Thermoplastic seam welds

A method for making a thermoplastic fusion weld joint in thermoplastic composite, honeycomb core sandwich structure without autoclave processing during formation of the joint, comprising the steps of:

• (a) laying up upper and lower, left and right laminated face sheets having a plurality of plies of fiber-reinforced thermoplastic matrix resin;
• (b) positioning separator plies along edges of the face sheets to define fingers that will overlap and interleaf and that will form the joint to create an interleaf split of fiber-reinforced laminated composite fingers adapted for forming a double staggered interleaf joint;
• (c) consolidating the face sheets to produce composites substantially free of volatiles or porosity with consolidated fingers along the edges where the joint will be made;
• (d) bonding the upper and lower face sheets, respectively, to a honeycomb core with a resin rich layer on the surface of the face sheet that contacts the honeycomb core to form the left and right honeycomb core sandwich structure;
• (e) removing the separator plies;
• (f) interleaving respective fingers of the left and right face sheets above and below the core to define double staggered interleaf joints;
• (g) optionally, positioning a metal foil between the core and each face sheet beneath the fingers in the region of the joint to reinforce the joint;
• and
• (h) melting and mixing the resin between fingers in the joints to form thermoplastic fusion welds and to complete double staggered interleaf joints above and below the honeycomb core.