Papers by Author: Bao Yuan Sun

Abstract: A piezoelectric thrust-measuring platform with high natural frequency is developed for measuring the pulsed thrust generated by attitude-control rocket engines. It consists of two shear mode piezoelectric quartz crystal sensors and an integral shell. The sensors are inserted into the grooves of the elastic rings with an interference fit. Shell stiffness is calculated by energy method (EM) and finite element method (FEM). The shell is optimized for obtaining a good compromise between the sensitivity and frequency response. The stiffness and natural frequency after optimization are verified by experiments. The results show that the stiffness calculated by FEM is more accurate than that calculated by EM. The sensitivity of the thrust-measuring platform is increased by 13.6% compared with before optimization. The natural frequency of the thrust measurement system is 1245 Hz.

Abstract: According to the results of mechanical property tests, the mechanical properties of heterogeneous composite-Patinopecten yessoensis (scallop) shells are anisotropic and related closely to the microstructure. The results of compression and three-point bending tests indicated that the compressive strength which vertical load on the shell surface was approximately 3.8 times than the parallel case. The bending strength which applied to the external of the shell was about 2.2 times than it loaded from the inner surface. Patinopecten yessoensis (scallop) shell is organic-inorganic composite and has different microstructure in different location in according to its functional requirements. Patinopecten yessoensis (scallop) shell is typical bioactive functional gradient material, and its microstructure is worthy of heterogeneous composite material parts design.

Abstract: In the paper, a new multilayer composition thin film thermocouple was developed, which can accurately measure the temperature nearby cutting edge in convenient and fast ways. By means of advanced Twinned microwave ECR plasma source enhanced Radio Frequency (RF) reaction non-balance magnetron sputtering technique, SiO2 insulating film, NiCr/NiSi sensor film and SiO2 protecting film were deposited on the surface HSS substrate. Both static calibration and dynamic calibration were completed. The results showed that the sensor had good performance, good linearity, quick dynamic response, response time constant was 12.7ms. The temperature near the cutting edge in cutting process of aluminum alloy was measured by the developed sensor. The bonding strength between multiple layer film and substrate of high-speed-steel met the presupposed demands.

Abstract: This paper aims to make piezoelectric ceramic actuator self-sense its own displacement in the absence of independent sensor. It is derived from the basic piezoelectric equation that the free charge on the wafer of piezoelectric ceramic actuator contains displacement information. So a displacement self-sensing method based on integrate circuit is presented. Voltage driving circuit for the piezoelectric ceramic actuator and integrated circuit for gathering free charge are designed. Based on the proposed compound circuits, the actuator can sense its own displacement while actuation. It is convenient to adjust the circuit and easy to acquire sensitive signal by using this method, and the impedance mismatching problem met in bridge method is overcome. The experimental results show that piezoelectric self-sensing actuator can effectively measure its displacement signal under the conditions of different wave form of driving voltage and different driving voltage frequency.

Abstract: People apply quartz dynamometers to measure of milling force extensively. It is mainly made from piezoelectric quartz sensor. In this paper, the theory of the secondary piezoelectric effect is deduced by four kinds of piezoelectric equations. With the measuring the quartz stack secondary piezoelectric effect is verified. By theory and experiment we can show that the secondary piezoelectric effect makes elastic compliance constant of piezoelectric quartz smaller and do elastic stiffness constant of piezoelectric quartz bigger. Obviously, the secondary piezoelectric effect will have direct effect on the measuring precision of quartz dynamometers. So the investigations of secondary piezoelectric effect contribute to improving measuring precision of piezoelectric dynamometers.