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弹性、几何与屈曲

Elasticity, Geometry and Buckling
课程网址: http://videolectures.net/kolokviji_kosmrlj_elasticity_geometry_bu...  
主讲教师: Andrej Košmrlj
开课单位: 普林斯顿大学
开课时间: 2017-01-09
课程语种: 英语
中文简介:
在本次座谈会中,我们将介绍几何形状如何影响固体薄壳的力学性能,以及屈曲不稳定性如何改变材料中周期性微观结构的几何形状。利用基于统计力学的方法,我们发现固体薄板的随机形状波动和热激励显著改变了其力学性能。受这种波动影响的板材更难弯曲,但更容易拉伸、压缩和剪切。在球壳中,热波动也有效地产生负表面张力,这相当于施加外部压力。我们发现小的球壳是稳定的,但对于足够大的球壳,这种热产生的“压力”变得足够大,足以压碎球壳。最后,我们展示了固态物理的方法如何帮助我们推断弯曲周期性微结构的几何结构。屈曲不稳定性会改变微观结构的对称性,包括自发的手征对称性破缺,这会极大地改变材料的性质。
课程简介: In this colloquium we present how geometrical shape affects the mechanical properties of thin solid shells and how buckling instabilities change the geometry of periodic microstructures in materials. Using methods rooted in statistical mechanics, we find that random shape fluctuations and thermal excitations of thin solid sheets significantly modify their mechanical properties. Sheets subject to such fluctuations are much harder to bend, but easier to stretch, compress and shear. In spherical shells thermal fluctuations also effectively produce negative surface tension, which is equivalent to applying external pressure. We find that small spherical shells are stable, but for sufficiently large shells this thermally generated “pressure” becomes big enough to crush spherical shells. Finally, we show how methods from solid-state physics can help us deduce the geometry of buckled periodic microstructures. Buckling instabilities can change the microstructure symmetries, including a spontaneous chiral symmetry breaking, which drastically modifies the material properties.
关 键 词: 几何形状; 力学性能; 屈曲不稳定性
课程来源: 视频讲座网
数据采集: 2022-03-28:zkj
最后编审: 2022-03-28:zkj
阅读次数: 14