A visco-hyperelastic constitutive model and its application to the intestine

The small intestine is known for exhibiting complex nonlinear and time-dependent properties, requiring a suitable visco-hyperelastic model to characterize it. In this paper, the development of the constitutive model is divided into two steps. In the first step, we use a generalized anisotropic structure-based model, which has previously been used to model a wide range of tissues, to describe the hyperelastic behavior of the intestine. In the second step, the Prony series is used to describe the viscoelastic behavior of the small intestine; thus, a model characterizing the nonlinear visco-hyperelasticity of the small intestine during large deformation is developed. To verify the accuracy of the model, we use rabbit small intestine for tension tests and relaxation tests performed at 37 degrees C. The coefficients of determination of the hyperelastic and viscoelastic parts of the constitutive model are greater than 0.99, which is superior to the representative models currently used. The development of the model in this paper is fundamental to the analysis of the interaction between the capsule endoscopy and the small intestine.

Automated summary

This paper proposes a visco-hyperelastic model to characterize the complex nonlinear and time-dependent properties of the small intestine. The model development consists of two steps: using a generalized anisotropic structure-based model to describe the hyperelastic behavior and employing the Prony series for the viscoelastic behavior. The developed model demonstrates superior accuracy compared to existing models, as confirmed by tension tests and relaxation tests on rabbit small intestine.