报告题目：Characteristic of piezoelectric properties under high-load conditions —

 ISO 21819-2:2018(E): Electrical transient response method under high vibration levels

 报告人：Prof. Tomoaki Karaki (Toyama Prefectural University, Japan)

 报告时间：2024年3月15日（周五）下午4：00

 报告地点：明故宫校区A8号楼605会议室

 主办单位：航空航天结构力学及控制全国重点实验室、航空学院、校科协、国际合作处

 报告内容简介：

High power piezoelectric materials have a wide range of applications in piezoelectric actuators, piezoelectric linear stages, ultrasonic motors, ultrasonic welding, ultrasonic cleaning, piezoelectric transformers and other devices. Traditional piezoelectric characterization is based on the small-signal constant-voltage method, and the results of the test can be very different from the actual high-power use. The constant current method can test the piezoelectric properties under large loads, but the temperature of the sample rises continuously during the test, which affects the accuracy of the test. In 2016, Japanese scientists proposed a test method for the electrical transient response method under high vibration levels (Japanese Industrial Standard JIS R 1699-2: 2016), which can complete the measurement in less than 0.3 seconds, avoiding the temperature rise of the sample, and can accurately characterize the piezoelectric properties under large loads, providing an effective method for the research and development of high-power piezoelectric materials. The characterization method was designated as an international standard in 2018 (IOS 21819-2: 2018(E)).

This lecture gives an introduction for electrical transient response method under high vibration levels. Samples that have been stabilized for 48 hours after poling process, with approximately 35mm long, 4mm wide, and 0.5mm thick (top and bottom electrodes), could be used for the test. A 4-quadrant power supply is used to add approximately 100 Vp-p for 0.1 seconds and then the power is turned off. A current probe and a laser Doppler meter are applied to measure the change of current and displacement speed up to 0.2 seconds after the power is turned off. It is possible to calculate d31*, Qm* and the maximum stress at the center of the sample Tm* for different powers or vibration speeds, as well as the mechanical energy density Pm and the mechanical loss density (which corresponds to the heating power density) Pd.

 This method is suitable for the characterization of transverse effect length vibration modes under a high power. For longitudinal effect length vibration modes, however, use of larger power supplies and precision current probes are required.

 报告人简介：

  Tomoaki KARAKI (Zhiming CHEN) received a B Eng. Degree from Shanghai University of Science and Technology in 1982, received an M. Eng. degree from Shanghai Institute of Ceramics, Chinese Academy of Sciences in 1985, and received a Ph.D. degree from Kyoto Univ. Japan in 1996. After joining Toyama Prefectural Univ. in 1993, his research focused on single crystal growth, preparation of ceramics and films in piezoelectric, dielectric, and ferroelectric fields, including (i) alternating current poling (ACP) of piezoelectric relaxor-PbTiO3 single crystals, (ii)preparation of lead-free piezoceramics, (iii) growth of piezo- and ferroelectric single crystals, (iv) simulation of multilayer SAW devices, (v) characterization of acoustic wave related physical constants in piezoelectric single crystals, and others.