Predicting plasticity of amorphous solids from instantaneous normal modes.
Predicting plasticity of amorphous solids from instantaneous normal modes.
复制标题
从瞬时简正模态预测非晶固体的塑性。
作者：
I. Kriuchevskyi;T. Sirk;A. Zaccone
我们通过将瞬时简正模态 (INM) 的概念扩展到变形系统，提出了非晶固体变形和塑性的数学描述，这使我们能够保留应变对振动态密度 (VDOS) 的影响。从玻璃弹性和粘弹性的非仿射晶格动力学 (NALD) 描述出发，我们通过考虑剪切应变有限值下的应变相关切线模量，制定了大变形的线性响应理论。 （非仿射）切线剪切模量是根据不同应变值下的仿射应变构型的 VDOS 计算得出的。通过分析在玻璃的静态（未变形）快照上发现的仿射应变，会产生富含软低能模式以及不稳定模式（负特征值）的配置，否则如果让系统在应变后完全松弛，这些配置就会完全“被冲走”并丢失。该过程与NALD的结构一致。变形状态的 INM 谱可以对模型玻璃的应力-应变曲线进行分析预测。粗粒聚合物玻璃的非热准静态剪切的预测和模拟之间显示出良好的无参数定量一致性。
We present a mathematical description of amorphous solid deformation and plasticity by extending the concept of instantaneous normal modes (INMs) to deformed systems, which allows us to retain the effect of strain on the vibrational density of states (VDOS). Starting from the nonaffine lattice dynamics (NALD) description of elasticity and viscoelasticity of glasses, we formulate the linear response theory up to large deformations by considering the strain-dependent tangent modulus at finite values of shear strain. The (nonaffine) tangent shear modulus is computed from the VDOS of affinely strained configurations at varying strain values. The affine strain, found analytically on the static (undeformed) snapshot of the glass, leads to configurations that are rich with soft low-energy modes as well as unstable modes (negative eigenvalues) that are otherwise completely "washed out" and lost if one lets the system fully relax after strain. This procedure is consistent with the structure of NALD. The INM spectrum of deformed states allows for the analytical prediction of the stress-strain curve of a model glass. Good parameter-free quantitative agreement is shown between the prediction and simulations of athermal quasistatic shear of a coarse-grained polymer glass.
DOI：
10.1073/pnas.2000698117
发表时间：
2020-06-02
影响因子：
11.1
作者：
Galloway, K. Lawrence;Ma, Xiaoguang;Arratia, Paulo E.
通讯作者：
Arratia, Paulo E.