Aircraft Fuselage Frames with Closed Section Stringers
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Solution Overview
Problem
The aeronautical industry faces challenges in creating lightweight yet highly stiff and resistant aircraft fuselage structures, particularly in manufacturing composite materials with closed section frames, which are stronger but more complex to produce compared to open section frames.
Innovation Solution
A fuselage structure combining open section S-shaped frames with closed section stringers, featuring a hat, webs, and feet joined to the skin, with specific angular configurations and connections that simplify manufacturing and enhance resistance, using composite materials to reduce weight and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If closed section frames are used to increase strength, then resistance and buckling strength are improved, but manufacturing complexity increases
Solution Approach 1:
The closed section frame is divided into two separate components: an open section frame and a closed section stringer. The open section frame provides basic structural support and is easier to manufacture, while the closed section stringer reinforces specific areas to achieve the required strength. This segmentation allows each component to be optimized independently for its specific function.
Solution Approach 2:
The invention combines the open section frame and closed section stringer into an integrated structure where the stringer is positioned along the frame and connected at specific points. This merging creates a composite structure that achieves the strength benefits of closed section frames while maintaining the manufacturing simplicity of open section frames.
2Stability of the object's composition
If closed section frames are used to increase buckling strength, then structural stability is improved, but manufacturing difficulty increases
Solution Approach 1:
Instead of making the entire frame a closed section, the closed section stringer is placed only in specific locations where buckling resistance is most needed. This local application of closed section geometry provides enhanced stability where required while keeping the majority of the structure as simple open sections for ease of manufacture.
Solution Approach 2:
The frame structure is segmented into regions with different structural characteristics: open section frame members for general support and closed section stringers for localized buckling resistance. This segmentation allows the structure to achieve high stability where needed without the manufacturing complexity of fully closed section frames.
3Weight of moving object
If composite materials are used to reduce weight, then weight is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The composite structure is divided into modular components (frames and stringers) that can be manufactured separately with standardized precision requirements. This segmentation allows for easier quality control and assembly compared to manufacturing large monolithic composite structures, reducing the overall manufacturing precision burden while still achieving weight reduction benefits.
Data Source
AI summary
A fuselage section of an aircraft includes a skin, a plurality of frames positioned transversely to a longitudinal axis of a fuselage of the aircraft, and a plurality of longitudinal stringers at least one of which is configured with a closed transversal section including a stringer hat, two stringer webs, and two stringer feet joined to the skin. At least one of the frames is configured in at least one sector with a frame foot joined to the skin, a frame web having holes at crossing zones with the stringers, a frame cap, and a frame cap extension which does not interfere with the stringers. The frames are joined to, at least, the stringer hats at crossing zones of the frames and the stringer hats.