Piezoelectric Wafer Active Sensor Transducers for Acoustic Emission Applications

Area of Science:

• Materials Science
• Mechanical Engineering
• Structural Health Monitoring

Background:

• Piezoelectric materials generate charge under mechanical strain, enabling sensing applications.
• Structural Health Monitoring (SHM) uses sensors to detect damage in infrastructure.
• Piezoelectric Wafer Active Sensors (PWASs) are increasingly used for SHM.

Purpose of the Study:

• Investigate a novel pitch-catch method for assessing PWAS instrumentation quality.
• Analyze the impact of defects in PWASs and their bonding on sensor response.
• Compare the pitch-catch method with the electromechanical impedance (EMI) method for defect detection.

Main Methods:

• Developed and applied a pitch-catch method to evaluate PWASs.
• Introduced defects in PWASs and bonding layers to simulate real-world conditions.
• Recorded and analyzed transmitted and received signals, as well as impedance spectra.

Main Results:

• The pitch-catch method successfully verified defect-free PWAS instrumentation and bonding.
• Defective PWASs and bonding resulted in reduced signal amplitude and altered frequency spectrums.
• The pitch-catch method identified specific signal changes for bonding defects (eliminated high frequencies) and broken PWASs (600 kHz amplitude increase).
• The EMI method showed distinct changes in impedance peaks for bonding defects and broken sensors.

Conclusions:

• The pitch-catch method is a viable technique for evaluating PWAS quality in SHM.
• Sensor and bonding defects significantly alter PWAS signal characteristics.
• Both pitch-catch and EMI methods can detect PWAS defects, but with different observable signatures.