2021 Fiscal Year Annual Research Report
Understanding strengthening in mille-feuille structures via mesoscale modeling of structural and material instabilities
Publicly Offered Research
| Project Area | Materials science on mille-feullie structure -Developement of next-generation structural materials guided by a new strengthen principle- |
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| Project/Area Number |
21H00102
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| Research Institution | Kyushu University |
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Principal Investigator |
Cesana Pierluigi 九州大学, マス・フォア・インダストリ研究所, 准教授 (60771532)
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | Disclinations / Kink formation / Calculus of Variations / Solid Mechanics |
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| Outline of Annual Research Achievements |
My work during FY21 has been, on one side, on the development of computer codes for numerical solutions of boundary value problems for mechanical models of elastic crystals and on the other hand on the analysis of variational models in elasto-plasticity.
Developed a numerical program based on Finite Elements and performed numerical calculations for traction/compression tests of columnar structures of metal alloys. Discovered the dependence of kink morphologies (ortho-kinks, kink bands and ridge kinks) emerging from the interplay of elastic vs. material instabilities on lattice symmetry (hexagonal vs. square) and domain aspect ratio. (1 paper in preparation).
Accomplished the meso-scale modeling, via variational principle, of systems of interacting disclinations-dislocations which are proxies for kinks. Constructed a comprehensive variational theory for the Airy stress function method. Computed effective energies with Gamma-convergence (1 paper in preparation).
Developed a platform of numerical programs and models for supervised learning with the goal of accelerating and automatizing the design of functional structures and metal alloys (1 paper published).
Modeled and analyzed evolution of avalanches on lattices as General Branching Random Walks (1 paper accepted for publication).
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The project is progressing very well and crucial results are expected to be obtained during FY22. A paper on the mesoscale modeling of systems of disclinations and dislocations will be submitted for publication soon in FY22. This paper sets a general theory to treat interacting wedge disclinations and edge dislocations via energy minimization. This research paves the way to more specific analysis such as homogenization of multi-layer structures (as in LPSO materials), constructions of stress-strain curves for metals with plastification at various length-scales, numerical computations for traction/compression tests.
A paper on the modeling and analysis of lattice avalanches has been accepted for publication on "The Journal of Applied Probability" in December 2021. A paper on applications of Machine Learning techniques in materials chemistry has been accepted for publication in January 2022 on "Machine Learning with Applications".
A paper describing numerical computations of kink formation in columnar structures based on a continuum model capable of describing micro-plasticity is currently in progress.
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| Strategy for Future Research Activity |
I will compute solutions to compression and extension experiments for metal alloys in simple domains with the micro-plasticity model developed in FY21. I will compute stress-strain curves and show the effect of material/geometry parameters on kink morphologies.
I will carry on variational analysis of meso-scale models with a semi-discrete (diffuse-core) approach by means of Gamma-convergence for systems of interacting disclinations and dislocations. I will construct kinks as solutions to boundary value problems. I will study homogenization of multi-layer structures for elasto-plastic models of elastic crystals in 2D geometries.
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