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 $S_2$, where $S_1$ and $S_2$ are the stiffness of the springs and $\mathit{\eta }$ is the viscoelastic constant of the dashpot