Yielding of Hard-Sphere Glasses during Start-Up Shear
Yielding of Hard-Sphere Glasses during Start-Up Shear
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DOI：
10.1103/physrevlett.108.098303
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发表时间：
2012-03-02
影响因子：
8.6
通讯作者：
Petekidis, G.
中科院分区：
文献类型：
--
作者：
Koumakis, N.;Laurati, M.;Petekidis, G.
通过流变学、共聚焦显微镜和启动剪切过程中的布朗动力学模拟，研究了浓缩硬球悬浮液和玻璃，提供了微观结构、动力学和流变学之间的联系。微观结构的各向异性表现在延伸轴上，其中对分布函数的最大值在应力超调处呈现最小值。布朗松弛和剪切平流的相互作用以及可用的自由体积决定了结构的各向异性和应力超调的大小。剪切引起的笼内变形引起局部收缩，减少笼内扩散。最后，在稳定状态下的超扩散响应，具有最小的时间相关有效扩散系数，反映了连续的笼型破裂和改造。
Concentrated hard-sphere suspensions and glasses are investigated with rheometry, confocal microscopy, and Brownian dynamics simulations during start-up shear, providing a link between microstructure, dynamics, and rheology. The microstructural anisotropy is manifested in the extension axis where the maximum of the pair-distribution function exhibits a minimum at the stress overshoot. The interplay between Brownian relaxation and shear advection as well as the available free volume determine the structural anisotropy and the magnitude of the stress overshoot. Shear-induced cage deformation induces local constriction, reducing in-cage diffusion. Finally, a superdiffusive response at the steady state, with a minimum of the time-dependent effective diffusivity, reflects a continuous cage breakup and reformation.