Constitutive modeling of liver tissue: Experiment and theory

Mechanical models for soft organ tissues are necessary for a variety of medical applications, such as surgical planning, virtual reality surgery simulators, and for diagnostic purposes. An adequate quantitative description of the mechanical behavior of tissues requires adequate and accurate experimental data to be acquired and analyzed. We present results of three types of ex vivo tests on pig liver tissue, i.e. simple tension, unconfined compression and pure shear. A new constitutive model based on combined logarithmic and Ogden strain energy is proposed. The model accounts very well for observed non-linear stress-strain relations for full strain range of tension and compression and represents equally well the mechanical response of pure shear when strain is less than 35%.