Experimental Characterization of Mode I Crack Resistance Curves of CFRP Laminates under Impact Loading

Abstract

Mode I crack resistance curves of CFRP (Carbon Fiber Reinforced Plastics) laminates were investigated using the W-DCB (Wedge-loaded Double Cantilever Beams) specimen and SHPB (Split Hopkinson Pressure Bars) system under impact loading, where the SWC (Stress Wave Control) technique was applied to reduce the effects of inertia force induced by the impact loading in the specimen. LSB (Local Strain Based) formula, where the dynamic energy release rate could be theoretically calculated from the surface strain of the specimen, was proposed to evaluate the mode I fracture toughness under impact loading. SST (Surface Strain Transition) analysis, where the dynamic crack growth behavior could be was discretely determined from the strain distribution of the specimen, was proposed to evaluate the mode I crack extension under impact loading. Finite element analyses considering the dynamic loading and crack extension demonstrated the validity of the evaluation method of crack resistance curves based on the LSB formula and SST analysis. Rate dependence of the mode I crack resistance curves of unidirectional CFRP laminates (T700S/2500, Toray) was experimentally investigated using the proposed method, where the mode I fracture toughness was not sensitive to the loading rate and crack extension.