Figure 3.

Comparison of the fibril stress (σ), interfibrillar shear stress (τ), and fibril displacements (u) along the unit cell length in the elastic and plastic shear lag models with increasing applied tissue strain (from row 1 to 3). (Row 1: A–D) Initially, when L_s is less than L_c, there is less interfibrillar sliding (i.e., smaller region where u₁ ≠ u₂) in the plastic model compared to the elastic model (ε_uc = 0.5%). (Row 2: E–H) As the applied tissue strain increases, L_s becomes similar to L_c and the amount of interfibrillar sliding is approximately the same between the two models. The fibril stress distribution and point at which the interfibrillar shear stress approaches zero are also very similar between the two models (ε_uc = 1.4%). (Row 3: I–L) At higher applied strains, L_s continues to increase until L_s = L/4, where the interfibrillar sliding and shear stress occur across the entire fibril length, maximally loading the fibrils. In contrast, the elastic model produces identical distributions of stresses and displacements since the characteristic length over which loads are transmitted between fibrils (L_c) remains constant. Model parameters: E_f = 700 MPa, r = 85 nm, ϕ = 0.7, τ_p = 0.275 kPa, G = 1 Pa, L = 10 mm.