Magnetic Dipole Density for Defect Depth Estimation

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Solution Overview

Problem

Existing material defect detection systems in metallic equipment struggle to estimate shape information such as planar shape and depth of defects due to variations in defect shapes and sensor positions, requiring numerous predefined patterns which is impractical.

Innovation Solution

A material defect detection system utilizing a magnetic sensor array and a measurement management device that computes magnetization direction, calculates magnetic dipole density distribution, and estimates depth distribution of defects based on measured magnetic field distributions, integrating and optimizing data to determine defect shape without relying on pattern matching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pattern matching is used to detect material defects, then defect presence can be detected, but shape information such as planar shape and depth cannot be estimated

Engineering Contradiction:

Improvedefect detection capabilityVSAvoidshape information

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The invention transitions from two-dimensional magnetic field measurements to three-dimensional magnetic field distribution measurements by adding measurements in the depth direction (z-axis). This dimensional expansion enables the system to capture depth information of defects, allowing estimation of both planar shape and depth through tomographic reconstruction techniques similar to medical CT scanning.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of information

If material defect patterns are prepared for various defect shapes and standoffs to estimate shape information, then shape estimation becomes possible, but the system complexity increases due to requiring a great number of patterns

Engineering Contradiction:

Improveshape informationVSAvoidnumber of predefined patterns

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

Instead of preparing numerous predefined patterns for different defect shapes and positions, the invention changes the measurement parameters by acquiring magnetic field distributions at multiple depths (z-direction measurements). This parameter change enables shape estimation through mathematical reconstruction from the multi-depth data, eliminating the need for extensive pattern libraries.

Inventive Principle:

Principle #35Parameter changes

3Loss of information

If magnetic field distribution measurements are taken at multiple depths, then shape information can be estimated, but measurement time and system complexity increase

Engineering Contradiction:

Improvedepth distribution informationVSAvoidmeasurement time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The invention performs preliminary magnetization of the metallic equipment before defect detection measurements. This preliminary action establishes a known magnetic field distribution that serves as a reference, enabling faster and more accurate defect detection by comparing measured fields against the pre-established magnetization state, thereby reducing overall measurement time.

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

Enables efficient estimation of material defect shape information in metallic equipment, reducing the need for numerous predefined patterns and improving practicality in defect detection.

Implementation Method 1

detecting a material defect in a predetermined region of a metallic equipment using a magnetic field distribution in the predetermined region measured by the magnetic sensor array

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

compute a magnetization direction in the predetermined region of the metallic equipment based on the magnetic field distribution measured by the magnetic sensor array

Methodology Applied

Scientific EffectMagnetization: Magnetism

Implementation Method 3

calculate a density distribution of magnetic dipoles in the predetermined region based on the magnetic field distribution measured by the magnetic sensor array and the magnetization direction computed by the magnetization direction computer

Methodology Applied

Scientific EffectMagnetic dipole: Magnetism

Data Source

PatentEP3537144B1Thickness loss detection device, thickness loss detection system, thickness loss detection method, and program

Publication Date: 2022.11.23 YOKOGAWA ELECTRIC CORP

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AI summary

A material defect detection device, a material defect detection system, a material defect detection method, and a program which can easily estimate shape information of a material defect are provided. A material defect detection device for detecting material defect in a predetermined region of a metallic equipment using a magnetic field distribution in the predetermined region measured by a magnetic sensor array, the material defect detection device being provided with a magnetic dipole density distribution calculator for calculating a density distribution of magnetic dipoles in the predetermined region based on the magnetic field distribution measured by the magnetic sensor array, and a depth distribution calculator for calculating a depth distribution of material defect in the predetermined region based on the density distribution of the magnetic dipoles.