Aircraft components such as stringers have become complex in design and shape due to developing aircraft designs. The complexity of shape in combination with a need for decreased weight/strength ratios requires the use of alternate construction technologies. For this reason, aircraft designers have turned to the use of composite ply assemblies for the manufacture of aircraft stringers. In these manufacturing scenarios, a material ply impregnated with epoxy or similar substance is layed-up onto a mandrel shaped to generated the complex shape. The composite ply assembly is then cured to generate a composite component with the desired complex shape.
Present aircraft designs, however, can require complex contours and twists which can be difficult to implement with existing mandrel technology. Present mandrel assemblies utilize either metal fabricated mandrels or composite mandrel assemblies. Present metal fabricated mandrels are highly resistant and exhibit long life spans. It is difficult, however, to configure these metal mandrel assemblies into the desired complex contours and twists. The common metal mandrel is too stiff to be forced into these contours. The common approach, therefore, has been to turn to composite mandrels capable of being forced into a wider range of complex contours. Composite ply mandrels, however, are easily damaged and have a considerably limited lifespan compared to the metal counterparts. As such, their use undesirably impacts the cost and time involved with composite stringer manufacturing.
It would therefore be highly desirable to have an aircraft stringer lay-up assembly that combined the flexibility and utility of composite mandrel assemblies with the resiliency and cost effectiveness of metal fabricated mandrel assemblies.
USPTO Backgrounds
USPTO Backgrounds