Oldroyd's 1946 formulation of the constitutive equation of yield stress fluids laid the foundation of modern rheology of yield stress fluids, by considering not just the simple shear behavior of yield-stress fluids in the plastic regime, but also by prescribing a simple expression for how they behave prior to yielding and a 3D expression for how they behave beyond yielding. We discuss the implications of Oldroyd's model, and the ways in which researchers have tested and refined his ideas. We also review the experimental methods that have been employed to test these implications, and to determine the rheological parameters it lays out. We finally discuss the impact of Oldroyd's model, and the future of investigations into what happens prior to yielding.

Oldroyd 于 1946 年提出的屈服应力流体本构方程奠定了现代屈服应力流体流变学的基础，不仅考虑了塑性状态下屈服应力流体的简单剪切行为，而且还给出了一个简单的表达式来说明它们如何屈服之前的行为和 3D 表达他们在屈服之外的行为。我们讨论了 Oldroyd 模型的含义，以及研究人员测试和完善他的想法的方式。我们还回顾了用于测试这些影响的实验方法，并确定了它列出的流变参数。我们最后讨论了 Oldroyd 模型的影响，以及对屈服之前发生的情况进行调查的未来。