摘 要

在一定条件下，水在流动的过程中会产生涡旋，因此引起一定程度的振动，这些振动产生的能量可以收集起来实现水中低功耗的电子设备自供能，满足其长时间工作的要求。要在水流中实现涡激俘能，要求工作器件具有较好的应变性能、压电性能以及较好的低频响应。压电纤维复合材料(Macro Fiber Composite，简称MFC)不仅具有较好的压电性能，又具有相当的应变性能，同时具有突出的单向性能，并且对低频具有较好的响应，因此可以用来收集涡激振动能量。

限制压电陶瓷产生更高功率的主要原因就是其固有的高介电损耗，PMnS压电陶瓷比传统的PZT压电陶瓷有更低的介电损耗，制备以其为功能相的MFC来进行涡激振动能量收集可以提高器件的输出功率。

本文主要的研究工作和结论如下：

首先，制备了PMnS压电陶瓷，并对其进行了结构及形貌表征，测试了主要的电学性能参数，压电常数d₃₃为300；介电损耗为0.8656％，比市场上的PZT-5H低50％以上；除此以外还对PMnS压电陶瓷进行了场致应变曲线(S-E曲线)和极化曲线(P-E曲线)测试，证明了所制备的压电陶瓷具有良好的应变性能和铁电性能。

然后，利用切割填充法制备了MFC，并对制备过程进行了详细的介绍，制备所得器件尺寸为60mm×10mm。对制备的MFC进行场致应变曲线(S-E曲线)和极化曲线(P-E曲线)测试，发现应变随着加载电压的增加而增加，具有良好的应变响应，并且当加载电压为2000V时，纵向达到了378 pC/N。

最后，制作了压电悬臂梁(以尺寸为20mm×90mm×0.2mm的铝板为基底，将MFC负载在上面)测试了其固有频率为21.8Hz；通过测试得到了标准能量收集电路的最佳负载为200KΩ，同时证明了基于PMnS制备的MFC在理想振动条件下可以输出微瓦级别的功率，并且发现激振力越大，输出电压越高，在不损坏MFC的情况下，交流输出幅值可以稳定在9V以上。搭建了简易的涡激俘能平台，并在最佳负载下利用标准能量收集电路对MFC的俘能性能进行了实际测量，交流输出电压幅值为80mV,负载两端检测到的直流电压为25mV，最大测试功率为3.125nW。为了优化测试条件，本文设计了一个可以保证水流均匀且流速可控的水循环系统，以期在后续研究中获得更好的俘能性能。

关键词：涡激俘能；压电纤维复合材料(MFC)；PMnS

Abstract

Under certain conditions, vortices will be generated in the process of water flow, thus causing a certain degree of vibration. The energy generated by these vibrations can be collected to realize the self-power supply of low-power electronic equipment in water and meet the requirements of long time work. In order to realize vortex-induced energy capture in water flow, the working devices must have good strain performance, piezoelectric performance and low frequency response. Macro Fiber Composite (MFC) not only has good piezoelectric performance, but also has considerable strain performance, prominent unidirectional performance and good response to low frequency, so it can be used to collect vortex-induced vibration energy.

The main reason which limits the higher power generated by piezoelectric ceramics is its inherent high dielectric loss. PMnS piezoelectric ceramics have lower dielectric loss than traditional PZT piezoelectric ceramics, therefore the MFC based on PMnS piezoelectric ceramics can reach higher output power in vorticity induced vibration energy collection.

The main research work and conclusions of this paper are as follows:

Firstly, PMnS piezoelectric ceramics were prepared, and their structure and morphology were characterized. The main electrical performance parameters were tested. The piezoelectric constant d₃₃ was 300. The dielectric loss was 0.8656%, 50% lower than the PZT-5H in the market. In addition, the field strain curve (S-E curve) and polarization curve (P-E curve) of PMnS piezoelectric ceramics were tested, and it was proved that the piezoelectric ceramics had good strain and ferroelectric properties.

Then, MFC was prepared by cutting and filling method, and the preparation process was introduced in detail. The size of the prepared device was 60mm10mm. The field strain curve (S-E curve)and polarization curve (P-E curve) of piezoelectric fiber composites (MFC) were tested,and we found that the strain increases as the load voltage increases, which proves the MFC has good strain ability, and when the load voltage is 2000 v, longitudinal can reach 378 pC/N.

Finally, the piezoelectric cantilever beam (aluminum plate with a size of 20mm90mm0.2mm as the base and MFC load on it) was made and its natural frequency was tested at 21.8hz. The best load for the standard energy collecting circuit is tested ,which is 200 K Ω. In the meantime ,the ability of prepared MFC to output the μW level of power was proved in ideal vibration conditions. What is more, in the case of no damage to the MFC, the greater the vibration force is ,the higher the output voltage is, and AC output amplitude can be over 9 V stably. A simple vortex capture energy platform was built, and the standard energy collection circuit was used to measure the capture energy performance of MFC under the optimal load. The AC output voltage was 80mV, the DC voltage detected at both ends of the load was 25mV, and the maximum test power was 3.125nW. In order to optimize the test conditions and obtain better capture energy performance in the follow-up research, this paper designs a water circulation system which can ensure the water flow is uniform and the flow rate is controllable.

Key Words：Vortex-induced energy; Piezoelectric fiber composite (MFC); PMnS;

目 录

摘 要 I

Abstract II

第1章 绪论 1

1.1 引言 1

1.2 压电纤维复合材料 1

1.3 压电材料在水中采集能量的现状 2

1.4 论文研究意义及内容 4

第2章 PMnS压电陶瓷和压电纤维复合材料的制备及表征 6

2.1 制备 6

2.1.1 PMnS压电陶瓷的制备 6

2.1.2 压电纤维复合材料的制备 7

2.2表征 9

2.2.1 PMnS压电陶瓷的结构与电性能表征 9

2.2.2 压电纤维复合材料的结构与性能表征 10

2.3 本章小结 11

第3章 压电陶瓷及压电纤维复合材料电性能的研究 12

3.1 PMnS压电陶瓷结构与性能分析 12

3.1.1 结构分析 12

3.1.2电性能分析 13

3.2 压电纤维复合材料的性能研究 15

3.2.1 结构分析 15

3.2.2 铁电响应 16

3.2.3 压电性能 16

3.3 本章小结 17

第4章 俘能平台搭建及俘能测试 19

4.1 涡激俘能组件的设计与测试 19

4.1.1 压电悬臂梁 19

4.1.2 能量收集电路 21

4.1.3 阻流体 22

4.2 涡激俘能平台的搭建 23

4.3 结果与分析 23

4.4 本章小结 24

第5章 结论及展望 26

5.1 结论 26

5.2 展望 26

参考文献 28

致 谢 30

第1章 绪论

1.1 引言

随着微电子器件的体积不断变小，能耗也越来越低^[1]，然而,这些电子系统仍然需要电池或电缆供电，这增加了器件重量，也增加了常规维护或更换成本。另一方面，利用能量收集技术直接从环境中收集少量能量从而实现给微电子器件供能已经成为一种潜在的自供电解决方案。其中，振动能量收集技术可用于将环境振动能量转换为用于集成传感器和电子设备的有用电能。

在振动能量收集领域中，较为常用的是压电陶瓷。但是由于陶瓷本身固有的脆性大、硬度高、不易变形等特点，压电陶瓷材料的应用受到了很大的限制。尤其是在曲面、柔性或轻质结构中的应用。

1.2 压电纤维复合材料

压电纤维复合材料是指单向的压电陶瓷纤维依靠平行排列的聚合物连结在一起，并用叉指电极封装而成的一种复合材料^[2,3]。与传统压电陶瓷材料相比，压电纤维复合材料具有较好的相容性和柔韧性，其极化和驱动电压更低，同时压电纤维尺寸分布便于控制，且具有各向异性驱动的特性。这些特性使压电纤维复合材料在多领域得到广泛的应用，例如结构健康监测^[4]、驱动^[5]、能量收集^[6]、主动/被动振动抑振^[7]等。美国麻省理工学院Bent等人^[2]首先设计出了第一代压电陶瓷纤维复合材料(Active Fiber Composite，简称AFC)。AFC由圆柱形的压电纤维、聚合物以及叉指电极组成，这种压电陶瓷纤维复合材料其既保留了压电晶体材料的压电特性以及高灵敏度和高频率响应等优点，又克服了压电晶体材料脆性大和柔韧性差等不足。因此在驱动以及传感领域得到了广泛关注，在应用上也取得了巨大成功。但是由于其压电纤维的圆柱形设计导致制备成本高与应用受限等不足，因此，美国国家航空和宇宙航行局—兰利研究中心的研究者^[8]开发出了新一代的压电纤维复合材料(Macro Fiber Composite，简称MFC)，MFC采用矩形截面压电纤维陶瓷，简化了加工过程，同时也提高了材料本身的应变性能。这种压电纤维复合材料首先被应用于弯曲表面的传感器，如飞行器机翼等^[9]。Anton等^[10]还试图利用压电陶瓷纤维复合材料实现对微型无人飞机电能的供能。

需要注意的是，由于MFC兼具了另外两种压电俘能材料——锆钛酸铅压电陶瓷(PZT)、聚偏二氟乙烯(PVDF)两者的优点，既保持了较高的机电耦合系数和能量转换效率，又具有一定的柔性，可以实现较大的形变，因此在振动能量收集方面有独特的优势。