压电薄膜剪切压电应变特性的研究

Piezoelectric thin films are key materials for micro piezoelectric devices, such as high sensitive sensors, low voltage actuators, and micropower energy harvester, which have been widely used in micro-electromechanical systems (MEMS). Piezoelectric thin films with flexible substrates, exhibiting the advantages of good toughness, flexible, easy to manufacture and integrate, are the promising materials for micro MEMS devices. For piezoelectric materials, the piezoelectric strain coefficients are usually in the order of d15>d33>d31. Utilizing piezoelectric thin films with large piezoelectric shear strain coefficient d15, high performance shear mode piezoelectric thin film devices can be designed and manufactured. However, techniques for accurate characterization of the piezoelectric shear strain coefficient d15 of thin films are lack, which restricts the wide application of piezoelectric thin film devices. In this project, the piezoelectric constitutive equations which consider the effects of residual stress and shear strain are introduced into the Timoshenko beam model. A model of shear mode piezoelectric thin film cantilever beam with flexible metal substrate is developed. The coupling relationships of multi-variables considering the effect of residual stress are analyzed. Subsequently, the piezoelectric shear strain coefficient d15 of piezoelectric thin films is measured experimentally. Finally, an accurate experimental method is proposed to characterize the piezoelectric shear strain coefficient d15 of piezoelectric thin films. It would provide instructive guidance for accurately measuring the shear properties of piezoelectric thin films and designing shear mode piezoelectric thin films devices.

压电薄膜是高灵敏传感器、低电压驱动器以及微功率能量收集器等微型压电器件的关键材料，被广泛地应用在微机电系统(MEMS)中。柔性衬底压电薄膜具有韧性好、可弯曲、易加工和便于集成化等诸多优点，是微型MEMS器件极具潜力的材料。压电材料通常具有压电应变系数d15>d33>d31的特点。利用具有较大剪切压电应变系数d15的压电薄膜，可以设计和制作性能优异的剪切模式压电薄膜器件。然而，缺乏准确测量压电薄膜剪切压电应变系数d15的实验方法制约了压电薄膜器件的发展。本申请项目通过将考虑剪切变形和残余应力的压电本构关系引入铁摩辛柯梁模型中，构建一种具有柔性金属衬底的剪切模式压电薄膜悬臂梁装置模型，解耦考虑残余应力影响的多变量耦合关系，实验测量压电薄膜剪切压电应变系数d15，最终提出一种精确测量压电薄膜剪切压电应变系数d15的实验方法，为压电薄膜剪切性能表征和剪切模式压电薄膜器件设计提供指导。

压电薄膜是高灵敏传感器、低电压驱动器以及微功率能量收集器等微型压电器件的关键材料，被广泛应用在微机电系统中。利用具有较大剪切压电应变系数d15的压电薄膜，可以设计和制作性能优异的剪切模式压电薄膜器件。然而，缺乏准确测量压电薄膜剪切压电应变系数d15的实验方法制约了压电薄膜器件的发展。本项目通过将考虑剪切变形和残余应力的压电本构关系引入铁摩辛柯梁模型中，构建一种新型的剪切模式压电薄膜悬臂梁装置模型，并解耦考虑残余应力影响的多变量耦合关系，实验测量压电薄膜剪切压电应变系数d15，最终提出一种精确测量压电薄膜剪切压电应变系数d15的实验方法，为压电薄膜性能表征和器件设计提供指导。所取得成果如下：. 区别于传统拉伸变形模式，将考虑剪切变形的压电本构关系引入铁摩辛柯梁模型中，构建了一种考虑残余应力影响的新型剪切模式压电薄膜悬臂梁装置理论模型。该理论模型属于全新的研究内容，具有原创性。. 解耦了考虑残余应力影响，以电场、电位移、应力和应变为基本参量的剪切模式压电薄膜悬臂梁多变量耦合关系，获得了剪切压电应变系数d15与悬臂梁装置几何尺度、各层材料特性参数、外场振动特性参数、输出性能以及其他相关参数之间的一般性理论表达式。该研究成果可为压电薄膜性能分析和压电薄膜器件的设计提供较精确的理论分析依据。. 利用理论建模、实验测量与计算机模拟相结合的方法，验证了剪切模式压电薄膜悬臂梁装置模型的合理性，最终提出了一种简易且可准确测量压电薄膜剪切压电应变系数d15的实验方法。. 本项目着眼于解决压电薄膜领域的瓶颈问题，研究内容涉及压电薄膜材料和器件领域学术界关心的热点问题，且研究手段丰富多样，研究思路较新颖，具有普遍的科学意义。