Woven preform, composite, and method of making thereof
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Solution Overview
Problem
Traditional composite window frames for aircraft face challenges in incorporating features like upstanding legs and joggles due to their oval shape, requiring labor-intensive darting that reduces strength and increases weight, while existing solutions lack continuous fiber reinforcement across interfaces.
Innovation Solution
A three-dimensional woven preform using warp-steered fabric with stretch broken carbon fibers and conventional carbon fibers, integrated to form upstanding legs and joggles without darts, ensuring continuous fiber reinforcement and reduced weight, fabricated using a differential take-up mechanism on a loom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If traditional composite window frames use conventional fabric or tape with darts to form curved shapes, then the frame can accommodate the oval shape of the fuselage, but the hand labor required increases and the strength of the resulting composite decreases
Solution Approach 1:
The fabric is divided into multiple plies or layers that can be independently positioned and oriented. Each ply can be cut and arranged to follow the contour of the oval fuselage section, eliminating the need for darts while maintaining continuous fiber reinforcement. This segmentation allows the fabric to conform to the curved shape without compromising structural integrity.
Solution Approach 2:
The invention transitions from two-dimensional fabric cutting and darting to a three-dimensional layered construction approach. By stacking multiple plies at different orientations and positions, the frame achieves the complex oval curvature without requiring fabric to be stretched or folded, thereby eliminating darts and maintaining continuous fiber paths for superior strength.
2Shape
If darts are used to form the curved shape of the window frame, then the oval shape can be achieved, but the fabrication labor increases and weak joints are created
Solution Approach 1:
The window frame construction is segmented into multiple discrete plies that can be pre-cut and pre-positioned before assembly. This segmentation eliminates the need for complex darting operations during fabrication, as each ply can be independently shaped and stacked to form the final curved geometry, significantly reducing hand labor requirements.
Solution Approach 2:
The plies are prepared in advance with predetermined cuts and orientations before assembly. This preliminary action allows the complex curved shape to be achieved through simple stacking and bonding operations rather than requiring labor-intensive darting and shaping during the main fabrication process.
3Shape
If darts are used to form complex features like upstanding legs, then the desired geometry can be achieved, but the strength of the resulting composite is reduced
Solution Approach 1:
The upstanding leg feature is formed by segmenting the fabric into multiple plies that are stacked and bonded together, rather than using a single piece of fabric with darts. This allows continuous fiber reinforcement to be maintained through the leg structure and its interface with the main frame body, eliminating weak joints while achieving the required geometry.
Solution Approach 2:
The invention uses a composite construction of multiple fabric plies with different orientations and positions to form the upstanding leg. This layered composite approach provides continuous fiber reinforcement through the interface between the leg and the main frame body, significantly improving the strength at this critical junction compared to traditional darted constructions.
4Strength
If continuous fiber reinforcement is implemented across interfaces, then the strength is improved, but the fabrication complexity increases
Solution Approach 1:
The fabric reinforcement is segmented into multiple plies that can be independently manufactured, positioned, and bonded. This segmentation simplifies the fabrication process by allowing each ply to be prepared separately with standard cutting and bonding equipment, while the cumulative effect of multiple plies achieves continuous fiber reinforcement across interfaces without requiring complex specialized machinery.
Data Source
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AI summary
A three dimensional woven preform, a fiber reinforced composite incorporating the preform, and methods of making thereof are disclosed. The woven preform includes one or more layers of a warp steered fabric. A portion of the warp steered fabric is compressed into a mold to form an upstanding leg (20). The preform includes the upstanding leg and a joggle (15) in a body portion. The body portion and upstanding leg are integrally woven so there is continuous fiber across the preform. A portion of the warp steered fabric includes stretch broken carbon fibers in the warp direction, and another portion includes conventional carbon fibers. The warp steered fabric can be woven on a loom equipped with a differential take-up mechanism. The warp steered fabric can be a single or multilayer fabric. The preform or the composite can be a portion of an aircraft window frame (10).