Aircraft Fuselage Door Frame Load Path Optimization
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Solution Overview
Problem
Conventional aircraft fuselage structures with a uniform grid of frame and stringer elements do not align with actual load paths, leading to suboptimal weight distribution, and their complex rearrangement for optimal weight is impractical with traditional manufacturing methods.
Innovation Solution
The support structure around the door opening is optimized by incorporating angled elements that follow the main load paths, forming triangular shapes which are more stable and lightweight, and can be manufactured integrally with the skin element using additive layer manufacturing (ALM) techniques, eliminating the need for separate parts and connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the support structure uses a uniform grid of frame and stringer elements extending in longitudinal and circumferential directions, then the manufacturing and mounting is simple and reliable, but the structure does not align with actual load paths leading to suboptimal weight distribution
Solution Approach 1:
The patent applies local quality by transitioning from a uniform grid structure to a non-uniform arrangement where support elements are strategically positioned along identified load paths. The support elements are distributed non-uniformly with higher density in regions of high stress concentration, allowing the structure to adapt locally to load requirements rather than using a homogeneous grid pattern throughout.
Solution Approach 2:
The patent implements parameter changes by modifying the orientation and distribution parameters of support elements based on load path analysis. The support elements are angled relative to the longitudinal and circumferential directions to match the skew angle of principal stress trajectories, transforming the structural parameters from a standard orthogonal grid to an optimized angled configuration.
2Weight of moving object
If the support structure is rearranged to align with main load paths forming triangular shapes, then the weight is minimized, but the manufacture and mounting becomes extremely complex and expensive with traditional methods
Solution Approach 1:
The patent applies merging by integrating the support structure with the skin element into a single monolithic component. This combination eliminates the need for separate support elements that would require complex assembly, joining, and alignment procedures. The integrated design allows the complex load-path-optimized geometry to be manufactured as one piece using additive layer manufacturing, thereby reducing assembly complexity while maintaining the optimized structural arrangement.
Solution Approach 2:
The patent substitutes traditional mechanical manufacturing and assembly methods with additive layer manufacturing technology. This manufacturing paradigm shift enables the production of complex triangular and angled support element configurations that would be extremely difficult or expensive to fabricate and assemble using conventional subtractive manufacturing and mechanical joining techniques.
3Ease of manufacture
If traditional manufacturing methods are used to create an optimized support structure along load paths, then the manufacturing process remains simple, but the structural optimization cannot be achieved
Solution Approach 1:
The patent implements parameter changes by modifying the orientation and distribution parameters of support elements based on load path analysis. The support elements are angled relative to the longitudinal and circumferential directions to match the skew angle of principal stress trajectories, transforming the structural parameters from a standard orthogonal grid to an optimized angled configuration.
Solution Approach 2:
The patent applies local quality by transitioning from a uniform grid structure to a non-uniform arrangement where support elements are strategically positioned along identified load paths. The support elements are distributed non-uniformly with higher density in regions of high stress concentration, allowing the structure to adapt locally to load requirements rather than using a homogeneous grid pattern throughout.
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 approach reduces the weight of the support structure while maintaining structural stability, simplifying manufacturing and mounting processes, and allows for more efficient load distribution along the aircraft fuselage.
Implementation Method 1
can be manufactured integrally with the skin element using additive layer manufacturing (ALM) techniques
Data Source
AI summary
An aircraft fuselage structure comprising a skin element having an inner surface, a support structure connected to the inner surface for supporting the skin element, and a door opening provided in the skin element, wherein the support structure comprises an upper longitudinal element, a lower longitudinal element, a first circumferential element and a second circumferential element provided at the door opening. The object to provide an aircraft fuselage structure, wherein the support structure around the door opening is optimized for a minimum weight, is achieved in that the support structure comprises a first upper angled element extending from an upper first corner to an upper center point, and a second upper angled element extending from an upper second corner to the upper center point, such that the upper longitudinal element, the first upper angled element, and the second upper angled element together form a central upper triangle.