Fig. 3.

Fitting the strain energy density function parameters using uniaxial mechanical test data from a isolated myocyte (Brady 1984) and b individual collagen fibril (Shen et al. 2008). Dots: data points of the experimental measurements. Line: stress–strain relationship with the best-fit parameter values. Stress: first Piola Kirchhoff stress. Strain: Green-Lagrange strain. Tangent stiffness: $\frac{d\text{PK}1}{d\lambda }$ where λ is the stretch