非晶塑性细观模型的机械噪声相关的时效和剪切带行为
Mechanical noise dependent Aging and Shear Banding behavior of a mesoscopic model of amorphous plasticity
摘要：
我们讨论了一个简单的“Eshelby”非晶塑性介观模型的老化和本地化。假设塑性形变是通过一系列局部重组发生的。使用离散晶格上的机械场的离散化，局部重组被建模为局部滑移事件。局部屈服应力在空间上是随机分布的，在时间上是不变的。每一次塑性滑移都会引起一次长时间的弹性应力重分布。模仿老化的影响，我们专注于该模型的行为时，初始状态的特点是高局部屈服应力值的分布。一个戏剧性的本地化行为的影响：系统首先自发自陷阱，形成一个剪切带，然后才慢慢地扩大。“年龄”参数越高，塑性应变场越局部化。在应力场上计算的两次相关性随年龄参数的变化表现为时间发散。与屈服应力分布宽度相比，局部滑移事件（Eshelby奇异性的前因子）的振幅在这里充当有效的温度参数：滑移增量越低，局部化和去相关时间越高。
英文摘要：
We discuss aging and localization in a simple "Eshelby" mesoscopic model of amorphous plasticity. Plastic deformation is assumed to occur through a series of local reorganizations. Using a discretization of the mechanical fields on a discrete lattice, local reorganizations are modeled as local slip events. Local yield stresses are randomly distributed in space and invariant in time. Each plastic slip event induces a long-ranged elastic stress redistribution. Mimicking the effect of aging, we focus on the behavior of the model when the initial state is characterized by a distribution of high local yield stress values. A dramatic effect on the localization behavior is obtained: the system first spontaneously self-traps to form a shear band which then only slowly widens. The higher the "age" parameter the more localized the plastic strain field. Two-time correlation computed on the stress field show a divergent correlation time with the age parameter. The amplitude of a local slip event (the prefactor of the Eshelby singularity) as compared to the yield stress distribution width acts here as an effective temperature-like parameter: the lower the slip increment, the higher the localization and the decorrelation time.
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