Low Aspect Ratio Nanostructures for High Strain Composites

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Solution Overview

Problem

Ceramic matrix composites (CMCs) face limitations in mechanical properties due to low matrix-to-fiber adhesion, leading to reduced fracture toughness and inter-laminar properties, and existing composite materials with nanostructures often suffer from processing challenges like entanglement and clumping, limiting high nanostructure loading and effective load transfer.

Innovation Solution

A composite material with a matrix comprising hollow nanostructures of low aspect ratio (3 to 10) and a binder material forming an interconnected microstructure, allowing for enhanced mechanical strain and load transfer without entanglement, and a method involving the use of aligned or randomly oriented nanostructures to create a high free volume, lightweight matrix that promotes strain capability and toughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If long fibers are mixed with cup-type carbon nanotubes to produce a composite material, then the composite material achieves improved mechanical properties, but the nanostructures become entangled and clumped during processing

Engineering Contradiction:
Improvemechanical propertiesVSAvoidprocessing
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the aspect ratio parameter of nanostructures from high (conventional) to low (3-10), transforming their geometry from elongated to more equiaxial shapes. This parameter change prevents entanglement and clumping during processing while maintaining mechanical reinforcement capabilities, resolving the contradiction between improved strength and ease of manufacture.

Inventive Principle:
Principle #35Parameter changes

2Strength

If matrix-to-fiber adhesion is reduced to increase fracture toughness in CMC materials, then crack propagation is interrupted, but inter-laminar properties and mechanical strength are severely degraded

Engineering Contradiction:
Improvefracture toughnessVSAvoidinter-laminar properties
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies local quality by using low aspect ratio nanostructures that create localized stress distribution patterns different from conventional high aspect ratio fibers. The unique geometry enables crack interruption and toughness improvement at the micro-scale while maintaining adequate inter-laminar bonding, resolving the contradiction between fracture toughness and inter-laminar properties.

Inventive Principle:
Principle #3Local quality

3Strength

If high nanostructure loading is used to enhance mechanical properties, then the composite achieves higher strength, but the nanostructures become entangled and clumped during processing

Engineering Contradiction:
Improvemechanical propertiesVSAvoidmicrostructure
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent changes the aspect ratio parameter of nanostructures to low values (3-10), which fundamentally alters their packing and flow characteristics. This parameter change enables high nanostructure loading without entanglement or clumping, achieving enhanced mechanical properties while maintaining a simple, processable microstructure.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2612837B1Structural composite materials with high strain capability
Publication Date: 2019.06.19 LOCKHEED MARTIN CORP
  • EP2612837B1 patent drawingFigure 1~3
  • EP2612837B1 patent drawingFigure 4A~7
  • EP2612837B1 patent drawingFigure 8

AI summary

Composite materials are provided that include nanostructures bound together by a binder material in a manner that provides the composite material with high strain capability and toughness. The nanostructures and binder material form a matrix material in which long fiber reinforcements may be embedded to form a structural composite material. The nanostructures may have relatively low aspect ratios by having relatively large diameters and/or relatively small lengths. These low aspect ratio nanostructures do not become entangled during processing or in the finished matrix material, and can be arranged in an interconnected network to form a skeletal structure for the matrix material. The skeletal structure is highly flexible due to very high free volume within the matrix material and the ability of nanostructures to flex and return to their original shapes. As applied to ceramic matrix composite (CMC) materials, this tougher, more flexible matrix material allows for full bonding of the matrix material with the fiber reinforcements so that CMC materials can realize the full potential of the reinforcing fibers and possess superior inter-laminar strength.