Recent studies have shown that rheological material functions that can be linked to structural measures are defined in terms of the recoverable and unrecoverable strains [for example, Lee et al., Phys. Rev. Lett. 122, 248003 (2019)]. In this study, we explore the consequences of applying these ideas to transient nonlinear rheological tests, using new material functions including an elastic modulus and a flow viscosity defined in terms of the recoverable strain and the rate of acquisition of unrecoverable strain, respectively. These material functions, based on recoverable and unrecoverable strains (rather than total strain), are defined in the same way independent of the test protocol and provide the viscoelastic properties of a material in a clear and succinct way without requiring a priori knowledge of the constitutive model. At short times, we observe that for a self-assembled wormlike micellar solution, the new material functions exhibit a constant (plateau) modulus and a constant (zero-shear) viscosity independent of the applied shear rate, even under conditions that eventually lead to nonlinear responses. This observation quantitatively corroborates the intuitive picture of material deformation that when the material is close to equilibrium, it responds according to its linear viscoelastic material properties for both linear and nonlinear deformations. The fundamental, universal, and unifying nature of these new transient measures are showing promise in explaining a range of phenomena, including the Payne effect for filled polymers and yield stress materials, as well as suggesting new improved dimensionless groups for more accurate flow diagnosis. This work lays the foundation for measuring material functions that are directly related to the material structure and are agnostic of the testing protocol.

中文翻译：

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回顾瞬变流变材料功能的基础：可恢复应变测量的见解

最近的研究表明，可以与结构度量相关的流变材料功能是根据可恢复和不可恢复的应变来定义的（例如，Lee等，Phys。莱特牧师 122，248003（2019）]。在这项研究中，我们探讨了将这些想法应用于瞬态的后果非线性流变测试，使用新的材料功能，包括分别根据可恢复应变和不可恢复应变的获取率定义的弹性模量和流动粘度。这些材料功能基于可恢复和不可恢复的应变（而不是总应变），以相同的方式定义，与测试规程无关，并以清晰简洁的方式提供了材料的粘弹性质，而无需先验本构模型的知识。在很短的时间内，我们观察到，对于自组装的蠕虫状胶束溶液，即使在最终导致变形的条件下，新材料的功能也表现出与所施加的剪切速率无关的恒定（平稳）模量和恒定（零剪切）粘度。非线性响应。该观察结果定量地证实了材料变形的直观图景，即当材料接近平衡时，它会根据其线性粘弹性材料特性对线性变形和非线性变形做出响应。这些新的临时措施的基本，通用和统一的性质在解释一系列现象方面显示出了希望，包括填充聚合物和屈服应力材料的佩恩效应，并建议新的改进的无量纲组，以进行更准确的流量诊断。这项工作为测量与材料结构直接相关且与测试规程无关的材料功能奠定了基础。