【作者】 卢建锋； 梁旭； 申胜平；

【Author】 Lu Jianfeng;Liang Xu;Shen Shengping;School of Mechanical Engineering, Changshu Institute of Technology;State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’an Jiaotong University;

【机构】 常熟理工学院； 西安交通大学；

【摘要】 挠曲电效应(Flexoelectric effect)作为一种普遍存在于介电材料中的力电耦合效应,描述了由应变梯度局部破坏晶体反演对称性导致的中心对称和非中心对称晶体中出现的极化现象。本文以聚偏氟乙烯材料(Polyvinylidene fluoride, PVDF)作为研究对象,实验研究了块体PVDF材料中的纵向挠曲电系数。作者通过直接测量电荷的方法建立了变截面试件中应变梯度与电荷之间的关系,并发展了一种较为精确的纵向挠曲电系数测试方法;设计了可测量不同温度对材料挠曲电效应影响的实验装置,并以圆台形试件作为实验组,圆柱形试件作为对照组实验研究了温度对PVDF材料挠曲电效应的影响;实验发现挠曲电系数随载荷温度、频率的变化呈非线性变化趋势,并非保持不变。基于此,我们认为聚偏氟乙烯材料相比于铁电陶瓷材料在能量收集方面有更好的应用前景。更多还原

【Abstract】 Flexoelectricity describes the generation of electric polarization in dielectric solid of all symmetry groups by the application of an elastic strain gradient. In this paper, the bulk polyvinylidene fluoride(PVDF) material is used to explore the longitudinal flexoelectric effect. The relationship between the strain gradient and tharge in variable cross-section sample is established based on the charge measurement, an improved approached to measure the flexoelectric coefficient is developed. The truncated cone bar is used as a test sample while the cylinder bar is used for comparison. We report the observation of the temperature dependence of the flexoelectric coefficient μ11 in bulk polyvinylidene fluoride in the current work, and also we calculated the flexocoupling coefficient based on the experimental data. The greater temperature stability for the flexoelectricity in bulk polyvinylidene fluoride is found in our experiments due to the broad dielectric stability. Besides the interesting observation, we dedicate that the polymer polyvinylidene fluoride is much better than flexoelectric-ceramics for energy harvesting applications.更多还原