Development of an electromagnetic acoustic transducer (EMAT) for the noncontact excitation of guided ultrasonic waves

P. Fromme

doi:10.1117/12.2083839

23 March 2015 Development of an electromagnetic acoustic transducer (EMAT) for the noncontact excitation of guided ultrasonic waves

P. Fromme

Author Affiliations +

Proceedings Volume 9438, Health Monitoring of Structural and Biological Systems 2015; 943806 (2015) https://doi.org/10.1117/12.2083839
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2015, San Diego, California, United States

Abstract

Fatigue damage can develop in aerospace structures at locations of stress concentration, such as fasteners. For the safe operation of the aircraft fatigue cracks need to be detected before reaching a critical length. Guided ultrasonic waves offer an efficient method for the detection and characterization of such defects in large aerospace structures. Noncontact excitation of guided waves was achieved using electromagnetic acoustic transducers (EMAT). The transducer development for the specific excitation of the A₀Lamb wave mode is explained. The radial and angular dependency of the excited guided wave pulses at different frequencies were measured using a noncontact laser interferometer. Based on the induced eddy currents in the plate a theoretical model was developed and reasonably good agreement with the measured transducer performance was achieved. The developed transducers were employed for defect detection in aluminum components using fully noncontact guided wave measurements. Excitation of the A₀ Lamb wave mode was achieved using the developed EMAT transducer and the guided wave propagation and scattering was measured using a noncontact laser interferometer. These results provide the basis for the defect characterization in aerospace structures using noncontact guided wave sensors.

Citation Download Citation

P. Fromme "Development of an electromagnetic acoustic transducer (EMAT) for the noncontact excitation of guided ultrasonic waves", Proc. SPIE 9438, Health Monitoring of Structural and Biological Systems 2015, 943806 (23 March 2015); https://doi.org/10.1117/12.2083839

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