Modeling and Identification of the Mechanical Properties of Achilles Tendon With Application in Health Monitoring

Abstract

In this study, we develop a modeling and experimental framework for multiscale identification of the biomechanical properties of the human Achilles tendon (AT). For this purpose, we extend our coarse-grained model of collagen fibrous materials with a chemomechanical model of collagen type I decomposition. High-temperature degradation of molecular chains of collagen in a water environment was simulated using a reactive molecular dynamics (MD) method. The results from MDs simulations allowed us to define the Arrhenius equation for collagen degradation kinetics and calculate the energy of activation together with the frequency factor. Kinetic coefficients obtained from a MD simulations were further used to provide better calibration of the a coarse grained (CG) model of collagen denaturation. For the experimental part of our framework, we performed a uniaxial tensile test of the human AT with additional use of digital image correlation (DIC) for ex vivo strain tracking. Using a different path of strain tracking, we were able to include the inhomogeneity of deformation and, therefore, regional variations in tissue stiffness. Our results, both in modeling and the experimental part of the study, are in line with already existing reports and thus provide an improved approach for multiscale biomechanical and chemomechanical studies of the human AT.