Mechanical analysis of the small and large intestine using an experimental and computational approach [English translation]

This thesis aimed to experimentally and computationally characterize the mechanical behavior of human intestinal tissues, with particular focus on ileum, colon, and colon with taenia samples. The study of intestinal biomechanical properties is relevant to improving the understanding of the response of gastrointestinal soft tissues under different loading conditions and to the subsequent development of numerical models capable of reproducing their mechanical behavior.
The analyzed samples were obtained from portions of human intestine collected from patients undergoing surgery and were tested at the Laboratory of Mechanics of Biological Materials of the University of Padua. The experimental campaign included membrane bending, tensile, compression, and insufflation tests. Membrane bending tests represented the main focus of the experimental analysis, enabling comparison among the different tissue origins through force–displacement curves, stiffness parameters, peak force values, and percentage energy loss. Tensile and compression tests were instead used to investigate additional aspects of the tissue mechanical response and to provide data for constitutive parameter identification.
The experimental data were processed using MATLAB, and representative parameters were obtained, including initial and linear stiffness, elastic moduli, characteristic stress and strain values, toughness, relaxation percentages, energy loss, and compliance. The results highlighted the nonlinear and viscoelastic behavior of the analyzed tissues, with differences associated with anatomical origin and loading mode.
In particular, membrane bending tests revealed different responses among ileum, colon, and colon with taenia in terms of both stiffness and energy dissipation.
The experimental data were also used to develop finite element computational models of the membrane bending and insufflation tests using Abaqus/CAE 2025. Numerical modeling made it possible to compare the simulated response with the experimental one and to assess the ability of the models to reproduce the mechanical behavior of intestinal tissues.
Overall, this work provides an integrated mechanical characterization of human intestinal tissues and establishes an experimental and numerical basis for future developments in the biomechanical modeling of the gastrointestinal tract.