论文标题
正常应力在蠕变动力学和生物聚合物凝胶失败中的作用
Role of normal stress in the creep dynamics and failure of a biopolymer gel
论文作者
论文摘要
我们通过同时动态光散射和流变学测量值研究了在恒定剪切负荷下生物聚合物凝胶破裂的延迟破裂。我们揭示了在凝胶过程中累积的正常应力的关键作用：所有最终在凝胶过程中断裂自动裂缝的样品，这是通过部分放松的正常应力与一系列显微镜塑料重排的爆发所揭示的那样。施加剪切应力后，弱化的凝胶在其微观动力学中显示出独特的特征，可预测宏观骨折的最多数千秒。断裂凝胶中的动力学比非压裂凝胶的动力学更快，并且表现出较大的时空波动。具有显着可塑性的空间局部区域最终会逐渐扩展，最终侵入整个样品触发宏观失败。
We investigate the delayed rupture of biopolymer gels under a constant shear load by simultaneous dynamic light scattering and rheology measurements. We unveil the crucial role of normal stresses built up during gelation: all samples that eventually fracture self-weaken during the gelation process, as revealed by a partial relaxation of the normal stress concomitant to a burst of microscopic plastic rearrangements. Upon applying a shear stress, weakened gels exhibit in the creep regime distinctive signatures in their microscopic dynamics, which anticipate macroscopic fracture by up to thousands of seconds. The dynamics in fracturing gels are faster than those of non-fracturing gels and exhibit large spatio-temporal fluctuations. A spatially localized region with significant plasticity eventually nucleates, expands progressively, and finally invades the whole sample triggering macroscopic failure.
