Fig. 1.

Standard linear solid model representing collagen fiber behavior, with ${\mathit{\epsilon }}_{\mathrm{f}}$ the total fibril strain, ${\mathit{\epsilon }}_{\mathrm{v}}$ the dashpot strain, and ${\mathit{\epsilon }}_{\mathrm{e}}$ the strain in spring ${\text{S}}_2$. Where ${\text{S}}_1$ and ${\text{S}}_2$ are the stiffness of the springs and $\mathit{\eta }$ the viscoelastic constant of the dashpot