Hollow Fiber with Gradient Properties for Composite Reinforcement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional composite materials used in aircraft and other structures face challenges with impact resistance and fracture toughness due to mismatched fiber-matrix interface properties, and the addition of nanostructures like carbon nanotubes increases resin viscosity, making processability difficult and weight reduction desirable.
Innovation Solution
A hollow fiber with a core-shell structure is developed, where nanostructures such as carbon nanotubes act as orientation templates for polymers within the inner core, enhancing tensile modulus and strength, and a fugitive polymer is used to create a hollow precursor fiber that is oxidized to improve resistance to microfracture formation at the fiber-matrix interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon nanotubes are added to liquid resin to enhance impact resistance and fracture toughness, then the structural properties of composite materials are improved, but the resin viscosity dramatically increases, decreasing processability
Solution Approach 1:
The patent extracts carbon nanotubes from the liquid resin mixture and places them directly into the fiber core during the fiber formation process. This separation allows the nanotubes to be positioned where they are needed for structural reinforcement without remaining in the liquid resin that requires processing, thereby maintaining resin processability while achieving enhanced impact resistance and fracture toughness in the final composite material.
Solution Approach 2:
The patent performs preliminary action by incorporating carbon nanotubes into the fiber core structure before the resin is applied and cured. The nanotubes are pre-positioned and aligned within the fiber during manufacturing, creating a prepared reinforcement framework that will enhance impact resistance and fracture toughness without requiring the nanotubes to be mixed into the liquid resin at the time of composite fabrication.
2Strength
If high modulus and strength carbon fibers are used to increase fiber performance, then tensile strength is improved, but the fiber-matrix interface properties decrease due to stiffness mismatch
Solution Approach 1:
The patent applies local quality by creating a functionally graded fiber structure where the core region containing carbon nanotubes has different mechanical properties than the outer fiber regions. The nanotube-reinforced core provides enhanced tensile strength and stiffness, while the gradient transition to the outer regions creates a more gradual stiffness profile that reduces the mismatch with the matrix material, thereby improving fiber-matrix interface properties and overall reliability.
3Ease of manufacture
If conventional fiber plies are laminated with uncured matrix material and cured to form composite parts, then composite structures are created, but weight reduction opportunities are limited
Solution Approach 1:
The patent utilizes composite materials by integrating carbon nanotubes within the fiber core structure to create a hybrid reinforcement system. The combination of conventional carbon fibers with nanotube reinforcement achieves enhanced mechanical properties including improved tensile strength and impact resistance, allowing for weight reduction in composite structures while maintaining or improving performance characteristics.
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 hollow fiber exhibits improved resistance to microfracture formation and weight reduction while maintaining mechanical properties, addressing the limitations of conventional composite materials by optimizing fiber-matrix interface and processability.
Implementation Method 1
The plurality of carbon nanotubes act as an orientation template for orientation of the plurality of first polymers in a direction parallel to a longitudinal axis of the hollow fiber
Implementation Method 2
heating the hollow precursor fiber to oxidize the hollow precursor fiber and to change a molecular-bond structure of the hollow precursor fiber
Data Source
AI summary
There is provided a method of making a hollow fiber. The method includes mixing, in a first solvent, a plurality of nanostructures, one or more first polymers, and a fugitive polymer which is dissociable from the nanostructures and the one or more first polymers, to form an inner-volume portion mixture. The method further includes mixing, in a second solvent, one or more second polymers to form an outer-volume portion mixture, and spinning the inner-volume portion mixture and the outer-volume portion mixture to form a precursor fiber. The method further includes heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber, and during heating, extracting the fugitive polymer from the inner-volume portion mixture. The method further includes obtaining the hollow fiber with the inner-volume portion having the nanostructures and the first polymers, and with the outer-volume portion having the second polymers.