Monofilament String with Graphene Sheath for Racket

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Solution Overview

Problem

Monofilament strings for racket sports face challenges in achieving a balance between power, control, comfort, and durability, with existing solutions either compromising on power for durability or vice versa, and requiring high physical strength for effective ball acceleration and control.

Innovation Solution

A monofilament string design featuring a core made of polyamide with a sheath containing graphene or graphane nanoparticles, allowing for enhanced durability and maintaining power and control properties through a co-extrusion process, where the nanoparticles improve tensile strength and temperature resistance without excessive rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an intermediate reinforcing layer made of composite material is added to increase durability, then durability is improved, but power properties are reduced due to reduced ability to bend at impact

Engineering Contradiction:
ImprovedurabilityVSAvoidpower properties
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent uses a composite material consisting of polyamide and graphene or graphane nanoparticles. The graphene or graphane nanoparticles (0.1-5% by weight) reinforce the polyamide matrix, providing enhanced durability and tensile strength while maintaining the material's flexibility and elasticity, thus resolving the contradiction between durability and power properties

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies the composite material specifically in the sheath layer surrounding the core, rather than throughout the entire string structure. This localized application provides durability enhancement at the surface where wear occurs, while the core maintains its elasticity and bending ability for power properties

Inventive Principle:
Principle #3Local quality

2Strength

If carbon nanotubes are added as an additive in wear-resistant coating, then wear resistance is improved, but the material becomes substantially rigidified and difficult to process

Engineering Contradiction:
Improvewear resistanceVSAvoidprocessability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the type of nanoparticle from carbon nanotubes to graphene or graphane nanoparticles, and optimizes the concentration to 0.1-5% by weight. This parameter change provides wear resistance while maintaining processability, as the planar structure of graphene and graphane at these concentrations does not substantially rigidify the polyamide matrix like carbon nanotubes would

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If monofilament strings are made of polyethylene or polyester to achieve high stiffness and good control, then control is improved, but high physical strength is needed to accelerate the ball

Engineering Contradiction:
ImprovecontrolVSAvoidphysical strength required
Core Design Contradiction:
Measurement precisionVSForce

Solution Approach 1:

The patent creates a composite material of polyamide with graphene or graphane nanoparticles that achieves high stiffness for control while maintaining sufficient elasticity for power. The nanocomposite structure provides enhanced mechanical properties that allow the string to be stiff for control yet responsive for ball acceleration without requiring high physical strength

Inventive Principle:
Principle #40Composite materials

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 string achieves improved durability and stability over time, maintaining mechanical properties and reducing tension loss, while allowing for efficient ball acceleration and control without high physical strength, and providing comfort by minimizing vibrations and friction.

Implementation Method 1

the sheath is made of a second material comprising at least a polyamide, wherein the second material is a polyamide matrix comprising graphene or graphane nanoparticles with a concentration ranging from 0.1% to 5% in weight

Methodology Applied
Scientific EffectNanocomposite reinforcement: Composite Materials

Implementation Method 2

the sheath is made of a second material comprising at least a polyamide, wherein the second material is a polyamide matrix comprising graphene or graphane nanoparticles

Methodology Applied
Scientific EffectGraphene: Graphene

Implementation Method 3

allowing for enhanced durability and maintaining power and control properties through a co-extrusion process

Methodology Applied
Scientific EffectCo-extrusion: Extrusion

Implementation Method 4

providing comfort by minimizing vibrations and friction

Methodology Applied
Scientific EffectVibration damping: Damping

Data Source

PatentEP3997261B1Monofilament string for a racket
Publication Date: 2023.08.30 SPEED FRANCE SAS
  • EP3997261B1 patent drawingFigure 1~2
  • EP3997261B1 patent drawingFigure 3~4
  • EP3997261B1 patent drawingFigure 5~6

AI summary

The present invention relates to a monofilament string (1) for a racket (5), comprising a core (2) consisting of a single filament and a sheath (3) extending around the core (2) and in contact with the core (2), wherein: - the core (2) is made of a first material comprising at least a polyamide, - the sheath (3) is made of a second material comprising at least a polyamide, wherein the second material comprises graphene or graphane nanoparticles with a concentration ranging from 0.1% to 5% in weight, preferably from 0.1% to 2% in weight, and more preferably from 0.1% to 1% in weight of the weight of the sheath.