This study presents the experimental results completed to compare both performance of a special ultrasonic sensor and a Hall Effect sensor under the same measurement condition in order to assess the effectiveness, the proper installation, the convenience of use, and the costs of both methods. A special ultrasonic sensor is generally called Electromagnetic Acoustic Transducer (EMAT) which consists of magnet and sensor coil. It was tuned that ultrasonic wave with 1 MHz can be injected and detected. Sensor coils were separated to the transmitter and the receiver and placed at two surfaces of the specimen (top and bottom) to set the Lorentz force in parallel direction of the specimen surfaces [1]. This type of EMAT can generate the transverse wave (shear ware) for analyzing the wavelength from measurement. In application, the output voltage from Hall Effect sensor was then compared to the reference voltage in comparator circuit and then amplified the difference to gain 20 times and converted to frequency domain for better resolution at the specific set point of 8 kHz. From experiment, use of Hall Effect sensor exhibited high efficiency over that of EMAT method due to less complexity of the system, lower cost, as well as ease and convenience of installation. Moreover, application of EMAT method with the small size of specimen would lead the error and standard deviation by up to 4.51% and 0.279, respectively compared to that of Hall Effect sensor that can exhibit less error and standard deviation by about 0.24% and 0.013, respectively.

Date Published: 2 June 2014
PDF: 5 pages
Proc. SPIE 9234, International Conference on Experimental Mechanics 2013 and Twelfth Asian Conference on Experimental Mechanics, 92340R (2 June 2014); doi: 10.1117/12.2049712

Published in SPIE Proceedings Vol. 9234:
International Conference on Experimental Mechanics 2013 and Twelfth Asian Conference on Experimental Mechanics
Somnuk Sirisoonthorn, Editor(s)