摘 要

压电纤维复合材料（MFC，Macro Fiber Composite）具有压电陶瓷的压电性能，并且拥有聚合物的柔韧性，克服了传统压电陶瓷脆性大、各向异性差、声阻抗较大等缺点，在民用和军事领域都有着广泛的应用，尤其在俘能领域中，它的低频带宽大和高输出电压越来越引起科研工作者的关注。

本文通过切割叠层法制备MFC，并以优化悬臂梁结构的方式设计MFC俘能器，研究俘能器结构设计与其电输出性能的关系，对MFC俘能器的发展给出一定的指导。主要研究内容如下：

1. 以PZT-5H陶瓷为主要原料，采用切割-叠层法制备MFC压电纤维复合材料，优化封装、极化工艺。金相显微镜观察发现，压电纤维复合材料上、下电极呈对称分布，与纤维接触紧密，叉指电极与压电纤维之间环氧树脂粘接层厚度很薄，直接作用在压电纤维上的电场较大，保证了压电纤维在极化时极化更充分。随着外加电压升高，电滞回线趋于饱和，矫顽场和剩余极化电荷增加，铁电性能较好。
2. 设计MFC悬臂梁俘能器，研究基底材料、形状、长度，厚度对俘能器电输出性能的影响。不同的基底材料、形状、长度、厚度会改变悬臂梁俘能器的弹性模量E、截面惯性矩I、密度ρ和横截面积A，从而影响其电输出性能。在黄铜板、铝板、碳纤维板三种不同的基底材料中，黄铜板的输出电压最高，谐振频率较低，表现出较好的电输出性能。与矩形、三角形、短边梯形相比，长边梯形基底输出电压最高，谐振频率较低。基底长度从7.5 cm增加至10.0 cm，谐振频率降低35.2%，输出电压提高了40.8%。基底厚度为0.3 mm时输出电压最高，比厚度为0.4 mm的输出电压提高了76.9%，谐振频率和半高宽均介于其它两个厚度比之间。
3. 研究了MFC粘贴位置、末端质量对悬臂梁俘能器电输出性能的影响。增加MFC粘贴位置与固定端距离会导致输出电压大幅度降低。当距离从0 cm增加至2.5 cm时，从13.8 V降低至4.8 V，降低了65.2%，对谐振频率的影响程度相对较小。比较无末端质量与0.6 g末端质量两种情况，在附加0.6 g末端质量后，输出电压仍保持为13.8 V，谐振频率向低频方向移动，从20.6 Hz减小至16.2 Hz，减小了21.4%。MFC粘贴于固定端，输出电压最大；在一定范围内附加末端质量，能够在保持输出电压较高的同时，使谐振频率向低频方向移动。

关键词：压电纤维复合材料；悬臂梁；俘能器；电输出性能

Abstract

Compared with the traditional piezoelectric ceramics, the macro fiber composites (MFC) are characterized by their flexibility on large deformation and piezoelectric properties, which overcome the brittleness, poor anisotropy, large acoustic impedance and other defects of traditional piezoelectric ceramics. More and more attention has been paid to MFC because of their large bandwidth at low frequency and high output voltage.

In this paper, macro fiber composites were successfully fabricated by the cutting-stacking method. A cantilever beam-type energy harvesting device with MFC was designed by optimizing the structure. The relationship between the electric output performance and structure of the harvester was studied. The principal works of this paper and corresponding conclusions are as follows.

1. Macro fiber composites were successfully prepared by the cutting-stacking method by PZT-5H ceramics as main raw materials, and the process of encapsulation and polarization were optimized. The microstructures of MFC were characterized by metallographic microscope. The results exhibited the preferable coupling among the fibers, epoxy and interdigitated electrodes. And good alignment between the top and bottom electrodes was clearly found which confirmed that the piezoelectric fibers were fully polarized. With the increasing of voltage, the hysteresis loop tended to be saturated, as well as the coercive field. And the remnant polarization charge increased which showed the excellent ferroelectric performance of MFC device.
2. The influences of the material, shape, length, the thickness of substrate on the electric output performance of harvester were investigated. Among the substrate materials of brass, aluminum and carbon fiber, the output voltage of brass substrate was the highest and the resonant frequency of it was much lower. Compared with the rectangular, triangular and short-side trapezoidal, the output voltage of the long-side trapezoidal harvester was the highest one, as well as the low resonant frequency, which has the function of distributing the strain more evenly at every point of the surface on the beam. When the length of substrate increased from 7.5 cm to 10.0 cm, the resonant frequency was reduced by 35.2%, and the output voltage was increased by 40.8%. The output voltage of harvester was the highest one when the thickness of substrate was 0.3 mm. In conclusion, when the beam parameters were brass (material), long-side trapezoidal geometry (shape), 10.0 cm (length) and 0.3 mm (thickness), the cantilever beam-type energy harvester with MFC represented low resonant frequency and the highest output voltage.
3. The influences of sticking position of MFC and the tip mass on the electric output performance of the cantilever beam harvester were studied. The output voltage decreased by 62.5%, from 13.8 V to 4.8 V, while increasing the distance between sticking position and the fixed end. The influence on the resonant frequency was relatively small. The output voltage remained at 13.8 V after adding the 0.6g tip mass, and the resonant frequency shifted from 20.6 Hz to 16.2 Hz, deceasing by 21.4%. Therefore, when MFC pasted at the fixed end, the harvester represented the maximum output voltage. It was possible to reduce the resonant frequency as well as maintaining the output voltage at a high level by adding the tip mass in a certain range.

Key Words：macro fiber composites; cantilever beam; energy harvester; electric output performance

目 录

第1章 绪论 1

1.1引言 1

1.2压电纤维复合材料 1

1.2.1主动型纤维复合材料（AFC） 2

1.2.2粗纤维复合材料（MFC） 2

1.3压电式俘能器研究进展 3

1.3.1圆形结构压电式俘能器研究进展 3

1.3.2悬臂梁结构压电式俘能器研究进展 4

1.4压电式俘能器应用实例 5

1.4.1可植入式设备 5

1.4.2流体流动能量收集 6

1.4.3微机电系统能量收集 6

1.5研究内容及目的 6

第2章 MFC压电纤维复合材料的制备及性能表征 7

2.1实验原材料及仪器 7

2.2 MFC压电纤维复合材料的制备 8

2.2.1切割-叠层法制备压电纤维复合层 8

2.2.2 MFC压电纤维复合材料的封装 8

2.2.3 MFC压电纤维复合材料的极化 9

2.3 MFC压电纤维复合材料的性能表征 9

2.3.1形貌结构表征 9

2.3.2介电性能表征 10

2.3.3铁电性能表征 11

第3章 MFC悬臂梁俘能器的制作及电输出性能表征 13

3.1 MFC悬臂梁俘能器的制作 13

3.2 MFC悬臂梁俘能器的电输出性能实验测试 13

3.3 MFC悬臂梁俘能器对激振源的响应 14

3.3.1 MFC悬臂梁俘能器对激振频率的响应 14

3.3.2 MFC悬臂梁俘能器对激振力的响应 14

3.4能量转换结构物理模型和Euler-Bernoulli梁模型 15

3.4.1能量转换结构物理模型 15

3.4.2 Euler-Bernoulli梁模型 16

3.5基底对MFC悬臂梁俘能器电输出性能的影响 17

3.5.1基底材料对俘能器电输出性能的影响 17

3.5.2基底形状对俘能器电输出性能的影响 18

3.5.3基底长度对俘能器电输出性能的影响 20