Post repair high velocity impact behaviour of carbon-glass hybrid composite: Experimental and numerical study

In this work post repair high velocity impact behaviour of carbon-glass hybrid composite was investigated. Two parent hybrid laminates(H1:G₂C₄G₂ and H2:C₂G₄C₂), two double sided patches (P1: G₂C₂ and P2: C₂G₂) and two single sided patches (P3: G₂C₄G₂ and P4: C₂G₄C₂)) were used in this study. The velocities in the range of 80-120 m/s were considered for this study. The effect of patch type and stacking sequence of patch plies on the impact resistance were studied. A 3D finite element model based on continuum damage mechanics approach was also developed to further understand the effect of the ratio of glass to carbon plies in a patch. The Hou damage initiation criteria and strain based damage evolution criteria were incorporated in the proposed numerical model. Overall, the P3 patch repair specimen performed better than all patch repaired specimens and the P2 patch repair specimen performed better than all double side patch repaired specimens. The P3 patch repaired specimen showed an 8% higher ballistic limit than the P2 repaired specimen patch. It was also observed that number of glass plies in the patch govern the damage development in the specimen and residual velocity of projectile.