• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.71-74
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• 2007

The objective of this presentation is to introduce a recent development of a magnetostrictive grating technique using an optimal yoke to efficiently generate and measure SH (Shear-Horizontal) waves in a plate. Gratings are effective means to generate frequency-tuned waves, but the gap between magnetostrictive gratings inevitably obstructs magnetic flow. Because magnetic field is the main physical quantity to actuate and sense ultrasonic waves, the transducer performance is most significantly influenced by the magnetic field distribution in the strips. Thus, wave transduction efficiency can be substantially improved if better magnetic flow is formed in the strips. To improve the efficiency, the topology optimization method was used to determine an optimal yoke configuration. A series of experiments on an aluminum plate were conducted using a grating with and without the designed yoke; when the yoke was used, the signal outputs increased up to 60 %.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.575-585
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• 2015

Magnetic field in magnetic bearings is the physical medium to realize magnetic levitation, the distribution of the magnetic field determines the operating performance of magnetic bearings. In this paper, a thin-slice Fiber Bragg Grating-Giant Magnetostrictive Material magnetic sensor used for the air gap of magnetic bearings was proposed and tested in the condition of dynamic magnetic field. The static property of the sensor was calibrated and a polynomial curve was fitted to describe the performance of the sensor. Measurement of dynamic magnetic field with different frequencies in magnetic bearings was implemented. Comparing with the finite element simulations, the results showed the DC component of the magnetic field was detected by the sensor and error was less than 5.87%.