Figure 6.
Mechanism of fibre deformation and fibril stress distribution. Representative model snapshots (a) of fibre subject to uniaxial deformation, 20%g and rg = 1.50r0 at ɛ = 0 (equilibrium; (i)), ɛ = 10% (ii), ɛ = 30% (iii) and ɛ = 50% (iv), with corresponding virial stress distribution (b). A selection of four pulled individual fibrils that initially extend one-half the fibre length is highlighted. Owing to the staggered and discontinuous fibril arrangement (figure 5), fibril sliding initiates at approximately ɛ > 10%. In the stress distributions, we see a shear-lag effect, where a finite length of fibril is required to build up the stress transfer. Shorter fibril lengths build up less stress. When stress is increasing, the slope of the stress distribution correspondingly increases (e.g. from ɛ = 10% to 30%), until a maximum stress level is reached, and the slope distribution is maintained along the fibril, whereas the fibrils themselves slip along the fibre axis (e.g. from ɛ = 30% to 50%). To determine total stress, the virial stress contributions of all fibrils are summed (equation (2.5)) and taken over the representative volume. (Online version in colour.)