Seung Il Cho

RESPONSE OF A 1-3 PIEZOELECTRIC COMPOSITE TRANSDUCER FOR ELASTIC WAVES GENERATED DURING GLASS CAPILLARY BREAKAGE

The 1-3 piezoelectric composite transducer with the 60% volume fraction of the PZT-5A was fabricated by the dicing-filling method. The electrical and acoustical characteristics of the 1-3 piezoelectric composite transducer were compared and analyzed by the electrical impedance measurements and the pulse-echo method. The mechanical quality coefficient (Q) and the resonant frequency were 18.5 and 1.6 MHz, respectively. The elastic waves generated during glass capillary breakage were observed by 1-3 piezoelectric composite transducer. The observed AE signals are well matched with the perpendicular component of the particle velocity calculated by computer. The observed AE signal and its frequency spectrum show that the pulse-type signals of AE observed by 1-3 piezoelectric composite transducer may be depend on the the vibration mode of thickness with the plate response of the wide band.

Study for Dynamic Characteristics of the Accelerometer Mounting Fixtures

Accelerometer mounting fixtures were prepared with the different materials(Ti and SUS). The dynamic characteristics of the mounting fixture were analyzed by finite element method(FEM), and the mode shape of each order and the displacement response for modelling the mounting fixture were analyzed by ANSYS, then resonant frequencies of the mounting fixtures with Ti and SUS were 22.700 and 23.390 kHz, respectively. The dynamic characteristics of the mounting fixture with the different positions were obtained by using laser interferometer. The response of the accelerometer was nearly a constant from 40 Hz to 500 Hz, but the change of the acceleration was increased with an increase of the frequency above 500 Hz.

The Measurements of Vibration Displacement of the Piezoelectric Exciter Using Mach-Zehnder Optical Fiber Interferometer

The vibration exciter with the accurate calibration requires a low distortion along a single axis over a wide range of frequency. The fabricated piezoelectric exciter was composed of a base, piezoelectric element(Venitron PZT 5A), electrode and seismic mass. Its performance characteristics is evaluated the Mach-Zehnder optical fiber interferometer. The phase of the optical wave passing through the optical fiber around the piezoelectric element was related the vibrational amplitude with a change of the applied sinusoidal voltage on the piezoelectric element. The dynamic characteristics of vibration exciter can be obtained by measuring the vibrational amplitude with a sinusoidal applied voltage on the piezoelectric element. The sensitivity of the fabricated piezoelectric exciter had a 0.4 nm/V which was uniform up to 20 kHz.

Automation of Primary Vibration Calibration System Using Laser Interferometer

An automation of primary vibration calibration system was developed and tested. Using GPIB interface, the console PC make the control of equipments, signal collecting and save measuring results automatically by the instructions in the program by Visual Basic. Several trials of automatic calibration for the accelerometer(ENDEVCO 2270) using this developed system give the reliable results.