3D Woven Preform for Aircraft Window Frame
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Solution Overview
Problem
Traditional composite window frames in aircrafts face challenges in incorporating upstanding legs and joggles due to their oval shape, leading to non-uniform strength and stiffness, and require parasitic barrier plies to prevent corrosion, increasing production cost and weight.
Innovation Solution
A three-dimensional woven preform using warp-steered fabrics with darted and un-darted portions, where the warp fibers are continuous in circumferential and radial directions, allowing for uniform strength and stiffness alignment with the window frame's principal directions, and incorporating stretch broken or conventional carbon fibers, woven on a loom with a differential take-up mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional metallic window frames are used in composite fuselages, then corrosion protection is provided, but the weight increases and production cost increases due to parasitic barrier plies
Solution Approach 1:
The patent removes the parasitic barrier plies from the window frame structure by making the frame itself corrosion-resistant through composite material selection and design. The corrosion protection function is extracted from a separate metallic layer and integrated into the composite structure, eliminating the need for additional barrier plies and reducing overall weight
Solution Approach 2:
The patent employs composite materials for the window frame construction, combining fiber reinforcement with matrix materials to create a structure that is both strong and corrosion-resistant. This composite approach replaces traditional metallic frames that required separate corrosion protection layers, achieving both weight reduction and corrosion resistance simultaneously
2Shape
If darts are used to form curved shape of oval window frame, then the frame shape is achieved, but the strength and stiffness are degraded
Solution Approach 1:
The patent incorporates reinforcement features directly into the preform construction before composite formation. The reinforcement plies are strategically positioned in advance to counteract the stress concentrations that would normally occur at dart locations, preventing strength degradation while maintaining the curved oval shape
Solution Approach 2:
The patent applies localized reinforcement at specific critical areas of the window frame, particularly at corners and curved sections where darts are located. By concentrating reinforcement materials where needed rather than uniformly throughout, the structure maintains strength and stiffness at critical locations while achieving the desired oval shape
3Stability of the object's composition
If quasi-isotropic layup is used to achieve uniform stiffness, then stiffness uniformity is improved, but the fiber orientation does not align with principal window frame directions
Solution Approach 1:
The patent employs different fiber orientation strategies in different regions of the window frame. In areas where uniform stiffness is critical, quasi-isotropic layup is used, while in regions where strength in principal directions is paramount, unidirectional or biased ply orientations aligned with the frame's principal stress directions are implemented, optimizing both stiffness and strength locally
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 two or more warp steered fabrics. The warp steered fabrics include a darted portion and an un-darted portion. The darted portions of the warp steered fabrics are joined to un-darted portions of one another so as to provide continuous fiber in the circumferential and radial directions of all portions of the preform. An un-darted portion in one steered fabric reinforces a darted portion in the other. The warp steered fabrics can be woven on a loom equipped with a differential take-up mechanism. The warp steered fabrics can be single or multilayer fabrics. The final preform can be a portion of an aircraft window frame.