The net force is enough to predict the motion of an object, but to predict its deformation, the distribution of the force inside the object should be known. In the continuum electromechanics, various expressions are used to calculate the electric forces acting on a dielectric object. The Kelvin and the Korteweg–Helmholtz forces are the most common electric body forces. The net force resulting from both of these “forces” is equal, but the distribution of these two forces inside a dielectric material is different because the expressions of both these forces lose their physical manifestation in the derivation process. This article is primarily aimed at revealing the common mistakes that are made when deriving volumetric force density. Then, the concept of an infinitesimal particle and external electric field is introduced. By using this concept, the electric force density inside a dielectric material is uniquely determined irrespective of the force expression, which is shown analytically and numerically.

中文翻译：

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介电材料内部开尔文和 Korteweg-Helmholtz 力密度的相等性

净力足以预测物体的运动，但要预测其变形，则应知道物体内部的力分布。在连续体机电学中，使用各种表达式来计算作用在介电物体上的电力。Kelvin 和 Korteweg-Helmholtz 力是最常见的电动体力。这两个“力”产生的净力是相等的，但是这两个力在介电材料内的分布是不同的，因为这两个力的表达式在推导过程中失去了它们的物理表现。本文主要旨在揭示推导体积力密度时常犯的错误。然后，介绍了无穷小粒子和外部电场的概念。通过使用这个概念，