Design and Study of Pulsed Eddy Current Sensor for Detecting Surface Defects in Small-Diameter Bars

Area of Science:

• Materials Science and Engineering
• Non-Destructive Testing
• Electromagnetism

Background:

• Surface defects in small-diameter rods pose significant challenges for quality control.
• Accurate detection requires optimized sensor design and advanced detection technologies.

Purpose of the Study:

• To present the construction of a non-coaxial differential eddy current sensor (Tx-Rx sensor).
• To examine the detection of surface defects in small-diameter bars.
• To develop a quantitative model for defect depth assessment.

Main Methods:

• Development of a COMSOL 3D model to simulate eddy current distribution and defect signals.
• Optimization of Tx-Rx sensor parameters: coil dimensions, separation, and elevation.
• Establishment of an experimental system for defect detection in bar structures.
• Correlation of differential signal attenuation with defect depth.

Main Results:

• Simulation revealed variations in eddy current distribution and defect signal characteristics between plates and rods.
• Optimized sensor design enhanced detection capabilities.
• A model was proposed correlating signal attenuation with defect depth.
• Quantitative relative error for defect depth detection was less than 5%.

Conclusions:

• The developed non-coaxial differential eddy current sensor effectively detects surface defects in small-diameter bars.
• The proposed model provides a reliable method for quantitative defect depth measurement.
• This research offers a valuable reference for non-destructive evaluation of bar surface integrity.