Sandwich panel, method for producing unidirectional prepreg, and method for producing sandwich panel
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Solution Overview
Problem
Honeycomb sandwich panels with unidirectional fiber-reinforced resin skin layers face challenges due to the high cost and brittle fracture nature of carbon fibers, leading to undesirable cracking during machine processing and a need for a more cost-effective and ductile fracture mode.
Innovation Solution
A sandwich panel design incorporating unidirectional-fiber-reinforced resin bodies with alternating carbon and glass fiber bundles, where the nap of the fibers commingles or alternates, reducing resin content and enhancing adhesion, and using a phenol or epoxy resin matrix for improved heat resistance and fracture toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon fiber bundles are used in the unidirectional-fiber-reinforced resin body, then the weight of the sandwich panel is reduced and rigidity is increased, but the cost increases significantly and the fracture mode becomes brittle
Solution Approach 1:
The patent applies composite materials by combining carbon fiber bundles and glass fiber bundles in the unidirectional-fiber-reinforced resin body. This allows the structure to benefit from the high rigidity of carbon fiber while incorporating the cost-effectiveness and ductile fracture characteristics of glass fiber, resolving the contradiction between strength/rigidity and manufacturing cost.
2Weight of moving object
If carbon fiber bundles are used in the unidirectional-fiber-reinforced resin body, then the weight of the sandwich panel is reduced, but the fracture mode becomes brittle with all-at-once fracture
Solution Approach 1:
The patent combines carbon fiber bundles (providing lightweight properties) with glass fiber bundles (providing ductile fracture characteristics). The glass fiber component enables gradual fracture propagation rather than sudden failure, while the carbon fiber maintains the lightweight advantage, thus resolving the contradiction between weight reduction and reliable fracture mode.
3Weight of moving object
If a unidirectional-fiber-reinforced resin body comprising carbon fiber bundles is used in the skin layer, then the weight is reduced, but tiny cracks readily form during machine processing
Solution Approach 1:
The patent uses a composite of carbon fiber bundles and glass fiber bundles in the unidirectional arrangement. The glass fiber component provides crack resistance and toughness, preventing the formation of tiny cracks during machine processing while maintaining the lightweight properties contributed by the carbon fiber, thus resolving the contradiction between weight reduction and resistance to processing-induced cracking.
Data Source
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AI summary
Provided is a sandwich panel which not only is lightweight but also can be produced inexpensively, which moreover has a fracture mode in which the sandwich panel fractures gradually near the fracture point rather than fracturing all at once, and furthermore in which it is possible to mitigate cracking that occurs in the direction of fibers in a unidirectional fiber body during machine processing. A sandwich panel in which a skin layer (2) is provided to upper and lower surfaces of a core (1), wherein the sandwich panel is characterized in that: the skin layer (2) is obtained by layering unidirectional-fiber-reinforced resin bodies (3, 4) that comprise a matrix resin and a unidirectional fiber body in which carbon fiber bundles (A) and glass fiber bundles (B) are aligned, and woven-fiber-reinforced resin bodies (5, 6) that comprise a matrix resin and an interwoven fiber body; and commingled parts (C) in which the nap of the carbon fiber bundles (A) and that of the glass fiber bundles (B) commingle, or unitary parts where only the nap of the carbon fiber bundles (A) is present, are provided along the length direction of each fiber bundle between adjacent carbon fiber bundles (A) and glass fiber bundles (B) in the unidirectional-fiber-reinforced resin bodies (3, 4).