Anti-symmetric laminates for improved consolidation and reduced warp of tapered C-sections

This paper challenges the conventional use of symmetric stacking sequences by proposing fully uncoupled anti-symmetric laminates that simultaneously improve consolidation and reduce warp of tapered laminates. A demonstrator C-section laminate with an anti-symmetric stacking sequence has been designed to eliminate coupling between in-plane and out-of-plane deformation. Results are compared with a conventional, symmetric baseline. The two laminate designs were deposited on a male tool using automated fiber placement and final de-bulk and cure were performed in a single autoclave operation. It is postulated that long continuous plies spanning a tapered region can inhibit consolidation in unidirectional material when they are not equidistant from the tool surface. The ply termination strategy of the anti-symmetric laminate mitigates this effect. It has been found that the antisymmetric demonstrator achieved better consolidation compared with the baseline symmetric demonstrator. The results also show for the first time, that the level of warping exhibited by the anti-symmetric laminate is approximately 50% lower than the symmetric baseline.