Heterogeneous relaxation dynamics in amorphous materials under cyclic loading.
Heterogeneous relaxation dynamics in amorphous materials under cyclic loading.
复制标题
DOI：
10.1103/physreve.87.052302
复制
发表时间：
2013-01
期刊：
影响因子：
--
通讯作者：
Nikolai V Priezjev
中科院分区：
文献类型：
--
作者：
Nikolai V Priezjev
利用分子动力学模拟研究了非晶玻璃材料在振荡剪切应变下的非均匀动力学行为。我们认为三维二元Lennard-Jones混合物远低于玻璃化转变温度。通过自重叠序参量和动态磁化率定量描述了结构弛豫和动力学非均匀性。我们发现，在足够小的应变振幅，均方位移表现出一个广泛的亚扩散平台和系统经历了约10（4）个周期几乎可逆的变形。在增加应变振幅时，以较短的时间间隔发生向扩散制度的过渡，并且松弛过程涉及大颗粒位移的间歇性爆发。粒子跳跃动力学和动态磁化率的详细分析表明，移动的粒子聚集成团簇，其尺寸在较大的应变幅增加。最后，在连续的时间间隔的颗粒迁移率之间的相关性表明，动态促进变得越来越明显，在较大的应变幅度。
Molecular dynamics simulations are performed to investigate heterogeneous dynamics in amorphous glassy materials under oscillatory shear strain. We consider three-dimensional binary Lennard-Jones mixture well below the glass transition temperature. The structural relaxation and dynamical heterogeneity are quantified by means of the self-overlap order parameter and the dynamic susceptibility. We found that at sufficiently small strain amplitudes, the mean square displacement exhibits a broad subdiffusive plateau and the system undergoes nearly reversible deformation over about 10(4) cycles. Upon increasing strain amplitude, the transition to the diffusive regime occurs at shorter time intervals and the relaxation process involves intermittent bursts of large particle displacements. The detailed analysis of particle hopping dynamics and the dynamic susceptibility indicates that mobile particles aggregate into clusters whose sizes increase at larger strain amplitudes. Finally, the correlation between particle mobilities in consecutive time intervals demonstrates that dynamic facilitation becomes increasingly pronounced at larger strain amplitudes.