A nano-micro-macro mechanical model for the analysis of soft collagenous tissues

In this paper the mechanical response of soft collagenous tissues with regular fiber arrangement (RSCTs) is described by means of a nanoscale model and a two-step micro-macro homogenization technique. The non-linear collagen constitutive behaviour is modelled at the nanoscale by a novel approach accounting for entropic mechanisms as well as stretching effects occurring in collagen molecules. Crimped fibers are reduced to equivalent straight ones at the microscale and the constitutive response of RSCTs at the macroscale is formulated by homogenizing a fiber reinforced material. This approach is suitable for different RSCTs (such as tendon, periodontal ligament and aortic media) and results effective and accurate as proved by the excellent agreement between available experimental data and computed results, obtained relating model parameters directly with histological and morphological evidences.