Many industries, such as the biotechnology, food, and beauty industries, require noninvasive methods for quantifying material stiffness. One such method is the indentation test, which is particularly useful in evaluating the mechanical characteristics of soft materials. However, it is difficult to identify mechanical characteristics of the distinct layers of layered materials such as human skin due to their physical integration with one another. There is particular interest in evaluating the softness of the stratum corneum (the outermost layer of skin) in the cosmetics industry, where the effect of cosmetics should be restricted to this outermost layer. The purpose of this study was to develop a method to determine the elasticities and thicknesses of discrete layers in a layered material by using an indentation test. This paper discusses the results of this indentation test derived via the finite element method (FEM). Here, the finite element (FE) model is constructed by a layered structure of flat surfaces with given Young’s moduli. The FEM results suggest the existence of a law among the elasticities and layer thicknesses of a layered material.

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