A constitutive model of human esophagus tissue with application for the treatment of stenosis

• Autores: David Sánchez Molina
• Directores de la Tesis: Gabriel Bugeda Castelltort (dir. tes.), Carlos Arregui Dalmases (dir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2013
• Idioma: inglés
• Tribunal Calificador de la Tesis: Francisco Javier Gil Mur (presid.), Guillermo Reyes Pozo (secret.), Carles Martín Fumadó (voc.)
• Materias:
  • Ciencias de la vida
    • Biofísica
      • Biomecánica
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • This dissertation is a research about the mechanical behavior of the human esophagus. This work is intended to be applied in the treatment of stenosis and other esophageal diseases that frequently require a procedure of forced dilation, that involves high pressures on the esophagus wall. This study proposes a constitutive model to simulate forced dilatations. This study includes the experimental characterization of the mechanical behavior of human esophagus. In addition, some theoretical questions and experimental issues were addressed and solved. This dissertation summarizes the previous work on esophageal tissues by other authors. Additionally, a short explanation about the microcontinuum theory developed in the last decades is given, as well as a summary of the general theory of nonlinear hyperelastic constitutive models (with large deformation). This study required extensive testing of esophageal tissue in order to characterize the in vitro mechanical behavior. The testing included mainly tensile tests and complementary inflation tests. Optical motion track analysis was used for accurate computation of the strains in the tissue. The results of the tests were used for adjusting the mechanical properties that characterize the mechanical behavior of esophagus in the proposed models of the literature. The statistical analysis of the data revealed, some significant correlations between anthropometric factors, such as the body mass index, and some mechanical properties were found in the analysis of the data. The typical values of the mechanical properties were used to perform some numerical finite element simulations based on the proposed models. In addition, a number of theoretical results were obtained concerning the residual stress and the predictions of statistical mechanics for a system of collagenous fibers inside a soft tissue. The main result is a constitutive non-linear microstretch anisotropic hyperelastic constitutive model with large deformations (and with residual stresses) to characterize the multi-layered tissue of human esophagus. This model is suitable for numerical simulation.