Bottom Crack Detection with Real-Time Signal Amplitude Correction Using EMAT-PEC Composite Sensor.

Area of Science:

• Non-destructive testing
• Electromagnetic acoustic transducers (EMAT)
• Pulse eddy current (PEC)

Background:

• Electromagnetic ultrasonic testing faces challenges with small bottom cracks and probe lift-off fluctuations.
• Time of flight (ToF) limitations hinder accurate detection of small defects.
• Lift-off variations compromise the consistency and accuracy of inspection results.

Purpose of the Study:

• To develop a novel composite sensor integrating EMAT and PEC for improved detection of small bottom cracks.
• To address the limitations of traditional methods in handling lift-off interference.
• To enhance the accuracy and reliability of non-destructive testing for subsurface defects.

Main Methods:

• Designed a composite sensor combining EMAT and PEC technologies.
• Utilized EMAT for bottom echo amplitude analysis to identify cracks.
• Employed PEC signals to measure real-time average probe lift-off.
• Combined theoretical analysis and finite element method (FEM) to differentiate lift-off and crack effects.
• Developed a signal fusion method for amplitude correction.

Main Results:

• The composite sensor successfully detected bottom cracks as small as 0.1 mm x 0.3 mm.
• The signal fusion method effectively corrected defect signal amplitudes, reducing lift-off impact.
• The amplitude correction method achieved a relative error of less than ±8%.

Conclusions:

• The novel EMAT-PEC composite sensor offers a robust solution for detecting small bottom cracks.
• Signal fusion significantly improves the accuracy and consistency of non-destructive testing by mitigating lift-off effects.
• This integrated approach enhances the capability of inspecting critical components for subsurface flaws.