Large amplitude oscillatory shear of pseudoplastic and elastoviscoplastic materials
Large amplitude oscillatory shear of pseudoplastic and elastoviscoplastic materials
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DOI：
10.1007/s00397-009-0403-7
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发表时间：
2010-02-01
期刊：
影响因子：
2.3
通讯作者：
McKinley, Gareth H.
中科院分区：
文献类型：
--
作者：
Ewoldt, Randy H.;Winter, Peter;McKinley, Gareth H.
我们探讨应变控制的大振幅振荡剪切（LAOS）变形的效用，识别和表征表观屈服应力响应的弹粘塑性材料。我们的方法强调的视觉表示的LAOS应力响应的Lissajous曲线的框架内的应变，应变率，应力作为坐标轴，结合相应的极限环行为的定量分析。这种方法使我们能够探索如何表征屈服响应的材料特性取决于应变振幅和变形频率。采用经典本构模型（包括纯粘性Carreau模型和弹性Bingham模型）描述了大振幅振荡剪切下材料的假塑性和弹塑性响应特征。引入了一个新的参数--理想塑性耗散率，用于唯一识别塑性行为。实验结果表明，两种复合流体，假塑性剪切稀化黄原胶溶液和弹粘塑性反相乳化钻井液。LAOS测试协议和相关的材料测量提供了复杂流体的屈服行为的流变指纹，该流变指纹可以在由变形的幅度和时间尺度定义的Pipkin图的域内被压缩地表示。
We explore the utility of strain-controlled large amplitude oscillatory shear (LAOS) deformation for identifying and characterizing apparent yield stress responses in elastoviscoplastic materials. Our approach emphasizes the visual representation of the LAOS stress response within the framework of Lissajous curves with strain, strain rate, and stress as the coordinate axes, in conjunction with quantitative analysis of the corresponding limit cycle behavior. This approach enables us to explore how the material properties characterizing the yielding response depend on both strain amplitude and frequency of deformation. Canonical constitutive models (including the purely viscous Carreau model and the elastic Bingham model) are used to illustrate the characteristic features of pseudoplastic and elastoplastic material responses under large amplitude oscillatory shear. A new parameter, the perfect plastic dissipation ratio, is introduced for uniquely identifying plastic behavior. Experimental results are presented for two complex fluids, a pseudoplastic shear-thinning xanthan gum solution and an elastoviscoplastic invert-emulsion drilling fluid. The LAOS test protocols and the associated material measures provide a rheological fingerprint of the yielding behavior of a complex fluid that can be compactly represented within the domain of a Pipkin diagram defined by the amplitude and timescale of deformation.