Composite Skin Pre-forming with Flexible Substrate Tension
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Solution Overview
Problem
The construction and assembly of large and complex composite structures, such as airplane fuselages, are time-consuming and costly due to the serial process of forming support structures and applying composite fibers around a layup mandrel, necessitating improved systems and methods for forming a composite skin.
Innovation Solution
The method involves attaching a charge of composite material to a flexible substrate, deforming it to conform to a non-planar pre-forming surface while maintaining tension parallel to the substrate interface, and controlling deformation forces to prevent separation, allowing for the formation of a non-planar skin surface contour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a serial process is used to form support structures and apply composite fibers around a layup mandrel, then the composite structure can be assembled with proper support, but the assembly time becomes significant and costs increase
Solution Approach 1:
The process is divided into distinct phases: pre-forming the composite charge on a flexible substrate, then deforming it onto the layup mandrel. This segmentation allows parallel preparation of composite charges while the mandrel is being prepared, reducing overall assembly time while maintaining structural integrity through controlled deformation.
Solution Approach 2:
Composite charges are pre-formed on flexible substrates before being applied to the layup mandrel. This preliminary action allows the composite material to be prepared in advance with proper layering and orientation, then quickly deformed and applied to the mandrel, significantly reducing on-site assembly time while ensuring proper support structure formation.
2Shape
If composite material is deformed to conform to a non-planar pre-forming surface, then a complex skin contour is achieved, but the composite material may wrinkle or form voids if tension is not maintained
Solution Approach 1:
The flexible substrate's mechanical properties are carefully selected to maintain appropriate tension in the composite material during deformation. By controlling the substrate's flexibility and the deformation rate, the composite charge conforms to complex non-planar contours without wrinkling or void formation, achieving both complex shaping and high surface quality.
Solution Approach 2:
A flexible substrate acts as an intermediary between the composite charge and the pre-forming mandrel. This substrate maintains tension on the composite material during deformation, allowing the charge to conform to complex non-planar surfaces without direct contact with the mandrel, thereby preventing wrinkles and voids while achieving the desired skin contour.
3Productivity
If the composite charge is separated from the flexible substrate after deformation, then the final skin is obtained, but separation may cause defects if the composite material is not properly maintained in tension
Solution Approach 1:
The flexible substrate maintains continuous tension on the composite charge throughout the deformation and holding phases. This continuous tension prevents wrinkles and voids from forming during the critical deformation process, ensuring high skin quality before the final separation from the substrate to obtain the finished skin.
Data Source
AI summary
Systems and methods of forming a skin for a composite structure and composite structures including the same. The systems and methods include operatively attaching a charge of composite material to a flexible substrate to define a composite-substrate assembly. The systems and methods further include deforming the composite-substrate assembly by conforming the composite-substrate assembly to a non-planar pre-forming surface of a pre-forming mandrel to define a non-planar skin surface contour on the charge of composite material. The systems and methods further include maintaining the charge of composite material in tension in a direction that is parallel to an interface between the charge of composite material and the flexible substrate during the deforming.