Historically, construction and/or assembly of a composite structure on an inner mold line (IML) layup mandrel, which also may be referred to herein as an inner mold line tool, a layup mandrel, and/or an IML tool, is a serial process that involves sequentially forming a plurality of support structures, such as stringers and/or spacers, on an outer surface of the layup mandrel, followed by locating a continuous, or at least substantially continuous, length of composite fibers around the outer surface of the layup mandrel to form a skin of the composite structure. This locating may be accomplished by wrapping the length of composite fibers around the outer surface of the layup mandrel, such as by rotating the layup mandrel with respect to a layup head that dispenses the length of composite fibers and/or by rotating the layup head relative to the layup mandrel.
Generally, the support structures are formed from a plurality of plies, or layers, of a composite material, such as a pre-preg material, and each layer of the plurality of layers may be applied individually and/or sequentially to the outer surface of the layup mandrel. Similarly, the skin typically includes a plurality of layers, with each layer of the plurality of layers being applied individually and/or sequentially to the outer surface of the layup mandrel.
As composite structures become larger and more complex, such as may be the case for composite barrel assemblies for an airplane fuselage, the time required to perform the above-described serial processes becomes significant. In addition, a cost of layup mandrels for large and/or complex composite structures is substantial. Thus, there exists a need for improved systems and methods for assembling a skin of a composite structure.
USPTO Backgrounds
USPTO Backgrounds