関連する実験動画
Updated: Jun 2, 2026
06:07
Studying Large Amplitude Oscillatory Shear Response of Soft Materials
Published on: April 25, 2019
固体4Heにおける回転,リラックス,切断のダイナミクスの相互作用
E J Pratt1, B Hunt, V Gadagkar
1Laboratory for Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA.
Science (New York, N.Y.)
|May 14, 2011
まとめ
研究者は,トルションオシレータ (TO) を使用して固体ヘリウム-4 (4He) のダイナミクスを研究した. 発見は,超固体は顕微鏡の刺激から生じ,明確な相変遷ではなく,以前の理論に異議を唱えることを示唆しています.
科学分野:
- 凝縮物質物理学 凝縮物質物理学
- 量子材料は,量子的な物質である.
背景:
- 固体ヘリウム-4 (4He) は,潜在的超固体性を含む異常な性質を示している.
- 固体4Heにおける興奮と移行の性質は,依然として激しい研究の対象となっている.
研究 の 目的:
- 固体4He.の回転とリラックスダイナミクスを調査する.
- 提案された超固体行動に関連するパラメータ範囲を調査するために.
- 固体4Heにおける観測された現象の顕微鏡的起源を解明する.
主な方法:
- 高感度トルションオシレータ (TO) 技術を活用した.
- 固体4Heのダイナミクスを様々な熱的,機械的条件でマッピングした.
- TO応答の温度-速度および温度-ストレスの依存性を分析した.
主要な成果:
- 熱的刺激と機械的刺激の両方によって生成されるTO運動に起因する顕微鏡刺激を特定した.
- リラクゼーション時間のスムーズな分岐が観察され,臨界超固体移行温度または速度に対する証拠がない.
- 超固体性に起因するTO反応は,シアストレスの生成した刺激と機械的に関連していることが実証されました.
結論:
- 固体4Heで観測された現象は,特定の顕微鏡刺激の生成に起因する.
- 結果は,超固体性に関連した反応は,明確な相転換からではなく,これらの興奮から生じることを示しています.
- この研究は,固体4Heの異なる刺激に対するダイナミックな反応に関する統一された理解を提供します.
関連する概念動画
01:18Transformation of Plane Stress
Studying stress transformation is essential in understanding how stress components within a material, like a cube under plane stress, change with rotation. This change is analyzed by considering a prismatic element within the cube. As the element rotates, the stress components acting on it—both normal and shearing stresses—change in magnitude and orientation. This change is quantified using trigonometric functions of the rotation angle, relating the forces acting on the rotated element's faces...
01:15Thin-Walled Hollow Shafts
In analyzing a thin-walled hollow shaft subjected to torsional loading, a segment with width dx is isolated for examination. Despite its equilibrium state, this segment faces torsional shearing forces at its ends. These forces are quantitatively described by the product of the longitudinal shearing stress on the segment's minor surface and the area of this surface, leading to the concept of shear flow. This shear flow is consistent throughout the structure, indicating a uniform distribution of...
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
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...
01:08Equation of Rotational Dynamics
Angular variables are introduced in rotational dynamics. Comparing the definitions of angular variables with the definitions of linear kinematic variables, it is seen that there is a mapping of the linear variables to the rotational ones. Linear displacement, velocity, and acceleration have their equivalents in rotational motion, which are angular displacement, angular velocity, and angular acceleration. Similar to the rotational variables, a mapping exists from Newton's second law of motion...
01:20Shearing Strain
The shearing strain represents a cubic element's angular change when subjected to shearing stress. This type of stress can transform a cube into an oblique parallelepiped without influencing normal strains. The cubic element experiences a significant transformation when exposed solely to shearing stress. Its shape alters from a perfect cube into a rhomboid, clearly demonstrating the effect of shearing strain. The degree of this strain is considered positive if it reduces the angle between the...