Anisotropic Conductive Material Field Analysis via Rotated Conductivity Tensor

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Solution Overview

Problem

Current electromagnetic field analysis methods for anisotropic conductive materials, such as fiber-reinforced plastics, suffer from reduced approximation accuracy due to the assumption of identical electric fields at different positions in the Yee grid, leading to inaccurate calculations of electric current distribution.

Innovation Solution

The method employs a finite-difference time-domain analysis using a conductivity tensor representation, where the conductivity is rotated about an axis orthogonal to the fiber direction, allowing for the derivation of anisotropic conductivity in the x-y plane, and undefined electromagnetic field components are calculated by averaging surrounding defined components, enabling more accurate interpolation and iterative refinement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the assumption of identical electric fields at different positions is used in the Yee grid, then the analysis method is simple to implement, but the approximation accuracy is reduced

Engineering Contradiction:
Improveease of implementationVSAvoidapproximation accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the parameter handling approach by introducing a rotation angle θ to transform the conductivity tensor from the fiber coordinate system to the analysis grid coordinate system. This allows the conductivity components to vary with the rotation angle, enabling accurate representation of anisotropic conductivity without requiring the simplifying assumption of identical electric fields at different grid positions

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent adds a rotational dimension by introducing the rotation angle θ as a new parameter. The conductivity tensor is rotated about the z-axis by angle θ, transforming the problem from a fixed coordinate system to a rotated coordinate system that aligns with the fiber orientation. This dimensional addition enables accurate modeling of anisotropic materials while maintaining compatibility with the standard Yee grid structure

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If the conductivity tensor is rotated about the z-axis to represent anisotropic conductivity, then the anisotropic conductivity is accurately represented, but the calculation becomes more complex

Engineering Contradiction:
Improveconductivity representation accuracyVSAvoidcalculation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses parameter changes by expressing the rotated conductivity components (σxx, σyy, σxy, σyx) as functions of the rotation angle θ and the principal conductivity values (σ1, σ2). This parametric representation allows the conductivity tensor to adapt to different fiber orientations while maintaining a systematic calculation framework that does not significantly increase computational complexity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary action by pre-calculating the rotated conductivity tensor components based on the known fiber orientation angle θ before performing the electromagnetic field analysis. This pre-computation of the conductivity tensor allows the main FDTD simulation to proceed with standard algorithms, separating the complexity of tensor rotation from the time-critical electromagnetic calculation

Inventive Principle:
Principle #10Preliminary action

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

This approach enhances the accuracy of electromagnetic field analysis for anisotropic conductive materials by accurately modeling electric current distribution, particularly in fiber-reinforced plastics, improving the representation of anisotropic conductivity and current flow.

Implementation Method 1

a conductivity tensor obtained when conductivity defined in a coordinate system of the three orthogonal axes is rotated about an axis orthogonal to both of the first direction and the second direction

Methodology Applied
Scientific EffectConductivity tensor rotation: Anisotropy

Implementation Method 2

the conductivity tensor is applied to Ampere's expression and may subsequently be discretized by using a finite difference method

Methodology Applied
Scientific EffectFinite difference discretization:

Implementation Method 3

When performing calculation repeatedly by applying an iterative method to the discretized expression, an undefined electromagnetic field component included in the discretized expression may be calculated as the one electromagnetic field component from the electromagnetic field components

Methodology Applied
Scientific EffectIterative numerical solution:

Data Source

PatentEP3226148B1Electromagnetic field analysis method for anisotropic conductive material
Publication Date: 2018.11.21 SUBARU CORP
  • EP3226148B1 patent drawingFigure 1A~1B
  • EP3226148B1 patent drawingFigure 2A~2C
  • EP3226148B1 patent drawing

AI summary

Provided is an electromagnetic field analysis method for an anisotropic conductive material. The method involves using an analysis grid having a first side and a second side that are orthogonal to each other to analyze an electromagnetic property of an anisotropic conductive material in which conductivity in a first direction is different from conductivity in a second direction. One or both of the first direction and the second direction are parallel to a direction different from either one of the first side and the second side of the analysis grid. One electromagnetic field component located on the first side and extending along the second side is calculated based on electromagnetic field components that are located on the second sides surrounding the one electromagnetic field component and that extend along the second sides.