Rate Effects on Mode I Interlaminar Fracture Toughness in Composite Materials

Abstract

The Double Cantilever Beam (DCB) test geometry was utilized to investigate the rate ef fects on Mode I interlaminar fracture toughness in graphite/PEEK and graphite/epoxy composites. The tests were performed over a range of crosshead speeds from 4.2 × 10^-6 to 6.7 × 10 ^-1 m/s. The results indicate that the toughness of both material systems is rate sensitive. The Mode I interlaminar fracture toughness of the graphite/PEEK material decreases from 1.5 to 0.35 kJ/m² over five decades of opening rate. The fracture toughness of the graphite/epoxy material decreases from 0.18 to 0.04 kJ/m² over four decades of load ing rate.