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.

Abstract: A method and apparatus for repairing composite skin structures from a blind side. The method includes using an elongated patch with a compression jig to hold the patch in place while the patch is either bonded in place or fixed in place with countersunk fasteners or both. The patch, when used on composite materials, is constructed and positioned so as to have the same anisotropic load-carrying characteristics as does the material to be repaired. A blind side repair can be completely made in the field without requiring extensive facilities.

Abstract: An improved method and apparatus for preventing buckling of thermoplastic composite laminates during an autoclaving process. Edge strips are placed around the periphery of the laminate to prevent the vacuum bag of the autoclave from making contact with the edges of the laminate when the autoclave is pressurized. As a result, the vacuum bag is prevented from imparting inwardly directed forces to the edges of the laminate which could otherwise cause the laminate to buckle.