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The role of annealing in determining the yielding behavior of glasses under cyclic shear deformation [Physics]
Proceedings of the National Academy of Sciences of the United States of America ( IF 11.1 ) Pub Date : 2021-04-20 , DOI: 10.1073/pnas.2100227118
Himangsu Bhaumik 1 , Giuseppe Foffi 2 , Srikanth Sastry 3
Affiliation  

Yielding behavior in amorphous solids has been investigated in computer simulations using uniform and cyclic shear deformation. Recent results characterize yielding as a discontinuous transition, with the degree of annealing of glasses being a significant parameter. Under uniform shear, discontinuous changes in stresses at yielding occur in the high annealing regime, separated from the poor annealing regime in which yielding is gradual. In cyclic shear simulations, relatively poorly annealed glasses become progressively better annealed as the yielding point is approached, with a relatively modest but clear discontinuous change at yielding. To understand better the role of annealing on yielding characteristics, we perform athermal quasistatic cyclic shear simulations of glasses prepared with a wide range of annealing in two qualitatively different systems—a model of silica (a network glass) and an atomic binary mixture glass. Two strikingly different regimes of behavior emerge. Energies of poorly annealed samples evolve toward a unique threshold energy as the strain amplitude increases, before yielding takes place. Well-annealed samples, in contrast, show no significant energy change with strain amplitude until they yield, accompanied by discontinuous energy changes that increase with the degree of annealing. Significantly, the threshold energy for both systems corresponds to dynamical cross-over temperatures associated with changes in the character of the energy landscape sampled by glass-forming liquids.



中文翻译:

退火在决定玻璃在循环剪切变形下的屈服行为中的作用 [物理学]

在计算机模拟中使用均匀和循环剪切变形研究了无定形固体的屈服行为。最近的结果将屈服描述为不连续的转变,玻璃的退火程度是一个重要的参数。在均匀剪切下,屈服应力的不连续变化发生在高退火状态,与屈服是逐渐的差退火状态分开。在循环剪切模拟中,随着接近屈服点,相对较差退火的玻璃逐渐变得更好退火,在屈服时具有相对适度但明显的不连续变化。为了更好地理解退火对屈服特性的作用,我们在两种性质不同的系统中对经过大范围退火制备的玻璃进行了无热准静态循环剪切模拟——二氧化硅模型(网络玻璃)和原子二元混合物玻璃。出现了两种截然不同的行为方式。在屈服发生之前,随着应变幅度的增加,退火不良的样品的能量会朝着独特的阈值能量发展。相比之下,退火良好的样品在屈服之前没有显着的能量随应变幅度变化,伴随着不连续的能量变化,随着退火程度的增加而增加。重要的是,两个系统的阈值能量对应于与玻璃形成液体采样的能量景观特征变化相关的动态交叉温度。

更新日期:2021-04-13
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