ABSTRACT
The materials in biology are always strongly nonlinear. Mechanical behaviors of soft tissues may be much different from those of such common materials as rubbers. Thus, sometimes it is very hard to find existing material models to show soft tissues. That forces users to develop their own hyperelastic laws in commercial software. ANSYS provides such a subroutine, called Userhyper, which requires the importation of derivatives of the strain-energy potential with respect to I 1, I 2, and J. In this chapter, soft tissues of the artery with the exponential form were implemented by Userhyper, in which the derivatives of the strain energy potential with respect to I 1, I 2, and J were programmed. After being validated by the Mooney-Rivlin material model, the developed Userhyper was applied to study the abdominal aortic aneurysm (AAA) model under blood pressure. Compared to the standard USERMAT, UserHyper is very easy to implement.
