Influence of fibre volume fraction on mode II interlaminar fracture toughness of glass/epoxy using the 4ENF specimen

Glass reinforced composites are used in many structural applications. Their fibre content can vary considerably according to the manufacturing route, typically from 30% to 70% by volume. This paper presents results from an experimental study of the influence of fibre volume fraction on the mode II interlaminar fracture toughness, GIIc, using the 4ENF (four point end notched flexure) specimen. Results show that GIIc increases with decreasing fibre content. This effect is caused by plastic deformation energy dissipation in the thicker resin-rich interlaminar layer in lower fibre content composites.