CFRP Layer Structure for Edge Glow Suppression
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Solution Overview
Problem
Carbon fiber-reinforced composites (CFRP) exhibit high risk of edge glow due to complex electrical characteristics, particularly when subjected to lightning strikes, and existing methods to enhance electroconductivity are either insufficient or costly.
Innovation Solution
A carbon-fiber-reinforced composite material with specific layer structures, including high-Vcf and low-Vcf sublayers, and controlled resin thickness between layers, to enhance electroconductivity without excessive use of conductive particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroconductive particles are added between CF sheets to enhance electroconductivity, then edge glow is inhibited, but cost increases and the amount of particles required is excessive
Solution Approach 1:
The patent applies local quality by creating sublayers with different carbon fiber volume content factors (Vcf) within specific layers. The structure includes high-Vcf sublayers (with Vcf ratio ≥0.5) positioned at the interfaces between layers having different fiber orientations, and low-Vcf sublayers (with Vcf ratio <0.5) positioned at the centers of these layers. This localized variation in Vcf provides enhanced electroconductivity precisely where needed (at layer interfaces) without requiring excessive electroconductive particles throughout the entire structure.
Solution Approach 2:
The patent utilizes parameter changes by controlling the carbon fiber volume content factor (Vcf) as a key parameter to enhance electroconductivity. By varying the Vcf within specific ranges in different sublayers, the material achieves improved lightning resistance through the inherent electrical properties of the carbon fiber structure rather than relying heavily on additional electroconductive additives.
2Reliability
If a lightning-resistant system with metal mesh or sealant is attached to CFRP, then safety against lightning is secured, but weight and cost increase
Solution Approach 1:
The patent applies self-service by enabling the CFRP structure itself to provide lightning protection through its inherent electroconductivity. The specific layer structure with controlled Vcf variations creates natural electroconductive pathways within the composite material, allowing it to dissipate lightning current without requiring external metal meshes or sealant systems. This integrates the lightning protection function directly into the structural material.
Solution Approach 2:
The patent merges the structural function and lightning protection function into a single integrated CFRP structure. By designing the layer structure with specific Vcf distributions, the same carbon fiber-reinforced composite material simultaneously provides mechanical strength and electrical conductivity for lightning protection, eliminating the need for separate protection systems.
3Adaptability or versatility
If CF sheets with different fiber orientations are laminated to achieve complicated shapes, then shape flexibility is improved, but electroconductivity becomes complicated and edge glow risk increases
Solution Approach 1:
The patent addresses this contradiction by applying local quality through sublayer differentiation. Within each layer of CF sheets with different fiber orientations, the structure is divided into sublayers with different Vcf values. The high-Vcf sublayers are positioned at the interfaces between differently oriented layers, providing enhanced electroconductivity at these critical interfaces where current transitions between layers occur, while low-Vcf sublayers are positioned at layer centers. This localized approach maintains shape flexibility through multidirectional lamination while managing electroconductivity uniformity through strategic Vcf distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed CFRP structure effectively inhibits edge glow and reduces the risk of lightning damage, while allowing for efficient induction welding and improved electrical conductivity.
Implementation Method 1
CF is an electrical conductor, and a matrix resin is generally an insulator in many cases. Because CF itself provides an electroconductive path, a CFRP has relatively high electroconductivity in the fiber-axis direction
Implementation Method 2
a resin portion between the specific Layer and at least one Layer adjacent to the specific Layer
Data Source
AI summary
[Problem] A problem to be addressed by the present invention is to provide a CFRP with a low risk of edge glow by virtue of controlling the structure of the CFRP and without relying on expensive electroconductive particles. In other words, provided is a CFRP such that the risk of edge glow is greatly decreased, even in a case where electroconductive particles are used in an amount equal to or smaller than in a conventional technology. Further provided is a CFRP such that the risk of edge glow is greatly decreased without using electroconductive particles.[Solution] A carbon-fiber-reinforced composite material including carbon fiber sheets containing unidirectionally arranged carbon fibers, laminated multidirectionally one on another, and impregnated with a matrix resin, which is cured; wherein, assuming that a region in which the carbon fibers have the same angle of fiber orientation consecutively in the thickness direction is defined as a Layer, and that, when the Layer is composed of a plurality of regions having a given thickness, and having different carbon fiber volume content factors (Vcf), each of the regions having a given thickness is defined as a Sublayer, the carbon fiber sheet contains a specific Layer that satisfies (1) to (3), and the thickness of a resin portion between the specific Layer and at least one Layer adjacent to the specific Layer is 5 μm or less; (1) the average Vcf of the Layer (hereinafter referred to as the Layer average Vcf) is 50% or more, (2) as both outermost parts of the Layer, Sublayers each having a Vcf the ratio of which to the Layer average Vcf is 0.5 or more (hereinafter, such a Sublayer is referred to as a high-Vcf Sublayer) are disposed, wherein each average Vcf is higher than the Layer average Vcf, and (3) between the high-Vcf Sublayers as both outermost parts of the Layer, a Sublayer having a Vcf the ratio of which to the Layer average Vcf is less than 0.5 (hereinafter, such a Sublayer is referred to as a low-Vcf Sublayer) exists.