Methods for manufacturing fiber-modified interlayers for composite structures
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Solution Overview
Problem
Composite structures toughened with thermoplastic particles or interlayers face issues with charging during lightning strikes, leading to edge glow, and exhibit lower mechanical-property retention at elevated temperatures.
Innovation Solution
A fiber-modified interlayer comprising a nonwoven fabric layer of continuous fibers with discontinuous fibers attached, which is integrated into a reinforcing fabric in an alternating configuration, along with a matrix material, to enhance impact resistance and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoplastic particles or interlayers are added to enhance impact resistance, then the impact resistance of the composite structure is improved, but the structure becomes subject to charging during lightning strikes leading to edge glow
Solution Approach 1:
The patent applies composite materials by combining thermoplastic interlayer with discontinuous conductive fibers (such as carbon fibers) to create a hybrid interlayer system. This composite interlayer simultaneously provides impact resistance from the thermoplastic matrix and electrical conductivity from the conductive fibers, thereby preventing charging during lightning strikes while maintaining enhanced impact resistance. The conductive fibers are dispersed throughout the thermoplastic interlayer to establish electrical pathways.
Solution Approach 2:
The patent applies local quality by adding conductive fibers specifically within the interlayer regions where impact resistance enhancement is needed, rather than throughout the entire composite structure. This localized modification provides electrical conductivity precisely where the thermoplastic interlayer is present, preventing edge glow at vulnerable locations while maintaining the overall structural integrity and impact resistance properties.
2Strength
If thermoplastic particles or interlayers are added to enhance impact resistance, then the impact resistance of the composite structure is improved, but the mechanical-property retention at elevated temperatures decreases
Solution Approach 1:
The patent applies composite materials by integrating discontinuous conductive fibers into the thermoplastic interlayer matrix. This composite structure allows the thermoplastic to provide impact resistance while the conductive fibers contribute to high-temperature stability and maintain mechanical properties. The synergistic combination enables the interlayer to withstand both impact loads and elevated temperatures more effectively than thermoplastic alone.
3Reliability
If a nonwoven fabric layer with discontinuous fibers is manufactured using the disclosed method, then the fiber-modified interlayer achieves improved impact resistance and electrical conductivity, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the interlayer manufacturing into distinct stages: first forming a nonwoven fabric layer from continuous fibers, then separately introducing discontinuous conductive fibers through a slurry application process. This segmented approach allows each component to be optimized independently and simplifies the overall manufacturing process compared to attempting to create a homogeneous composite fiber mat in a single step.
Solution Approach 2:
The patent applies the intermediary principle by using a slurry (liquid carrier medium) as an intermediary to introduce discontinuous conductive fibers onto the nonwoven fabric layer. The slurry acts as a carrier that facilitates uniform distribution of the conductive fibers and enables controlled application, thereby simplifying the manufacturing process while achieving the desired electrical conductivity and fiber distribution.
Data Source
AI summary
A composite manufacturing method includes the step of drawing a nonwoven fabric formed of continuous fibers through a slurry of discontinuous fibers suspended in a dispersive liquid to yield a fiber-modified interlayer comprising a network of said discontinuous fibers attached to said nonwoven fabric.