Modeling the rheology of thixotropic elasto-visco-plastic materials
Modeling the rheology of thixotropic elasto-visco-plastic materials
复制标题
触变弹粘塑性材料的流变学建模
DOI：
10.1122/1.5049136
复制
发表时间：
2019
影响因子：
3.3
通讯作者：
J. Tsamopoulos
中科院分区：
文献类型：
--
作者：
S. Varchanis;G. Makrigiorgos;P. Moschopoulos;Y. Dimakopoulos;J. Tsamopoulos
为了描述触变弹粘塑性 (TEVP) 材料的宏观流变行为，必须考虑其微观结构中发生的现象。为此，我们将 Saramito 的 EVP 材料张量本构模型与触变性相结合，扩展了各向同性硬化的思想，并与运动硬化 (KH) 相结合，以解释背应力。我们使用一个标量变量来描述任何情况下的结构水平，并使用修改后的阿姆斯特朗-弗雷德里克 KH 方程，从而提供控制表观屈服应力动态的规则。材料粘度、屈服应力和背应力模量具有对结构参数的非线性依赖性，使模型能够利用单个结构参数进行准确预测。为了避免剪切流和拉伸流中的非物理应力演化，我们提出了一种修改后的背应力本构方程，该方程使应力张量的分量保持有界。新模型的预测与简单流变流动中的实验数据和先前提出的 TEVP 模型的预测进行了比较，包括稳态和步进剪切测试、流动反转、间歇步进测试、小振幅振荡剪切 (SAOS) 和大幅度振荡剪切。在大多数情况下，所提出的模型比其他模型更准确地再现这些实验数据，突出了其预测能力。此外，SAOS 表明，通过 Saramito 模型引入粘塑性必然会在线性应变状态下将 G'' 降低至零。这需要在固态下进行模型调整。最后，我们检查了所提出的单轴伸长模型，并得出结论，将这种流动纳入此类系统的流变表征和建模中非常重要。为了描述触变弹粘塑性 (TEVP) 材料的宏观流变行为，必须考虑其微观结构中发生的现象。为此，我们将 Saramito 的 EVP 材料张量本构模型与触变性相结合，扩展了各向同性硬化的思想，并与运动硬化 (KH) 相结合，以解释背应力。我们使用一个标量变量来描述任何情况下的结构水平，并使用修改后的阿姆斯特朗-弗雷德里克 KH 方程，从而提供控制表观屈服应力动态的规则。材料粘度、屈服应力和背应力模量具有对结构参数的非线性依赖性，使模型能够利用单个结构参数进行准确预测。为了避免剪切流和拉伸流中的非物理应力演化，我们提出了一种修改后的背应力本构方程，该方程使应力张量的分量保持有界。新模型的预测是...
To describe the macroscopic rheological behavior of thixotropic elasto-visco-plastic (TEVP) materials, phenomena that take place in their microstructure must be accounted for. To this end, we couple the tensorial constitutive model by Saramito for EVP materials with thixotropy, extending the ideas of isotropic hardening, and with kinematic hardening (KH), to account for back stresses. We use a scalar variable that describes the level of structure at any instance and a modified Armstrong–Frederick KH equation, thus providing rules governing the dynamics of the apparent yield stress. The material viscosity, yield stress, and back stress modulus feature a nonlinear dependence on the structural parameter, enabling the model to make accurate predictions with a single structural parameter. To avoid unphysical stress evolution in both shear and extensional flows, we propose a modified back stress constitutive equation that keeps the components of the stress tensor bounded. The predictions of the new model are compared to experimental data and predictions of previously proposed TEVP models in simple rheometric flows, including steady and step-shear tests, flow reversal, intermittent step tests, small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear. In most cases, the proposed model reproduces more accurately these experimental data than the other models, highlighting its predictive capabilities. Moreover, SAOS illustrates that introducing viscoplasticity via the Saramito model necessarily reduces G″ to zero in the linear strain regime. This calls for model adjustments in the solid state. Finally, we examined the proposed model in uniaxial elongation and concluded that it is important to include this flow in the rheological characterization and modeling of such systems.To describe the macroscopic rheological behavior of thixotropic elasto-visco-plastic (TEVP) materials, phenomena that take place in their microstructure must be accounted for. To this end, we couple the tensorial constitutive model by Saramito for EVP materials with thixotropy, extending the ideas of isotropic hardening, and with kinematic hardening (KH), to account for back stresses. We use a scalar variable that describes the level of structure at any instance and a modified Armstrong–Frederick KH equation, thus providing rules governing the dynamics of the apparent yield stress. The material viscosity, yield stress, and back stress modulus feature a nonlinear dependence on the structural parameter, enabling the model to make accurate predictions with a single structural parameter. To avoid unphysical stress evolution in both shear and extensional flows, we propose a modified back stress constitutive equation that keeps the components of the stress tensor bounded. The predictions of the new model are co...