Folded Fiber Prepreg for Lightweight Composite Materials
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Solution Overview
Problem
Existing fiber-reinforced composite materials face a trade-off between weight reduction and maintaining mechanical properties, as increasing porosity for weight reduction significantly deteriorates mechanical properties, and existing techniques either require specific molding dies or fail to control pore size and structure effectively.
Innovation Solution
A prepreg is developed with a reinforced fiber substrate folded at angles between 0° and 90°, which is then impregnated with resin, allowing for controlled expansion and pore formation during molding, thereby achieving both lightweight and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If porosity is increased for weight reduction, then lightweight properties are improved, but mechanical properties are dramatically deteriorated
Solution Approach 1:
The patent introduces a porous structure into the fiber-reinforced composite material by forming voids between folded fiber bundles. This porous structure reduces the overall density and weight of the material while the folded configuration maintains structural integrity. The pores are created through a specific folding process where fiber bundles are folded back on themselves, creating controlled void spaces that reduce weight without completely compromising mechanical strength.
Solution Approach 2:
The fiber bundles are divided into multiple segments through folding, creating a series of folded sections rather than continuous straight bundles. This segmentation allows the creation of a porous structure where voids exist between the folded segments. The segmented folded structure provides both weight reduction through porosity and maintains mechanical properties through the distributed fiber architecture that can still carry loads effectively.
2Strength
If a reinforcing structure such as rib or boss is adopted, then mechanical properties are improved, but specific molding die and thickness reduction are required
Solution Approach 1:
The reinforcing structure is created during the fiber bundle folding process itself, before the molding step. The fiber bundles are pre-folded into a specific configuration that creates both the porous structure and the reinforcing geometry. This preliminary folding action eliminates the need for additional molding dies or tools to create reinforcing features, as the structure is self-formed during preparation.
Solution Approach 2:
The fiber bundle folding process serves multiple functions simultaneously: it creates the porous structure for weight reduction, forms the reinforcing geometry for mechanical strength, and prepares the material for molding without requiring additional equipment. The folding process is self-sufficient, eliminating the need for separate reinforcing structure creation steps and complex molding dies.
3Weight of moving object
If zigzag-shaped structure is formed, then weight reduction is achieved, but the structure is easily opened by load in bending direction
Solution Approach 1:
The patent combines the folded fiber bundle structure with a resin matrix to create a composite material. The resin impregnates the folded fiber bundles and bonds them together, creating a composite structure that maintains the weight benefits of the folded configuration while providing the structural stability needed to resist opening under bending loads. The composite action of fiber plus resin solves the reliability issue.
Solution Approach 2:
The fold angle is controlled to be within a specific range (0° ≤ θ < 90°) to optimize the balance between weight reduction and structural stability. This parameter control ensures that the folded structure maintains sufficient rigidity to resist opening under load while still creating adequate porosity for weight reduction. The specific angle range prevents the structure from being too open while maintaining the folded configuration benefits.
Data Source
AI summary
An object of the present invention is to provide a fiber-reinforced composite material achieving both lightweight properties and mechanical properties, a laminate thereof, and a prepreg capable of easily molding a sandwich structure thereof. The present invention is a prepreg comprising a reinforced fiber substrate (B) impregnated with a resin (A), wherein the reinforced fiber substrate (B) exists in a folded state having a plurality of folds with a fold angle of 0° or more and less than 90° in the prepreg.