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arXiv 0908.2167cond-mat.stat-mechcond-mat.mtrl-sci
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有限温度下应变非晶态固体中塑性事件的大小

Size of Plastic Events in Strained Amorphous Solids at Finite Temperatures

H. G. E. Hentschel, Smarajit Karmakar, Edan Lerner, Itamar Procaccia

摘要:

当非晶态固体在有限温度下处于固定的外部应变速率下时,我们解决了典型塑性流动事件的系统尺寸依赖性。对于在合理的应变率和低温下可进行数值模拟的系统尺寸,塑性事件的大小随系统尺寸而增长。然而,我们解释说,这必须是一个有限的尺寸效应;对于较大的系统存在两个交叉的长度尺度$ξ_1$和$ξ_2$,第一个由弹性时间尺度和第二个由热能尺度确定。对于线性尺度$L$大于这些尺度的系统,塑性事件的大小必须有界。对于尺寸为$L\gg ξ$的系统,必须存在同时发生的$(L/ξ)^d$不相关塑性事件。我们提出了一个标度理论,最终与温度和应变率的交叉尺度的依赖性。最后,我们将这些发现与温度和尺寸依赖的应力波动。我们评论的重要性,这些考虑的弹塑性理论。

英文摘要:

We address the system-size dependence of typical plastic flow events when an amorphous solid is put under a fixed external strain rate at a finite temperature. For system sizes that are accessible to numerical simulations at reasonable strain rates and at low temperatures the magnitude of plastic events grows with the system size. We explain however that this must be a finite size effect; for larger systems there exist two cross-over length-scales $ξ_1$ and $ξ_2$, the first determined by the elastic time-scale and the second by the thermal energy-scale. For system of linear size $L$ larger than any of these scales the magnitude of plastic events must be bounded. For systems of size $L\gg ξ$ there must exist $(L/ξ)^d$ uncorrelated plastic events which occur simultaneously. We present a scaling theory that culminates with the dependence of the cross-over scales on temperature and strain rate. Finally we relate these findings to the temperature and size dependence of the stress fluctuations. We comment on the importance of these considerations for theories of elasto-plasticity.

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