Handy-Device Development of Softness Measurement by Indentation Imitating Palpation for Evaluation of Elasticity and Visco-Elasiticity

Abstract

Spherical indentation testing is studied to evaluate the viscoelasticity of soft materials like human body. Here, the Hertzian contact theory is functionally extended to evaluate indentations for the thin tissues. In the expansions, the technique used for evaluating the thickness of finite specimens is first explained by analyzing the experimental results of indentations. Then, the viscoelasticity of soft materials with finite thickness is theoretically derived by defining an equivalent indentation strain for the analysis of the indentation process. The expansions are examined to evaluate its reliability by applying them to measure the viscoelasticity of some soft materials. Furthermore, this technology is applied to the elasticity investigation of the human body. Especially, the measurement results of viscoelastic characteristics of the body of human body are shown and the availability of developed device is discussed to reveal the deformation mechanics of human body in this report.