Abstract Concentrated soft materials like molten chocolate often has the ambiguity of behaving like a solid or a liquid depending on the external constraints. Determination of the constitutive relation is often unreliable and consequently the yield stress value too. This difficulty of determining yield stress, particularly when using a standards protocol such as the IOCCC for chocolate, is a consequence of the presence of wall slip. Assessment of slip velocity using Yoshimura and Prud'homme's method most often leads to erroneous results. We propose to tackle this problem by using an easy and reliable methodology applied to a commercial chocolate in a melted state with, as equipment, a plate-plate rotational rheometer. This method allows precise determination of the yield stress value, the constitutive relation and the slip velocity versus the shear stress. Furthermore, it provides an explanation to the apparent Newtonian plateau and thickening behavior of the raw flow curve.

中文翻译：

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确定熔融巧克力滑移速度、屈服应力和本构关系的准确方法

摘要 像熔融巧克力这样的浓缩软材料，根据外部约束，往往具有像固体或液体一样的模糊性。本构关系的确定通常是不可靠的，因此屈服应力值也是如此。确定屈服应力的这种困难，特别是在使用巧克力 IOCCC 等标准协议时，是壁滑的存在的结果。使用 Yoshimura 和 Prud'homme 的方法评估滑移速度最常导致错误的结果。我们建议使用一种简单可靠的方法来解决这个问题，该方法适用于熔融状态的商业巧克力，并使用板-板旋转流变仪作为设备。这种方法可以精确确定屈服应力值，本构关系和滑移速度与剪切应力的关系。此外，它为原始流动曲线的明显牛顿平台和增稠行为提供了解释。