Applying a Stiffened Stitched Concept to Shear-Loaded Structure

摘要

NASA and The Boeing Company have worked to develop new low-cost, lightweightrncomposite structures for aircraft. A stitched carbon-epoxy material systemrnwas developed to reduce the weight and cost of transport aircraft structure, first inrnthe NASA Advanced Composites Technology (ACT) Program in the 1990’s andrnnow in the Environmentally Responsible Aviation (ERA) Project. By stitchingrnthrough the thickness of a dry carbon fiber material prior to cure, the need forrnmechanical fasteners is almost eliminated. Stitching also provides the benefit ofrnreducing or eliminating delaminations, including those between stiffener flangesrnand skin. The stitched panel concept used in the ACT program used simple bladestiffenersrnas stringers, caps, and clips. Today, the Pultruded Rod Stitched EfficientrnUnitized Structure (PRSEUS) concept is being developed for application tornadvanced vehicle configurations. PRSEUS provides additional weight savingsrnthrough the use of a stiffener with a thin web and a unidirectional carbon rod at therntop of the web which provides structurally efficient stiffening. Comparisonsrnbetween stitched and unstitched structure and between blade-stiffened and rodstiffenedrnstructure are presented focusing on a panel loaded in shear. Shear loadingrnis representative of spar loading in wing structures.