Braided Composite Winglet Spar Design
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Solution Overview
Problem
The existing methods for manufacturing aircraft winglets using composite materials face challenges in tailoring structural behavior, particularly at the attachment point, due to difficulties in accessing complex geometries and the need for over-engineering, which increases cost and weight, and results in inefficient load transfer and joint technology between the wing tip device and the wing.
Innovation Solution
A winglet design featuring a tubular main spar with a tapered portion and C-shaped front spar, where the upper and lower front spar caps extend forward to allow direct attachment of the leading edge skin without joggles, and a braided composite spar with varying fibre angles and pitches to optimize structural properties, enabling efficient load transfer and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used to manufacture composite winglet spars, then the structural behavior cannot be adequately tailored, but using innovative braiding processes increases manufacturing complexity
Solution Approach 1:
The patent applies parameter changes by varying the braid angle, fibre pitch, and areal weight along the length of the spar. This allows the structural behavior to be tailored precisely - with higher bending stiffness at the tip and appropriate load transfer characteristics at the attachment point - while using a continuous braiding process that manages manufacturing complexity through automated parameter control
Solution Approach 2:
The patent implements local quality by creating spatially varying fibre orientations and thicknesses within the composite spar. The braid angle and areal weight are optimized for different locations: steeper angles and higher areal weights at the attachment point for load transfer, and tailored angles at the tip for bending stiffness, with each section having properties optimized for its specific functional requirements
2Reliability
If over-engineering is applied at the attachment point to guarantee mechanical properties, then structural integrity is improved, but weight and cost increase
Solution Approach 1:
The patent uses parameter changes to achieve the required mechanical properties without over-engineering. By precisely controlling the braid angle and areal weight distribution, the attachment point achieves adequate load transfer capacity with optimized fibre orientation, while the tip achieves required bending stiffness with reduced material where possible, avoiding unnecessary weight
Solution Approach 2:
The patent applies local quality by providing enhanced structural properties specifically where needed - higher areal weight and optimized fibre angles at the attachment point for load transfer, and tailored properties at the tip for bending stiffness - rather than uniformly over-engineering the entire spar, thus minimizing unnecessary weight
3Productivity
If complex spar geometry is used to enable winglet attachment, then load transfer efficiency is improved, but manufacturing difficulty increases due to lack of access for tooling and assembly
Solution Approach 1:
The patent replaces complex mechanical assembly operations with a continuous automated braiding process. The complex tapered geometry with varying braid angles is created directly by the braiding machine following digital specifications, eliminating the need for manual tooling access and multi-step assembly operations while achieving the required load transfer efficiency
Solution Approach 2:
The patent applies preliminary action by pre-programming the braiding machine with the exact geometry specifications before manufacturing. The complex tapered shape and fibre orientation patterns are predetermined and executed automatically, eliminating the need for on-site adjustments, tooling access, and assembly operations that would be required with conventional manufacturing
Data Source
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AI summary
A winglet (5) comprising a tubular main spar (10) with forward and aft main spar webs (12, 13) joined by upper and lower main spar caps (14, 15); a front spar (11) with a front spar web (16), an upper front spar cap (17), and a lower front spar cap (18); an upper skin (19) joined to the upper main spar cap (14) and the upper front spar cap (17); and a lower skin (20) joined to the lower main spar cap (15) and the lower front spar cap (18). The winglet (5) is manufactured by co- curing the upper skin (19) to the upper main spar cap (14) and the upper front spar cap (17); and co-curing the lower skin (20) to the lower main spar cap (15) and the lower front spar cap (18).