Figure 8.
Specific strength. Determination of specific strength (strength per density; σult/ρeff) eliminates the geometrical dependence on cross-sectional area (e.g. equilibrium radius) as the same volume used for virial stress (the fibre volume, VF) is used to calculate the effective density (ρeff); see equation (3.1). Plot of specific strength versus %g depicts the same qualitative trends as ultimate strength for each rg, supporting the assertion that contact and shear interlock between globules is a key mechanism in increasing strength. The values attained (from approx. 0.1 to 0.4 MN m kg−1) account for 10–40% the specific strength of silk (approx. 1.0 MN m kg−1), a significant addition regardless of %g. (Online version in colour.)