Thèse d'Alberto Terzolo

Composed of collagen, elastin and muscular fibrous networks, human vocal folds are soft larygeal multilayered tissues owning remarkable vibro-mechanical performances. However, the impact of these tissues’ histological specifications on their overall mechanical properties remains elusive. Thereby, this work proposes a micro-mechanical model able to describe the 3D fibrous architecture and the surrounding matrices of the vocal-fold sublayers, and to predict their multiscale behavior accordingly. For each layer, the model parameters were identified using available histo-mechanical data, including their quasi-static response to physiological loading conditions (ie, tension, compression and shear). The evolution of microscopic descriptors such as fiber kinematics, deformation and interactions was simulated. Regardless of the loading mode, it was shown how macroscale nonlinear, viscoelastic and anisotropic tissue responses are inherited from fiber scale phenomena. Original scenarios of micro-mechanisms were also predicted for a large variety of loading conditions at various rates : (i) low-frequency cyclic and multiaxial loadings upon finite strains ; (ii) high-frequency small (SAOS) and large (LAOS) deformation oscillatory shear. In particular, the major role of 3D fiber orientation in tension, steric hindrance in compression, and the matrix contribution in shear was highlighted. Finally, the micromechanical model was implemented in a finite element (FE) code, yielding to a prior 3D simulation of vocal fold transient dynamics with relevant histo-mechanical properties. This work paves the way toward future multiscale simulations of vocal fold vibrations, accounting for various 3D fibrous healthy and pathological architectures.