that toughness is no longer equal to the area under the stress-strain
curve [29]. At the same time, fibre strength values remained
virtually unchanged, with or without the knots, indicating that
there was little fibre fragilization in the sliding phase (SEM images
of the knots in the three fibres are also shown in Fig. 5). The influence
of fibre diameter was relatively small, although results
seemed to indicate that smaller diameters could provide better
strength but smaller stiffness. On the other hand, therewas a strong
dependence on knot tightening, as can be seen in Fig. 5: a high
energy-dissipation stress plateau (close to 50% the fibre strength)