Dissertation > Industrial Technology > Automation technology,computer technology > Automation technology and equipment > Automation components,parts > Transmitter ( converter),the sensor

PVDF Piezoelectric Film Transducer and Its Application to Measurement of Shock Wave in Liquid

Author ZhangLiHong
Tutor WangZuo
School Nanjing University of Aeronautics and Astronautics
Course Mechanical Manufacturing and Automation
Keywords shock wave piezoelectric PVDF Hopkinson bar Piezoelectric transducer KZK
Type Master's thesis
Year 2008
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The shock wave processing technology is one kind of new processing technology based on ultrasound technology. Currently, high-intensity focused ultrasound(HIFU) technology research and application has been made certain achievements in world wide. The success of HIFU tells that the ultrasound technology has already got very good application in medical science field, and also provided the basis for the research of shock wave technology. Shock wave as a means of processing, its effect of processing and treatment is closely related to the characteristics of the shock wave. So, measuring the characteristics of shock wave is apparently important. In view of the defects of traditional measuring methods such as small range and complex operation, developing measurement system for a shock wave processing has become the first and foremost task.On the basis of the non-linear equation KZK, the characteristics of kinetic response process of pressure, distribution, shock wave’s Interaction of shock wave impact field and the impact of testing system were simulated to provide theoretical basis for the experiment. In this research, the full use of characteristics of PVDF piezoelectric film such as high Dielectric strength, high frequency response, high mechanical strength, stable chemical performance meet the measurement demand of liquid shock wave which is of High-temperature, high pressure and high strain, and on the basis of it, PVDF piezoelectric sensors for liquid shock wave testing were developed, and piezoelectric coefficient was calibrated with Hopkinson bar. Then a shock wave testing system was established to test and study on the liquid shock wave system. The testing results show that the maximum value of shock wave pressure increases with the incentive voltage and the unit number, which is also related with the focus form. In the transmiting process, the power of the shock wave is decaying, and echo is created, which can disturb the incentive output. The parameters of each element effects on the multi-array-element system are different, and phase and frequency of each waveform are different too, so the superposition of the waveforms appears to be amplitude modulated. The test method adopting array sensors can completely establish the pressure distribution of both planar and focused shock wave. Compared with the piezoelectric ceramic sensors, the frequency response and stability of PVDF Piezoelectric sensors appear higher. Finally, with the comprehensive analysis on a large number of experimental and theoretical simulation data characteristics of the liquid shock wave were understood more intuitively,which specify in the direction of further study on the shock wave processing system.

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