Stress and strain localization in stretched collagenous tissues via a multiscale modelling approach

Mechanobiology of cells in soft collagenous tissues is highly affected by both tissue response at the macroscale and stress/strain localization mechanisms due to features at lower scales. In this paper, the macroscale mechanical behavior of soft collagenous tissues is modeled by a three-levels multiscale approach, based on a multi-step homogenization technique from nano up to the macroscale. Nanoscale effects related to both intermolecular cross-links and collagen mechanics are accounted for, together with geometric nonlinearities at the microscale. Moreover, an effective submodeling procedure is conceived in order to evaluate the local stress and strain fields at the microscale, that is around and within cells. Numerical results, obtained by using an incremental finite element formulation and addressing stretched tendinous tissues, prove consistency and accuracy of the model at both macro and microscale, confirming also the effectiveness of the multiscale modeling concept for successfully analyzing physiopathological processes in biological tissues.