Figure 4

(a) High-speed camera images of the impact process of the pure epoxy resin, and Bm- and Ap-SFRPs with 30 vol.% or 60 vol.% silk reinforcement; (b) Schematics of the fracture morphologies after impact tests and photographs of the fractured samples from top and side views. (i) matrix resin’s brittle fracture; (ii) 30 vol.% Bm-SFRP’s semi-ductile fracture; ductile fracture of (iii) 60 vol.% Bm-SFRP and (iv) 30 vol.% Ap-SFRP; (v) ductile response of 60 vol.% Ap-SFRP. (c) Sketch map of mechanisms for ductile responses to impact on the left, including epoxy resin fracture, fibre pull-out and fracture, interfacial debonding; SEM images on the right showing contributions on a fracture surface: epoxy fracture, fibre fracture and pull-out are highlighted contributions in 30 vol.% Bm-SFRP; and interfacial debonding is highlighted as a significant contribution in 30 vol.% Ap-SFRP.