A micro-transducer matrix design for the detection of flexural guided waves

Area of Science:

• Materials Science
• Acoustics
• Nondestructive Testing

Background:

• Ultrasonic guided waves are crucial for structural health monitoring in plates and cylinders.
• Existing detection methods face challenges in identifying specific wave modes, especially at low frequencies.
• Micro-transducer arrays offer potential for enhanced wave detection and mode analysis.

Purpose of the Study:

• To propose and validate a novel LiNbO3 single crystal-based micro-transducer matrix for ultrasonic guided wave detection.
• To investigate the matrix's capability in identifying Lamb and Pochhammer-Chree guided waves in various structures.
• To demonstrate the identification of the first flexural mode F(1,1) in cylindrical structures at low frequencies.

Main Methods:

• Design and fabrication of a LiNbO3 single crystal-based micro-transducer matrix.
• Characterization of the micro-transducer matrix using a network analyzer and laser Doppler vibrometer (LDV).
• Development of an experimental setup for acquiring electrical measurements and generating specific guided wave modes.
• Utilization of a phased array emitter with inverse polarization for selective flexural mode generation.

Main Results:

• Successful design and manufacturing of the LiNbO3 micro-transducer matrix.
• Demonstrated detection of Lamb and Pochhammer-Chree guided waves in plate-like and cylinder-like structures.
• Identification of the first flexural mode F(1,1) in cylinders at low frequencies.
• Validation of selective generation and detection of the F(1,1) flexural mode using the developed experimental setup.

Conclusions:

• The LiNbO3 micro-transducer matrix is effective for detecting ultrasonic guided waves.
• The study successfully identified the low-frequency flexural mode F(1,1) in cylinders.
• The developed system provides a promising approach for advanced structural health monitoring applications.