Elasticity of soft tissues in simple elongation

Abstract

Elasticity of living soft tissues is strongly nonlinear. Based on experimental results on rabbits'' mesentery, a theoretical framework is presented in which the elastic properties of soft tissues can be described. The mathematical formulation works well in reducing published data on the series element of the heart and striated muscles, and the skin. In simple elongation the tensile stress was nearly an exponential function of the strain in the lower stress range. Although the material worked with was a definite deformation of highly nonlinear materials, the elastic property of soft tissues in tension could be expressed quite simply in most cases. It is necessary, however, to give up the usual practice of trying to characterize the elasticity of a tissue by a representative Young''s modulus, because this modulus varied over a very wide range, which was often zero at vanishing stress, and increased linearly as the stress increased, and therefore was meaningless unless the exact stress level was specified. New physical constants recommended are: the slope and curvature at the origin of the curve of dT/dX vs. T, where T stands for tension and [gamma] stands for the extension ratio, and the tensile stress T* , (based on the original cross-sectional area)at a specific value of the extension ratio [gamma]*.