功能材料的力、电、磁耦合行为的实验研究

EXPERIMENTAL STUDY ON ELECTRO-MAGNETO-MECHANICAL COUPLING BEHAVIOR OF SMART MATERIALS

自行研制成功力—电、力—磁耦合加载设备,实现进行多场耦合实验;研究开发出力—电耦合场和力—磁耦合场下的力学量与电磁学量的量测技术,实现测量过程自动化;从而具备了同时对铁电材料施加应力场和电场的技术,对铁磁材料同时施加应力场和磁场的技术。解决了高电压的绝缘、防电弧放电、防电击穿、电荷测量与数据采集等难题,设计一系列有效的实验装置和实验环境。实验研究了耦合场作用下压铁电材料的本构关系,提出旨在消除内偏场的冲击极化方式;采用三点弯实验,测试了铁电材料的断裂韧度,发现极化方向对断裂韧度的显著影响。将云纹干涉技术应用于力电耦合场作用下裂尖变形场的测量。首次对预制有贯穿裂纹的铁电材料试件进行电疲劳实验,获得了电致疲劳裂纹扩展曲线,发现一些新的电疲劳损伤现象,例如不同载荷作用下裂纹的扩展模式、疲劳裂纹闭合效应、电致裂纹扩展的磨损与击穿等。实验制备并研究03联和13联铁电复合材料的介电性能、压电性能。制备PZTMgO纳米复相铁电陶瓷,在保证其压电性能的前提下,改善铁电材料的韧度。有关铁磁材料的实验研究,量测不同力磁耦合载荷作用下纯镍、6号镍、锰锌铁氧体、TerfenolD等几种铁磁材料的磁滞回线、磁致应变曲线,获得磁导率、磁致伸缩系数、压磁系数、磁弹性系数等。

New experiment systems, which are controlled by an industrial PC (computer) and can offer electromechanical or electromagnetic coupling loads, were designed and established. Automatization skills and technologies of measurement have been developed and the software was produced to monitor the testing process and to deal with the acquired data. The experimental difficulties and technical problems, such as insulation, discharge, electric breakdown and so on, have been well resolved. The constitutive experiments on piezo/ferroelectrics under coupling loads were first carried out. To eliminate the internal bias field, an impacting poling approach was developed. The effects of poling direction on the toughness of PZT-5 were investigated by means of three-point bending tests. Moir6 interferometry was applied to measure the domain transformation at crack tip in ferroelectric ceramics under coupling loads. The tests of electric fatigue on ferroelectric specimens with through pre-cracks were firstly conducted. The integrated curves of fatigue crack growth were obtained. Experimental phenomena, such as two types of crack growth mechanisms, fatigue crack closure, electric breakdown and so on, have been discovered and studied. To improve the fracture of the brittle ferroelectric ceramics, the PZT/MgO nano-composites were prepared. The experimental investigation on 0-3 and 1-3 piezocomposites was also carried out and novel experimental data were obtained. Several ferromagnetic materials were used to investigate magneto-mechanical coupling behavior, such as electrolytic nickel, Ni6, Manganese-Zinc ferrite ceramics, Terfenol-D, NiMnGa. The characteristic curves of ferromagnetic materials have been measured, including the hysteresis loops, the magnetostriction curve and stress-strain curve. To analyze the effects of magnetic field on toughness, three-point bending tests and Vicker's indentation tests were performed too.