For the proportion of the curvature that is not developable (Complex curvature), the in-plane deformation should be promoted trough tension. This tension is applied by the flexible nozzle due to friction between the blankets and the charge and could be adjusted using the pressure applied by the forming bladder or additional pressure actuation, depending of the shape of the part.
Depending on the persistence of the non-developable curvature, the approach to address the deformation needed is different:
Short accumulated curvature
For short accumulated curvature, like a joggle, the in-plane deformation of the fibers, inside the limits of the tolerance, is performed by applying tension only.
Short accumulated curvature
For longer cumulative curvatures, the deformation of the fibers is higher than the charge could absorb. In these cases, the solution is the use of overlaps or butt-splice of the 0º plies. The process produce the tension needed to promote the stretch of the overlap area. In order to preserve the accuracy of the length of the part, “control length” continuous tows are placed in the non-stretching edges of the overlapping areas.
