Abstract: We reduce core crush and ply wrinkling in composite honeycomb sandwich structure by preventing slipping of tiedown plies relative to the mandrel and to one another during autoclave curing. We produce superior panels with lighter weights, improved mechanical properties, and more predictable structural performance. The method involves applying a film adhesive to the tiedown plies in the margin of the part outside the net trim line. During heating of the autoclave and prior to the application of high pressure to the composite structure, the film adhesive cures to form a strong bond between the plys and to the mandrel. When pressure is applied, the tiedown plys are locked together and to the mandrel to prevent slippage between any layers in the panel.

Abstract: Resin flow into the cells of a honeycomb core in sandwich structures is eliminated by using an unsupported film adhesive, a barrier layer, and a scrim supported adhesive layer between the composite laminate and the core. Superior panels with lighter weights, improved mechanical properties, and more predictable structural performance result by keeping resin in the laminate rather than losing it to the core cells.