Quasi-Static Analysis of Stress and Strain Distribution in Vocal Folds Under Constant Loading Conditions

This study presents a detailed biomechanical analysis of vocal cords using the M5 model, focusing on their viscoelastic properties and dynamic behavior during phonation. The research investigates the interactions between airflow, tissue deformation, and acoustic conditions to understand the complex mechanisms underlying sound production. The primary components analyzed are the lamina propria, ligament, and body, each displaying distinct responses to applied pressures ranging from 1 to 3 kPa. Key results reveal that the lamina propria is the most stress-concentrated region, particularly under higher frequencies, highlighting its critical role in absorbing mechanical loads and maintaining structural integrity. Displacement analysis shows anisotropic behavior, with higher flexibility in the X-direction (up to 3.5 mm) and alternating positive and negative values in the Y-direction, with maximum magnitudes of approximately -1 mm in the ligament. Nonlinear stress-deformation behavior was observed, with stresses rising sharply to 9 kPa when deformations exceeded 3 mm under a 3 kPa load. Additionally, natural vibration frequencies significantly affect stress distribution, potentially causing resonances that may lead to pathologies such as dysphonia. The conclusions emphasize the importance of the viscoelastic properties of the lamina propria in enabling efficient sound modulation and stress absorption while preventing structural damage.