FABRICATION METHODS FOR UNIDIRECTIONAL AND CROSSPLY COMPOSITES WITH FIBER WAVINESS

New fabrication methods were developed to produce controlled fiber wav iness in unidirectional and crossply composites. Unidirectional wavy c omposites were fabricated by a tape-winding method and a three-step cu ring method. The tape-winding method consists of winding the prepreg t ape around a mandrel and enclosing the entire layup in a mold for curi ng. In the three-step curing method the middle layers and the outer la yers are partially cured into wavy and flat sublaminates, respectively and, thereafter, sandwiched with uncured prepreg between them and co- cured together. It was verified experimentally that the three-step cur ing method produces the same quality material as the standard curing m ethod. Crossply wavy composites were fabricated by inserting periodica lly 90 degrees strips between the middle 0 degrees layers and the 90 d egrees layers on either side of it.