Author(s)

T. Tsuta, T. Iwamoto & T. Fujimura

Abstract

An automatic loading and sensing system for obtaining in vivo multi-axial Pi-δi (i-1,2,...,) curves in facial skin of living humans has been developed. Once the Pi-δi curves are obtained through a series of experiments for respective directions (x-x, y-y, x-y,...,), then the constitutive parameters are identified by the least squares approach, using the analogy with the FEM computer model, so that the gap between the experimental Pi-δi curves and the FEM Pi-δi curves can be minimized in respective i-th directions by improving the physical parameters. Application to the forehead skins in actual humans aged 22 years and 54 years has been examined. Finally the constitutive parameters of facial muscles have also been identified. These results are applied to generate facial wrinkling and permanent wrinkling problems induced by aging. It is clarified that earlier wrinkling in older aged humans is mainly induced by the change in constitutive parameters. Keywords: in vivo skin constitutive model, sensing of multiaxial P- δ curve, analogy to FEM computer model, forehead skin, wire-driven remote loading hardware system, motion control system, least squares identification approach, some applications. 1 Introduction The combined contraction of about thirty kinds of facial muscles induces numerous types of facial expression and wrinkling. It induces permanent

Keywords

in vivo skin constitutive model, sensing of multiaxial P- δ curve, analogy to FEM computer model, forehead skin, wire-driven remote loading hardware system, motion control system, least squares identification approach, some applications.