GMR Sensor Corrosion Evaluation Under Non-Magnetic Covering
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Solution Overview
Problem
The Magnetic Flux Leakage Method using hall elements struggles to perform precise quantitative evaluation of corrosion in steel materials covered by non-magnetic materials like concrete due to low magnetic sensitivity, and existing electrochemical methods can only determine the presence of corrosion but not quantify it.
Innovation Solution
A corrosion evaluation device employing a GMR sensor with a bridge circuit to detect magnetic flux leakage and calculate thickness reduction in magnetic materials covered or not covered by non-magnetic materials, using a magnetic field generated by permanent magnets and a direct-current power supply to convert magnetic flux changes into electrical signals for precise thickness measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hall element is used as a magnetic sensor to detect magnetic flux leakage, then the device structure is simple, but the magnetic sensitivity is weak and quantitative evaluation of corrosion is difficult when steel material is covered by non-magnetic material
Solution Approach 1:
The patent changes the fundamental parameter of the sensor from hall element to GMR element, which operates on different physical principles (giant magnetoresistance effect). This parameter change enables significantly higher magnetic sensitivity while allowing the sensor to function effectively through non-magnetic materials like concrete, resolving the contradiction between sensitivity and measurement capability under coverage.
Solution Approach 2:
The patent replaces the hall element-based magnetic sensing mechanism with a GMR element-based mechanism. The GMR element converts magnetic flux changes directly into electrical resistance changes, which are then converted to voltage signals. This substitution provides superior magnetic sensitivity and enables quantitative corrosion evaluation even when the steel material is covered by non-magnetic materials.
2Measurement precision
If electrochemical measurement methods are used to detect corrosion of steel material covered by non-magnetic material, then the presence of corrosion can be determined, but quantitative evaluation cannot be performed
Solution Approach 1:
The patent replaces electrochemical measurement methods with a magnetic field-based detection method using GMR sensors. By applying a magnetic field to the steel material and detecting magnetic flux leakage through the non-magnetic covering material, the system achieves quantitative measurement of corrosion (thickness reduction) while maintaining the ability to detect through concrete or other non-magnetic materials.
Solution Approach 2:
The patent uses a magnetic field as an intermediary to transmit information from the steel material through the non-magnetic covering material to the GMR sensor. The magnetic field penetrates the concrete or other non-magnetic materials without significant attenuation, enabling the sensor to detect magnetic flux leakage and calculate corrosion quantitatively despite the covering material being present.
3Reliability
If steel material is covered by non-magnetic material such as concrete, then protection and structural integrity are improved, but precise detection of magnetic flux leakage and quantitative evaluation of corrosion become difficult
Solution Approach 1:
The patent employs a magnetic field as an intermediary that can penetrate non-magnetic materials like concrete. The magnetic field is applied to the steel material, and the GMR sensor detects the magnetic flux leakage through the non-magnetic covering material. This allows corrosion evaluation to be performed accurately while the steel material remains protected and covered, maintaining both structural integrity and measurement precision.
Solution Approach 2:
The patent changes the detection approach by using GMR elements that are highly sensitive to magnetic field changes and can detect magnetic flux leakage through non-magnetic materials. This parameter change in sensor technology enables accurate corrosion measurement without requiring the steel material to be exposed, thus maintaining the protective covering while achieving precise evaluation.
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 GMR sensor's higher sensitivity allows for precise detection of magnetic flux leakage even under non-magnetic material coverage, enabling reliable quantitative evaluation of corrosion in reinforcing steel or steel plates, thus overcoming the limitations of previous methods.
Implementation Method 1
a GMR sensor, which includes a GMR element for detecting a magnetic flux leakage with regard to the magnetic material, for converting the change in the magnetic flux to an electrical signal
Implementation Method 2
a magnetic field generating device for generating such a magnetic field that includes the magnetic material in a magnetic path
Data Source
AI summary
A corrosion evaluation device for performing a quantitative evaluation of corrosion by measuring a quantity of decrease in the thickness of a magnetic material which is covered by a non magnetic material or a magnetic material which is not covered by a non magnetic material which includes: a magnetic field generating device for generating such a magnetic field that includes the magnetic material in a magnetic path, a Giant Magnet-Resistive effect (GMR) sensor provided with a GMR sensor for detecting a magnetic flux leakage with regard to the magnetic material and converts a change in the magnetic flux into an electrical signal, a thickness reduction calculation portion for calculating a quantity of decrease in the thickness of the magnetic material based on the electrical signal. The corrosion evaluation device precisely performs a quantitative evaluation of corrosion even when the magnetic material, which is to be evaluated, is covered by a non magnetic material.