Lamb Wave Sensor Based on a Near-Stoichiometric LiNbO₃ Piezoelectric Crystal for High-Temperature Structural Health...

Area of Science:

• Materials Science
• Acoustics
• Engineering

Background:

• Structural Health Monitoring (SHM) relies on effective sensors.
• Ultrasonic guided wave sensors, specifically Lamb wave sensors, are crucial for SHM.
• Piezoelectric materials are key components in these sensors.

Purpose of the Study:

• To develop a Lamb wave sensor utilizing near stoichiometric lithium niobate (NSLN) piezoelectric single crystal.
• To investigate the piezoelectric properties and performance of NSLN for SHM applications.
• To demonstrate the sensor's effectiveness at elevated temperatures.

Main Methods:

• Designed an optimum crystal cut for NSLN to enhance piezoelectric properties.
• Fabricated and tested NSLN-based Lamb wave sensors.
• Evaluated sensor performance, including signal voltage and signal-to-noise ratio (SNR), at room and high temperatures (up to 650°C).

Main Results:

• NSLN exhibited superior piezoelectric properties due to its finer domain structure and higher domain density.
• The optimized NSLN crystal cut achieved a piezoelectric coefficient (d32') of -34.3 pC/N, a 16.3-fold increase.
• NSLN-based sensors effectively transmitted and received Lamb waves, showing signal voltages of 227.3 mV (room temp) and 3.0 mV (650°C).
• The sensor demonstrated good defect localization with an SNR of 23.2 dB at 650°C.

Conclusions:

• NSLN is a promising material for high-temperature ultrasonic guided wave sensors.
• The developed NSLN-based Lamb wave sensor shows significant potential for in situ SHM in harsh environments.
• Optimized crystal cuts are vital for maximizing the performance of piezoelectric sensors.