Comparison of open hole tension characteristics of high strength glass and carbon fibre-reinforced composite materials

An experimental study was carried out to determine the open hole tension (OHT) characteristics of carbon fibre-reinforced plastic (CFRP) and high strength S2-glass fibre-reinforced plastic (GFRP). Tests to failure and percentages of ultimate load were carried out and non-destructive techniques were used to map damage progression. It was found that the CFRP OHT specimens were stronger, while the GFRP OHT specimens had greater ultimate strain. However, damage progression mechanisms in the two material systems were very similar. This is in contrast with previous findings on E-glass composites, indicating that S2-glass FRP notched failure behaviour is closer to a high-performance CFRP. Higher levels of damage formation prior to failure were found to result in higher OHT strength (SOHT). Blocked- ply stacking sequences were found to give higher damage levels and SOHT than sub-laminate level stacking sequences, and similar trends were found when laminate thickness was reduced. Non-linear transverse behaviour in GFRP resulted in lower levels of matrix cracking in OHT specimen 90° plies, compared to CFRP, providing a barrier to the growth of stress relieving axial splits in 0° plies.