Composite Structure Crack Barrier Layer
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Solution Overview
Problem
Multi-layer laminate structures, such as those used in aircraft components, are susceptible to micro-cracks and delamination during service and manufacturing, making them difficult to detect and prone to damage propagation.
Innovation Solution
A composite structure with a multi-layer laminate folded to define a base, web, and folded tip region, incorporating a crack barrier layer to restrict crack propagation, and optionally a detection layer for impact damage visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If multi-layer laminate structures are used to reduce aircraft weight, then fuel efficiency is improved, but the structure becomes susceptible to micro-cracks and delamination
Solution Approach 1:
The patent applies composite materials by integrating a crack barrier layer made of discontinuous fibers (glass, carbon, or aramid) within the multi-layer laminate structure. This crack barrier layer is positioned between the outer surface and the folded tip region, creating a composite structure that combines the weight benefits of CFRP with the damage resistance of discontinuous fiber barriers, thereby resolving the contradiction between weight reduction and reliability enhancement
2Shape
If the multi-layer laminate is folded to create the stringer structure, then structural shape is achieved, but crack propagation is facilitated in the folded tip region
Solution Approach 1:
The patent applies local quality by positioning the crack barrier layer specifically in the folded tip region where cracks are most likely to initiate and propagate. The discontinuous fibers in this localized area are oriented to intercept cracks traveling parallel to the laminate layers, providing targeted protection exactly where the folded geometry creates vulnerability, thus resolving the contradiction between achieving the required stringer shape and preventing crack propagation
3Device complexity
If traditional multi-layer laminate structures are used, then manufacturing complexity is reduced, but damage detection becomes difficult
Solution Approach 1:
The patent applies the color changes principle by using detection layers with different optical properties than the surrounding laminate. These detection layers can be visualized through optical methods such as thermography or ultrasonic testing, allowing damage to be detected through changes in how the structure interacts with energy fields. This enables damage detection without significantly increasing manufacturing complexity, as the detection layers are integrated into the existing laminate fabrication process
Data Source
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AI summary
A composite structure that includes a multi-layer laminate including a plurality of layers of material, and at least one crack barrier layer extending within the plurality of layers of material. The multi-layer laminate is folded to define a first web region and a second web region in a face-to-face relationship, and a folded tip region defined between the first web region and the second web region. The at least one crack barrier layer is configured to restrict crack propagation from spreading through the plurality of layers of material in the folded tip region.