arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1001.0918cond-mat.stat-mechcond-mat.soft
收藏

固体流动吗?

Do solids flow?

F. Sausset, G. Biroli, J. Kurchan

摘要:

固体与液体在本质上不同吗?为了诱导流动,必须施加有限的应力吗?或者,所有的固体只是在有限的时间尺度上看起来是刚性的,如果施加一个无穷小的剪切应力,最终会流动吗?令人惊讶的是,这些简单的问题是一个争论的问题,仍然缺乏明确的答案。在这里,我们表明,固体只是一个时间尺度依赖的概念:平衡态的物质,自发地打破平移不变性,例如晶体,流动,即使是一个无穷小的应力施加。然而,它们这样做的方式本质上不同于普通液体,因为它们的粘度发散为零的剪切应力与一个本质的奇点。我们发现一个超缓慢的减少的剪切应力作为剪切速率的函数,这解释了流变流动曲线中确定的表观屈服应力。此外,我们认为,一个交替剪切的频率$ω$和振幅$γ$应导致一个动态的相变线($ω$,$γ$)平面,从一个“流动”到一个“非流动”相。最后,我们将我们的结果应用到晶体,显示相应的微观过程导致流动和讨论可能的实验研究。

英文摘要:

Are solids intrinsically different from liquids? Must a finite stress be applied in order to induce flow? Or, instead, do all solids only look rigid on some finite timescales and eventually flow if an infinitesimal shear stress is applied? Surprisingly, these simple questions are a matter of debate and definite answers are still lacking. Here we show that solidity is only a time-scale dependent notion: equilibrium states of matter that break spontaneously translation invariance, e.g. crystals, flow if even an infinitesimal stress is applied. However, they do so in a way inherently different from ordinary liquids since their viscosity diverges for vanishing shear stress with an essential singularity. We find an ultra-slow decrease of the shear stress as a function of the shear rate, which explains the apparent yield stress identified in rheological flow curves. Furthermore, we suggest that an alternating shear of frequency $ω$ and amplitude $γ$ should lead to a dynamic phase transition line in the ($ω$,$γ$) plane, from a 'flowing' to a 'non-flowing' phase. Finally, we apply our results to crystals, show the corresponding microscopic process leading to flow and discuss possible experimental investigations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑