In vitro biaxial stress-strain response of human skin.

The development of new experimental methods and test equipment has permitted a study of the mechanical characteristics of unembalmed human cadaver skin. Excised tissue specimens were exposed to dynamic, biaxially applied displacements and forces in order to quantify the skin's anisotropic, viscoelastic stress-strain response. In addition to monotonically increasing displacement-time loadings, experiments were performed to measure the tissue's stress relaxation characteristics resulting from a suddenly applied displacement. Data are presented that demonstrate a nonlinear stress-strain relationship for the skin that is notably influenced by displacement boundary conditions imposed on the tissue specimen. Results indicate that the skin is a viscoelastic material whose mechanical loading response is dependent on the anatomic direction in which the strains are applied.