Molecular-based nonlinear viscoelastic chemomechanical model incorporating thermal denaturation kinetics of collagen fibrous biomaterials

In this article, we propose a constitutive model for soft collagenous biomaterials that takes into account their thermal denaturation. We created a large strain viscoelastic material model of collagenous microfibrils. The stress-strain curves from the coarse-grained simulations of collagen microfibrils have been used to calibrate the proposed rheological constitutive model. This modeling framework allows to predict viscoelastic mechanical behavior of collagenous materials for strain rates ranging from static tests to 1e9 s−1. Moreover, we enhanced the proposed constitutive model using the kinetic theory, to calculate the influence of thermal denaturation on long term viscoelastic properties of collagen. The proposed model can be directly used in micro finite element models of collagenous biomaterials as it allows to calculate the biomechanical properties of those materials for physiologically relevant deformation rates. The model incorporates both changes of stiffness and a decrease in viscoelasticity of collagenous materials exposed to elevated temperatures (for example laser surgeries or thermal treatments). The achieved agreement with experimental data demonstrates that the molecular-based chemomechanical framework constitutes a powerful tool for prediction of stability and mechanical behavior of collagen-based biomaterials.