Theoretical and experimental studies on the nonlinear mechanical property of tracheal cartilage.

The mechanical property of the trachea affects the flow in the airway and may contribute to the biological function of the lung. Like many other biological tissues, the tracheal cartilage is likely to be a nonlinear material. To investigate the nonlinearity of tracheal cartilage, Fung-type strain energy density function was used. A mathematical model for analyzing the deformation of tracheal cartilage was developed and a bending test on pig trachea was performed. By fitting the experimental data, the constants included in the strain energy density function were therefore determined. The experimental data shows that tracheal cartilage displays higher strength in compression than in extension. Fung-type strain energy density function can capture this nonlinear behavior very well, whilst the linear stress-strain relation cannot. This study contributes to a better understanding of the material of tracheal cartilage and further benefits to its mechanical behavior under physiological and pathological conditions.