Damage resistance and damage tolerance of dispersed CFRP laminates: Effect of ply clustering

In this paper, the effect of introducing ply clustering in a composite stacking sequence on the damage resistance and damage tolerance of CFRP composite plates is investigated. Three stacking sequences are considered. First, a baseline laminate with conventional 0 degrees, +/- 45 degrees and 90 degrees orientations and without ply clustering. The other two laminates are dispersed laminates with orientations not limited to the conventional ones. In one of them, four layers of 0 degrees fiber orientation are clustered together at the specimen mid-plane, whereas in the last configuration, two clusters of two layers of 0 degrees fiber orientation are introduced at the specimen top and bottom surfaces. The in-plane and the out-of-plane stiffness of the dispersed laminates match within 2\% those of the baseline laminate. Ant Colony Optimization algorithm is used to select the stacking sequences with the desirable clustering and stiffness constraints. The results obtained demonstrate that introducing clustering had a negative effect on the maximum peak load recorded at different impact energies and also on the projected delamination area. Regarding damage tolerance, the residual compressive strength can be improved up to 30\% with ply clustering. (C) 2013 Elsevier Ltd. All rights reserved.