain partitioning between pure and dwell fatigue.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
As originally planned, we were able to experimentally quantify strain partitioning in Ti-6Al-4V alloy under pure fatigure and dwell fatigue. The developed automated procedure allowed us to save a significant time in the large data produced by HR-DIC.
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| Strategy for Future Research Activity |
In the future, the microstructures observed experimentally by EBSD and DIC will be directly used as a numerical model using the crystal plasticity finite element method. The microstructures will be subjected to the same loading conditions as in experiments and direct comparison will be made between the experimental and numerical strain fields to clarify the predictive capabilities of the numerical method and identify fatigue criteria to predict fatigue crack initiation.
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| Causes of Carryover |
1. Because of the Covid situation, the applicant could not attend any international conference in FY2022.The applicant applied to an international conference in the US (ICF15, Atlanta) for the FY2023. The budget will partly be used to cover the travel expense.
2. The cost of specimen machining and AE system (sensor, HDD) was lower than expected. The remaining budget will be used to buy additional license tokens for the FEM simulations and use Amazon Web Service to accelerate the simulations.
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