Foamable Media Repair for Composite Structures
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Solution Overview
Problem
The repair of composite structures, such as composite sandwich and laminate panels, is time-intensive, complex, and requires skilled labor, often involving material removal and replacement, which is undesirable for aerospace applications due to aesthetic and aerodynamic concerns.
Innovation Solution
A method using expandable foamable media is introduced, where a repair cavity is created in the composite structure, filled with foamable media comprising a polymer matrix and foaming agents, and expanded to restore the structure's properties, minimizing material removal and labor requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional repair methods (scarf repairs, doubler patches) are used, then structural integrity can be restored, but the repair process becomes time-intensive and complex
Solution Approach 1:
The patent changes the physical state of the repair material from solid/pre-formed (traditional patches) to a foamable medium that can be injected and expanded in-situ. The foamable media undergoes a phase change from liquid/suspension to expanded foam, allowing the repair to be performed without time-consuming material removal and replacement operations, thus reducing repair time while maintaining structural integrity.
Solution Approach 2:
The foamable media is designed to self-expand and self-secure within the repair cavity without requiring external form factors or complex assembly procedures. The material automatically fills the cavity and bonds to the surrounding structure as it expands, eliminating the need for manual positioning of multiple components and reducing overall repair time.
2Reliability
If material removal and replacement operations are performed, then damaged areas can be properly repaired, but labor requirements and process complexity increase
Solution Approach 1:
The patent extracts only the damaged material from the repair cavity while leaving the surrounding sound material in place. The foamable media is then injected to fill and secure only the damaged area, eliminating the need for complex scarfing operations and extensive material removal that characterize traditional repair methods.
Solution Approach 2:
The repair process is segmented into discrete steps: cavity preparation, foamable media injection, and expansion/curing. This segmentation allows the repair to be performed independently of the surrounding structure, simplifying the overall process by isolating the repair zone from the need for extensive material removal and replacement operations.
3Productivity
If simple doubler patches are applied, then repair speed increases, but aesthetic and aerodynamic properties deteriorate due to protrusions
Solution Approach 1:
The foamable media allows for precise control of the repair volume and shape through parameter adjustment of the foam expansion. By controlling the expansion ratio and foam density, the repair can be formed to match the contours of the surrounding structure, eliminating protrusions and restoring surface smoothness while maintaining repair speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method simplifies and accelerates the repair process, reducing material removal and labor needs, while maintaining or restoring the structural integrity and aesthetics of composite structures, making it more efficient and cost-effective.
Implementation Method 1
foamable media is configured to expand according to a predetermined change in condition or triggering event
Implementation Method 2
the foaming agent comprises one or more of a physical foaming agent, a chemical foaming agent
Implementation Method 3
the foaming agent comprises one or more of a physical foaming agent, a chemical foaming agent
Implementation Method 4
the foamable media comprises a polymer matrix configured to hold a foaming agent
Implementation Method 5
expanding the foamable media placed in the repair cavity
Data Source
AI summary
A method for repairing a composite structure, includes creating a repair cavity in a composite structure, placing foamable media in the repair cavity, placing a replacement skin over the repair cavity, and expanding the foamable media placed in the repair cavity.