Fig. 2
Tensile properties of composites. a Typical tensile engineering stress–strain curves, b modulus and specific tensile modulus, c strength and specific tensile strength, and d elongation and breaking energy. Note that the breaking energy is calculated as the area under the stress–strain curve and the unit is converted from MPa to MJ m−3 for easy comparison with the literature. e Direct comparison of tensile stress–strain behaviour of pure epoxy resin, two reinforcement fibres, 69 vol.% CFRP and 51 vol.% SFRP. f Comparison of the tensile modulus and strength of the HFRP composites with increasing silk volume composition. The dashed lines indicate the expected values from the rule of mixtures (Eq. (1)). The silk volume compositions of 8C2S, 5C5S and 2C8S were, respectively, calculated as 15%, 42% and 74%. The error bars represent the standard deviation of measured means
