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 ft was close to the measurement from the three-point bending tests with the relative error < 6 %.

Automated summary

This study analyzed the fracture performance of a composite material with highly heterogeneous and anisotropic microstructures using a boundary effect model. By testing notched specimens with different parameters, the maximum load and crack growth of the material were determined. The results showed noticeable delamination crack growth around the notch tip in the material.