Title :
Measuring Lamb wave dispersion curves of a bi-layered plate and its application on material characterization of coating
Author :
Lee, Yung-Chun ; Cheng, Sheng-Wen
Author_Institution :
Dept. of Mech. Eng., Nat. Cheng Kung Univ., Tainan, Taiwan
fDate :
5/1/2001 12:00:00 AM
Abstract :
This paper investigates the Lamb wave dispersion curves of a bi-layered plate and evaluates the feasibility of using the dispersion data to characterize the coating´s material properties. The measurement of dispersion curves is based on a focusing PVDF transducer operating in a pulse/echo mode. An image displaying technique is used to determine the dispersion relation of Lamb waves from the measured data. Multiple dispersion curves of Lamb waves are accurately determined over a wide frequency range (4 to 20 MHz). Lamb wave dispersion curves for thin metal sheets electrodeposited with nickel coatings are measured. The elastic constants of the nickel coating are determined by comparing the experimental dispersion data with the theoretical ones calculated numerically. Potential applications of this measurement method are addressed.
Keywords :
acoustic signal processing; elastic constants; elastic moduli measurement; electrodeposits; nickel; protective coatings; surface acoustic waves; ultrasonic dispersion; ultrasonic materials testing; ultrasonic velocity measurement; waveform analysis; 4 to 20 MHz; FFT; Lamb wave dispersion curves; Ni; US NDT; bilayered plate; coating material characterization; dispersion curves measurement; elastic constants; electrodeposited; focusing PVDF transducer; image displaying technique; nickel coatings; phase velocities; pulse-echo mode; thin metal sheets; waveform processing; Acoustic measurements; Coatings; Dispersion; Frequency; Material properties; Pulse measurements; Surface acoustic waves; Ultrasonic imaging; Ultrasonic variables measurement; Velocity measurement;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on