Fig. 3 | Nature Communications

Fig. 3

From: Stress-induced plasticity of dynamic collagen networks

Fig. 3

Bulk relaxation kinetics of collagen matrices. a The normalized elastic energy per fiber 〈H〉 over the course of relaxation of a model network. Black: sum of bending and stretching energy. Red: bending energy. Blue: stretching energy. All three curves are normalized by the total energy per fiber at t = −20 min. The network is sheared to 20% at t = −20 min, and released at t = 0. Inset: The network configuration after 20 min of relaxation (t = 1200 s). The fibers are color-coded according to the bending energy per unit length of each fiber H b , normalized by the ensemble average 〈H b 〉. b Simulated strain decay kinetics with 20% initial strain and varying dwell times T d  = 1, 2, 6, 10, 16, and 20 min. The dashed lines are fits to a single exponential. c Experiments show strain relaxation kinetics ε(t)−ε(∞) depend on the initial strain, and at small initial strains, the relaxation follows a single exponential function. Here ε(∞) is approximated by the strain measured after 15 min of relaxation, Supplementary Fig. 16 for results with extended relaxation time. d Experiments show strain relaxation kinetics depends on the dwell time T d . Colors of the symbols (blue to green) correspond to the increasing dwell time of 1, 2, 4, 7, 10, 15, and 20 min. Red lines are fit to double-exponential functions ε(t) = a exp(−t/τ v ) + b exp(−t/τ p ) + ε r . Here τ v is independent of dwell time T d , τ p , and ε r are allowed to vary with T d . Inset: zoom-in to the initial phase of the relaxation. e The plastic time scale τ p as a function of dwell time T m . f The residual strain ε r as a function of dwell time T d . Error bars in e, f are means and standard deviations from eight different samples

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