Dynamic mode II interlaminar fracture toughness of electrically modified carbon/epoxy composites

This work investigates mode II delamination toughness of unidirectional carbon/epoxy laminates with enhanced electrical conductivity through different loading rates. The electrical modification was realized through interleaving a tough veil loaded with silver nanowires (AgNWs) into the laminate. A benchmarking against non-modified carbon/epoxy laminates was carried out to examine the influence of the modification of the material delamination toughness. End-notched flexure (ENF) specimens were subjected to loading rates ranging from quasi-static up to 5.5 m/s using servo-hydraulic load frame and modified Hopkinson bar apparatus. The strain energy release rate was determined by applying the compliance based beam method (CBBM), ruling out a necessity of the crack length measurement, generating complete R-curves. The findings demonstrated a notable increase, nearly 79%, on the critical strain energy release rate of the modified laminates, in comparison with that of the reference ones, carried out under the quasi-static loading condition. With respect to the influence of loading rate on mode II interlaminar fracture toughness values, the non-modified carbon/epoxy laminates demonstrated a marginal increase, whereas showing no notable effect on the interleaved ones.