Mixtures of solid particles and Newtonian fluids such as water-clay suspensions are prepared for industrial usage and have many engineering applications. Different methods, setups, and protocols are available to characterize rheological behavior of these aqueous suspensions. In this study, large amplitude oscillatory shear (LAOS) protocols are considered as the main goal for the first time to examine non-linear rheological behavior of sepiolite suspensions. Four types of sepiolite clays and a commercial bentonite clay as reference were used to prepare fresh water-clay suspensions. Viscoelastic non-linearities of suspensions were studied as a function of strain and strain-rate using Lissajous–Bowditch curves and non-linear quantitative parameters. Discovery Hybrid Rheometer (DHR-II) was used in oscillation sweep tests for measuring non-linear properties. Impact of frequency on the evolution of LAOS properties was also investigated by constructing Pipkin diagrams. Bentonite suspension an had ability of keeping its elastic characteristics at higher strains compared to sepiolite clays indicating that bentonite clay yielded more flexible and structurally stable suspension. Sepiolite suspensions presented higher elastic stiffness (gel-strength) compared to bentonite suspension at all frequencies. Strong correlation in viscous non-linear parameters indicated viscous dominant behavior for all clay suspensions in the non-linear regions. It was also demonstrated that there is some tendency of shear-thickening behavior, particularly more notable for bentonite suspension under viscous deformation. It is postulated that the reason is hidden behind the structural differences of bentonite (platelets like) and sepiolite (fiber like) clays. Although both clays are members of smectite group, their structures and viscosity build mechanisms are quite different.

中文翻译：

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大振幅振荡剪切作用下水-粘土悬浮液的流变行为

固体颗粒和牛顿流体的混合物（如水-粘土悬浮液）可用于工业用途，并具有许多工程应用。不同的方法、设置和协议可用于表征这些水性悬浮液的流变行为。在这项研究中，大振幅振荡剪切 (LAOS) 协议首次被认为是检查海泡石悬浮液非线性流变行为的主要目标。四种类型的海泡石粘土和作为参考的市售膨润土用于制备淡水-粘土悬浮液。使用 Lissajous-Bowditch 曲线和非线性定量参数，研究了作为应变和应变率函数的悬浮液的粘弹性非线性。Discovery 混合流变仪 (DHR-II) 用于振荡扫描测试以测量非线性特性。还通过构建皮普金图研究了频率对 LAOS 特性演变的影响。与海泡石粘土相比，膨润土悬浮液能够在更高的应变下保持其弹性特性，这表明膨润土产生了更柔韧和结构稳定的悬浮液。在所有频率下，与膨润土悬浮液相比，海泡石悬浮液表现出更高的弹性刚度（凝胶强度）。粘性非线性参数的强相关性表明非线性区域中所有粘土悬浮液的粘性主导行为。还表明存在一些剪切增稠行为的趋势，特别是在粘性变形下的膨润土悬浮液中更为显着。据推测，原因隐藏在膨润土（片状）和海泡石（纤维状）粘土的结构差异之后。尽管两种粘土都是蒙脱石族的成员，但它们的结构和粘度建立机制却大不相同。