Department of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, Israel.
Phys Rev Lett. 2010 Jan 15;104(2):025501. doi: 10.1103/PhysRevLett.104.025501. Epub 2010 Jan 11.
We address the system-size dependence of plastic flow events when an amorphous solid is put under a fixed external strain rate at a finite temperature. For small system sizes at low strain rates and 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 crossover length scales xi{1} and xi{2}, the first determined by the elastic time scale and the second by the thermal energy scale. For systems of size L>>xi there must exist (L/xi){d} uncorrelated plastic events which occur simultaneously. We present a scaling theory that culminates with the dependence of the crossover 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 elastoplasticity.
我们研究了在有限温度下，固定外应变速率下非晶固体的塑性流动事件的系统尺寸依赖性。在低应变速率和低温下的小系统尺寸下，塑性事件的大小随系统尺寸的增大而增大。然而，我们解释说，这必须是有限尺寸效应；对于更大的系统，存在两个交叉长度尺度 xi{1} 和 xi{2}，第一个由弹性时间尺度决定，第二个由热能尺度决定。对于尺寸为 L>>xi 的系统，必然存在（L/xi){d}个不相关的同时发生的塑性事件。我们提出了一个标度理论，最终得出了交叉尺度与温度和应变速率的关系。最后，我们将这些发现与应力涨落的温度和尺寸依赖性联系起来。我们评论了这些考虑对于弹塑性理论的重要性。
