Resonant Frequency Shift for Non-Invasive Tire Thickness Measurement

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Solution Overview

Problem

Existing non-invasive thickness measurement techniques for materials, such as those using electromagnetic waves, are not universally applicable due to requirements for metallic substrates, homogeneous coatings, and physical access, limiting their suitability for various applications like tire thickness measurement.

Innovation Solution

A method involving the transmission of an oscillating signal through a tire using two electrically isolated pads, with varying frequencies to determine the resonant frequency shift caused by changes in tire thickness, allowing for non-invasive thickness measurement regardless of the tire's material homogeneity or presence of metal reinforcement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a cavity resonator is placed against a coated metallic surface to measure coating thickness, then the thickness measurement can be obtained, but the method requires the presence of a metallic substrate and physical access to the exposed surface, which limits applicability to other situations like tire thickness measurement

Engineering Contradiction:
Improvecoating thickness measurementVSAvoidapplicability to different materials and situations
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by developing a thickness measurement method that works for both metallic and non-metallic substrates. The electromagnetic wave-based resonant frequency measurement technique is adapted to measure tire thickness without requiring metal reinforcement, making the measurement system universally applicable to different tire constructions (radial, diagonal, steel-belted, etc.) and different materials (rubber compounds, treads, sidewalls).

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces the mechanical contact method (placing a cavity resonator physically against the surface) with an electromagnetic field-based method. Instead of requiring physical access and direct contact with the exposed surface, the system uses electromagnetic waves that can penetrate and interact with the tire material from a distance, substituting mechanical interaction with electromagnetic interaction to enable measurement in previously inaccessible situations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If physical or optical measurement methods are used to measure material thickness, then accurate measurements can be obtained, but the material must be cut or punctured, causing damage to the material

Engineering Contradiction:
Improvethickness measurement accuracyVSAvoidmaterial damage
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical cutting or puncturing methods with an electromagnetic field-based measurement system. The oscillating electromagnetic signal interacts with the tire material's dielectric properties without physically contacting or damaging it, enabling non-invasive thickness measurement while maintaining measurement precision through resonant frequency analysis.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an electromagnetic field as an intermediary between the measurement device and the tire material. Instead of direct mechanical contact that causes damage, the electromagnetic wave serves as a mediator that carries measurement information about thickness through the material's dielectric response, allowing accurate measurement without harmful physical interaction.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If traditional thickness measurement methods are used, then measurements can be obtained for specific materials, but the methods are not suitable for heterogeneous materials or materials with metal reinforcement like tires

Engineering Contradiction:
Improvethickness measurementVSAvoidsuitability for heterogeneous and metal-reinforced materials
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by utilizing the dielectric properties of the tire material as the measurement basis. Instead of relying on geometric or mechanical parameters that fail for heterogeneous materials, the system measures changes in electromagnetic parameters (resonant frequency, dielectric constant) that are characteristic of the material composition and thickness, enabling accurate measurement of heterogeneous and metal-reinforced tire structures.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent enhances universality by creating a measurement system that adapts to different tire constructions and materials. The electromagnetic resonance method works regardless of whether the tire is radial or diagonal, steel-belted or not, and can handle heterogeneous materials with varying dielectric properties, making it universally applicable to all tire types without requiring material-specific calibration or adjustment.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enables accurate and non-destructive thickness measurement of tires with both homogenous and heterogeneous materials, including those with metal reinforcement, by analyzing the frequency response of the system comprising the pads and tire material, facilitating reliable tire condition monitoring.

Implementation Method 1

The tire material may be homogenous or heterogeneous, and has dielectric properties

Methodology Applied
Scientific EffectDielectric: Dielectric

Implementation Method 2

measuring the signal reflected back to the first pad

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

determining a resonant frequency of a system based on the received signal; the system comprising the first pad, the second pad, and the tire; and determining the thickness of the tire based on the resonant frequency

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3400450B1Non-invasive thickness measurement using resonant frequency shift
Publication Date: 2021.10.13 DUKE UNIV
  • EP3400450B1 patent drawingFigure 1
  • EP3400450B1 patent drawingFigure 2
  • EP3400450B1 patent drawingFigure 3

AI summary

A method of measuring thickness of a material generally includes transmitting an oscillating signal from a first pad, through the material, to a second pad, and measuring the signal reflected back to the first pad. The material may be homogenous or heterogeneous, and has dielectric properties. The signal has its frequency varied over time so that the frequency response of the system (the first pad, the material, and the second pad) may be analyzed. The resonant frequency of the system is determined. The thickness of the material is determined based on the resonant frequency shift caused by a change in thickness of the material. The present invention may be advantageously employed to measure the thickness of a vehicle tire or other material. Related apparatuses are also disclosed.