Delamination resistance of composites using inclined Z-pins

This study explores the behaviour of inclined Z-pins inserted in End Loaded Split (ELS) specimens at areal densities of 0.22% and 0.40%. The study has shown an increase in the fracture toughness when Z-pins are better aligned with the load vector (inclined) compared to the conventional, orthogonally inserted Z-pins. Brittle, catastrophic failure occurs when the inclined Z-pins are misaligned with the load vector. Given the difficulty in predicting localised load vectors in complex structures, specimens with ±θ configuration are tested and compared to conventional non-inclined Z-pin configurations. The results for the areal densities tested in this study show minimal differences in delamination resistance between the two configurations. However, there is some evidence to suggest that at high areal densities, the ±θ configuration is likely to produce higher GIIC values compared to the conventional non-inclined Z-pin configuration.