Nano-scale analysis and micro-scale formulation on crystal grain dynamics

• Project/Area Number: 17K06042
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: Yamagata University
• Principal Investigator: Uehara Takuya 山形大学, 大学院理工学研究科, 教授 (50311741)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2017: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: 分子動力学 / 結晶粒界 / 塑性変形 / 変形挙動 / 機械材料・材料力学 / 計算機シミュレーション / マルチスケール / 分子動力学法 / フェーズフィールドモデル

Outline of Final Research Achievements

The construction of a multi-scale analysis on the dynamic behavior of grain boundaries, which are expected to fill the gap between nano- and micro-scales, are targeted. On the nano-scale, a polycrystalline model consisting of four grains were constructed, and tensile or compressive simulations were carried out. The motion of atoms at grain boundaries upon yielding were observed in detail. As a result, an initiation of plastic deformation and the expansion occurred, and it revealed that the yielding and plastic deformation behaviors depend on the orientation and geometric characteristics of the grain boundaries. Also, a combined model of particle and phase-field models was proposed, leading to the complete construction of a multi-scale grain-boundary model.

Academic Significance and Societal Importance of the Research Achievements

ナノスケールとマイクロスケールをつなぐマルチスケールモデルについては，依然として確立されたモデルは見られないが，本研究では，簡単な分子動力学モデルを作成して解析することによって，様々な降伏および塑性変形機構が観察できることを示したことから，今後は同様な解析をより多く進めることによって，マイクロスケールにつなげる知見を得ることが期待できる．また，粒子モデルとフェーズフィールドモデルを融合した計算モデルを提案した．これに実際の粒界とマクロ力学特性をリンクさせれば，マルチスケールな解析が可能となると期待できる．新材料の開発にはこのようなモデルが不可欠であり，社会的な意義も大きいといえる．

Research Products

• [Journal Article] A Molecular Dynamics Study on the Effects of Lattice Defects on the Phase Transformation from BCC to FCC Structures (2019)
  • Author(s): Takuya Uehara
  • Journal Title: Materials Sciences and Applications Volume: 10 Issue: 08 Pages: 543-557
  • DOI: 10.4236/msa.2019.108039
  • Peer Reviewed / Open Access
• [Journal Article] Molecular Dynamics Simulation of Grain Refinement in a Polycrystalline Material under Severe Compressive Deformation (2017)
  • Author(s): Takuya Uehara
  • Journal Title: Materials Sciences and Applications Volume: 8 Issue: 12 Pages: 918-932
  • DOI: 10.4236/msa.2017.812067
  • Peer Reviewed / Open Access
• [Presentation] Molecular Dynamics Simulation of the Influence of Lattice Defects on Bcc-Fcc Phase Transformation (2019)
  • Author(s): Takuya Uehara
  • Organizer: The 13th Int. Conf. on the Mechanical Behaviour of Materials
  • Int'l Joint Research
• [Presentation] Molecular dynamics simulation of the initiation of plastic deformation in nanocrystalline material (2018)
  • Author(s): Takuya Uehara
  • Organizer: The 9th International Conference on Computational Methods
  • Int'l Joint Research
• [Presentation] 粒子充填構造の幾何学的特徴と安定性に関するシミュレーション (2018)
  • Author(s): 上原拓也
  • Organizer: 日本材料学会第3回マルチスケール材料力学シンポジウム
• [Presentation] 多面体構造形成過程のフェーズフィールドシミュレーション (2018)
  • Author(s): 上原拓也
  • Organizer: 日本機械学会第31回計算力学講演会
• [Presentation] Molecular dynamics simulation of microstructural change in a polycrystalline FCC metal under compression (2017)
  • Author(s): Takuya Uehara
  • Organizer: XIV Int. Conf. on Computational Plasticity
  • Int'l Joint Research