Flexural tests and analysis of notched specimens of glass fiber reinforced composite

Fracture of notched Specimens of laminar glass fiber reinforced composite is quasi-brittle and with noticeable delamination crack growth around the notch tip, as indicated by the non-linear load–deflection curve close to the peak fracture load. In order to analyze the fracture performance of the composite with highly heterogeneous and anisotropic microstructures, the boundary effect model (BEM) considering the composite layered structures and damage along and perpendicular to the notch was adopted in this study. Around 90 notched three-point bending specimens with the span from 40 to 90 mm, plate thickness around 10 mm, the initial notch depth from 3 to 6 mm were tested and the maximum load P_max values were recorded. The average fiber ply or layer thickness C_ch was the characteristic microstructure modelled by BEM for both the crack-tip damage zone length (crack-bridging) and width (delamination). Both the tensile strength f_t and fracture toughness K_IC were determined from the notched bending tests. Direct tensile tests were also conducted and the measured tensile strength f_t was close to the measurement from the three-point bending tests with the relative error < 6 %.