ストレスによる穀物境界移動の実験的観測
T J Rupert1, D S Gianola, Y Gan
1Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
Science (New York, N.Y.)
|December 19, 2009
まとめ
この研究は,ナノ結晶アルミニウムの粒子の境界が静的ではなく,ストレス下では活発に移動し,粒子の成長を促進することを明らかにしています. これは,粒子の境界を単なるプラスチック変形の障害として見る伝統的な見解に異議を唱える.
科学分野:
- マテリアルサイエンス 材料科学
- 固体力学 固体力学とは
- ナノテクノロジー ナノテクノロジー
背景:
- 結晶材料におけるプラスチック変形は,変位運動に依存する.
- 穀物の境界線は,通常,変位運動の障壁として作用します.
- 伝統的に,粒子の境界は機械的に静的な構造と考えられています.
研究 の 目的:
- ストレス駆動による穀物境界移動を実験的に調査する.
- ナノ結晶アルミニウム薄膜における粒子の成長を調べる.
- ストレスとストレスの濃縮物が穀物の成長に及ぼす影響を決定する.
主な方法:
- ストレス/ストレスの濃縮器を備えたナノ結晶アルミニウム薄膜の製造.
- 施されたストレス下における穀物の境界行動の実験的調査.
- 穀物の成長動態の分析. 穀物の成長動態の分析.
主要な成果:
- 観察されたストレス駆動の穀物境界移動は,穀物成長として表れています.
- 切断ストレスが穀物境界の動きを積極的に駆動することを実証した.
- 穀物の成長に対するストレスとストレスのパラメータの相対的重要性を定量化した.
結論:
- 穀物の境界線は静的な障害ではなく,積極的に移動する可能性があります.
- 発見は,最近の分子動力学シミュレーションと理論的予測を裏付けています.
- プラスチック性における粒子の境界に関する従来の理解に挑戦する.
さらに関連する動画
11:03An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
09:00Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography
Published on: September 29, 2019
関連する概念動画
01:24Stress-Strain Diagram - Ductile Materials
The stress-strain relationship in ductile materials such as structural steel or aluminium is intricate and progresses through several stages. When a specimen is loaded, it initially exhibits a linear length increase, depicted by a steep straight line on the stress-strain diagram. It indicates the material is elastically deforming and will return to its original shape once unloaded. However, when a critical stress value is reached, plastic deformation begins. This stage sees substantial...
01:24Stress-Strain Diagram - Brittle Materials
Brittle materials, including glass, cast iron, and stone, exhibit unique characteristics. They fracture without considerable change in their elongation rate, indicating that their breaking and ultimate strength are equivalent. Such materials also show lower strain levels at the point of rupture. The failure in brittle materials predominantly results from normal stresses, as evidenced by the rupture created along a surface perpendicular to the applied load. These materials do not display...
01:21Plastic Behavior
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and reloaded.
01:20Elastic Strain Energy for Shearing Stresses
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
01:15Stress: General Loading Conditions
To grasp the intricacy of real-world conditions where multiple loads are applied simultaneously to a structure, one might visualize a section passing through a specific point within a body, aligned parallel to the xy plane. This section is subjected to various forces, including original loads, normal forces, and shearing forces.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes.
01:10Stress-Strain Diagram
A stress-strain diagram is a crucial tool that graphically displays a material's mechanical characteristics. This diagram is derived from a tensile test performed on a carefully prepared cylindrical specimen. The specimen has two gauge marks inscribed on its central part, and the distance between these marks is known as the gauge length. The cylindrical specimen is placed in a testing machine, which applies an increasing centric load. As this load grows, so does the gauge length. This change in...