Hybrid effect in multi-directional carbon/glass composites

The hybrid effect is the enhancement in the failure strain of the low strain material in a hybrid composite compared with the failure strain of the same material in a non-hybrid composite. It has been well established that in unidirectional carbon/glass composites under tension with the carbon layer as the low strain material, the hybrid effect depends mainly on the carbon layer thickness. In this work, experimental and numerical results are presented to show that in multidirectional composite laminates with two separated 0° carbon plies, the interaction between the 0° carbon layers and the presence of matrix cracking in the adjacent layers can significantly change the carbon layer fragmentation strain and consequently modify the observed hybrid effect. The interaction between 0° carbon plies is analysed using the induced strain increment after the fragmentation of one of the 0° carbon plies. The results show that the layups with lower interaction between the two 0° carbon plies and those with no matrix cracking in the neighbouring layers have a higher hybrid effect.