Modified energy harvesting figures of merit for stress- and strain-driven piezoelectric systems
Modified energy harvesting figures of merit for stress- and strain-driven piezoelectric systems
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DOI：
10.1140/epjst/e2019-800143-7
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发表时间：
2019-08
期刊：
影响因子：
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通讯作者：
J. Roscow;H. Pearce;H. Khanbareh;S. Kar‐Narayan;C. Bowen
中科院分区：
文献类型：
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作者：
J. Roscow;H. Pearce;H. Khanbareh;S. Kar‐Narayan;C. Bowen
压电体是用于机械能量收集技术的一类重要材料。在本文中，我们评估的压电收获过程中，并定义的关键材料性能，应考虑有效的材料设计和选择。多孔压电陶瓷先前已被证明显示出改善的收获性能相比，其致密的同行由于介电常数的降低与引入的孔隙度。我们进一步考虑多孔压电陶瓷的机械顺应性增加的能量转换效率和输出电功率的影响，这一概念。有限元建模用于研究孔隙率对相关能量收集品质因数的影响。由于孔隙率的顺应性的增加被示出为增加在应力驱动条件下传输到系统中的机械能的量，以及应力驱动的品质因数FoM33X，尽管机电耦合系数减小。我们展示了了解压电能量采集器是应力驱动还是应变驱动的重要性，并演示了如何使用孔隙度来定制压电陶瓷采集器的电气和机械性能。最后，我们根据对压电收获过程中每个阶段的考虑以及系统是应力驱动（FijX）还是应变驱动（Fijx），推导出两个新的品质因数。
Piezoelectrics are an important class of materials for mechanical energy harvesting technologies. In this paper we evaluate the piezoelectric harvesting process and define the key material properties that should be considered for effective material design and selection. Porous piezoceramics have been shown previously to display improved harvesting properties compared to their dense counterparts due to the reduction in permittivity associated with the introduction of porosity. We further this concept by considering the effect of the increased mechanical compliance of porous piezoceramics on the energy conversion efficiency and output electrical power. Finite element modelling is used to investigate the effect of porosity on relevant energy harvesting figures of merit. The increase in compliance due to porosity is shown to increase both the amount of mechanical energy transmitted into the system under stress-driven conditions, and the stress-driven figure of merit, FoM33X, despite a reduction in the electromechanical coupling coefficient. We show the importance of understanding whether a piezoelectric energy harvester is stress- or strain-driven, and demonstrate how porosity can be used to tailor the electrical and mechanical properties of piezoceramic harvesters. Finally, we derive two new figures of merit based on the consideration of each stage in the piezoelectric harvesting process and whether the system is stress- (FijX), or strain-driven (Fijx).