Multilayer Structure Characterization Using Transient Electromagnetic Reflection
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Solution Overview
Problem
Current methods for characterizing layer-based structures, such as multilayer structures, are inadequate for new materials like rubber and soft plastics, and struggle with detecting delamination and micro-structural defects in materials like High Density Polyethylene, especially when traditional techniques like ultrasonic testing and radiography are ineffective due to absorption or access limitations.
Innovation Solution
A method using continuous wave electromagnetic radiation to determine geometric and electromagnetic properties of layer-based structures by capturing and analyzing transient reflections or transmissions, allowing for non-destructive characterization without the need for multiple frequencies or access to both sides of the material, and capable of identifying defects and layer thickness with high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ultrasonic testing is used for rubber or soft plastic, then the testing can be performed on traditional materials, but the polymers absorb nearly all sound energy and reflect essentially no sound waves making the testing ineffective
Solution Approach 1:
The patent changes the physical parameter of the testing wave from acoustic (ultrasonic) to electromagnetic radiation. This fundamental parameter change allows the testing method to work on materials like rubber and soft plastics that are incompatible with ultrasonic testing, as these materials do not absorb electromagnetic radiation in the same way they absorb sound waves.
Solution Approach 2:
The patent replaces the mechanical ultrasonic testing system with an electromagnetic radiation-based system. Instead of using mechanical sound waves that are absorbed by polymers, the system uses electromagnetic waves that can penetrate and reflect off the materials, enabling reliable detection of defects and layer characteristics.
2Measurement precision
If radiography is used to detect delamination, then bulk density changes can be detected, but delamination does not result in detectable change in local density making it undetectable
Solution Approach 1:
The patent replaces radiography (which detects bulk density changes) with electromagnetic reflection-based testing. This substitution allows detection of delamination by measuring reflection coefficient changes at layer interfaces, which occur even when there is no significant bulk density change, thereby enabling detection of delamination that radiography cannot detect.
Solution Approach 2:
Instead of detecting delamination through transmission and bulk density changes (as radiography does), the patent inverts the approach by using reflection measurements. The system measures the reflection coefficient at different frequencies and depths, detecting delamination through changes in reflected signal rather than transmitted signal, thereby achieving detection capability for interfaces with minimal density change.
3Ease of operation
If through-transmission air-coupled ultrasonic testing is used, then testing can be performed on materials, but access to both sides of the sample is required which is not always possible
Solution Approach 1:
The patent creates a universal testing system that functions effectively in both through-transmission and single-side reflection modes. By measuring reflection coefficients at multiple frequencies and using signal processing to extract depth information, the system provides versatile capability that adapts to different access conditions, making it universally applicable whether one-sided or two-sided access is available.
4Measurement precision
If Nicolson-Ross-Weir method is used for single layer characterization, then complex permittivity and permeability can be extracted, but ultra-width band with high frequency resolution is needed making it challenging for thin layers
Solution Approach 1:
The patent uses reflection coefficient measurements at multiple discrete frequencies rather than requiring ultra-wideband continuous frequency scanning. By selecting specific frequency points and using signal processing to interpolate and extract properties, the system achieves accurate characterization of thin layers without the excessive frequency resolution requirements of the Nicolson-Ross-Weir method, reducing device complexity while maintaining measurement precision.
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 determination of geometric and electromagnetic properties of layers in multi-layer structures, including thickness and defect detection, with improved depth and lateral resolution, suitable for various industries like construction, automotive, and piping, without requiring ionizing radiation or access to both sides of the material.
Implementation Method 1
capturing from the repetitive irradiating as a function of time a transient part of the reflection of the continuous wave electromagnetic radiation reflected at different interfaces of the structure
Data Source
AI summary
A method for determining characteristics of a structure is disclosed. The method comprises repetitively irradiating the structure with a transient continuous wave electromagnetic radiation and capturing as a function of time a transient part of the reflection or transmission of the transient continuous wave electromagnetic radiation reflected at or transmitted through the different interfaces of layer-based structure. The method furthermore comprises deriving from the transient part of the reflected or transmitted transient continuous wave electromagnetic radiation as function of time information regarding different contributions in the transient part of the reflected or transmitted transient continuous wave electromagnetic radiation stemming from the reflections at different interfaces of the structure and determining from said information at least geometric information and/or electromagnetic properties of the one or more materials of the structure. A corresponding system also is claimed.