【作者】 彭瀚旻；

【导师】 赵淳生；

【作者基本信息】 南京航空航天大学 ， 机械电子工程， 2010， 博士

【摘要】 离子聚合物金属复合物(简称IPMC)是一种新型智能材料,属于电活性聚合物(EAP)范畴,在电压激励下可以产生大变形。它具有驱动电压低、变形大、无噪音、推重比大和柔顺等特点,非常适用于微机械、微电子以及微控制系统;目前,已经成为世界微小型驱动器和传感器的研究热点之一。同时,为达到增大传递效率,简化驱动机构,减小结构尺寸以及提高系统可靠性的目的,其研究目标也向小型化、精细化、灵巧化、柔顺化、知性化等方面发展。虽然IPMC具有以上优点,但是其电响应性能不稳定,材料的电激励机理不完善,导致其应用还主要停留在实验室测试阶段。为提高IPMC薄膜电响应性能,本文围绕其电响应特性进行了详细的研究,内容涵盖材料的制备、改性、建模、实验和应用。本文的主要研究工作如下:(1)制备了Pt电极型IPMC薄膜;测量了其水溶胀特性、电致变形特性、力学输出特性。同时,改造后的网格Pt电极型IPMC薄膜在5min内(传统IPMC薄膜工作30s内会发生回弹)没有发生回弹现象,提高了IPMC材料的电响应的稳定性。(2)发现了Pt电极型IPMC薄膜具有根部弯曲的非线性大变形现象。其自由段即使在无电压激励的情况下,根部在电激励下的变形就可以导致其末端大变形。本文着重研究了此类IPMC的电激励模型,分析了其内部物理变化规律;基于Nemat-Nasser的耦合分析并利用能量守恒定律,推导出集电学、化学、力学和流体的四场耦合IPMC电响应模型,仿真精度提高到13%(传统Nemat-Nasser模型对本文中IPMC计算误差为72%)。(3)针对三种IPMC薄膜进行了驱动性能仿真计算,模拟出材料根部和自由段内含水量、内部应力和应变、杨氏模量等关键性能参数的变化规律以及其随激励时间的非线性变化规律;求解出IPMC薄膜末端位移响应与其关键参数之间的关系;最终仿真出IPMC薄膜末端变形随时间变化的关系。实验结果与仿真结果一致性较好,验证了含根部弯曲非线性变形仿真模型的合理性、可靠性和有效性。(4)实验发现了IPMC电响应性能(变形、应力和应变)在启动时的三种非线性现象,对其分别进行了仿真计算。仿真结果与实验显示:在启动阶段中,上述三个性能参数与激励电压的关系曲线都近似为指数递增模式,而稳态阶段应力和应变仍然为指数递增模式,但变形却可以近似为线性递增关系。通过设计了薄膜电激励测试实验,验证了导致上述现象的原因来源于材料自身的充电效应。(5)开发了三款简易的IPMC手爪,它们具有耗能小、结构简单、柔顺、安静、体积小、推重比大等特点,驱动部件IPMC材料的柔性使其适用于抓取高精度表面的零件。本课题由国家自然科学基金面上项目《基于人工肌肉的直线型电机的探索性研究》(50407004)和面上项目《新型IPMC人工肌肉五指灵巧手的研究》(50875123)资助。更多还原

【Abstract】 Ionic polymer-metal composite (IPMC) is a new type of smart materials, which belongs to one class of electroactive polymers, and it can generate large deformation within voltage. The merits of IPMC are low driving voltage, large deformation, noiselessness, big thrust-weight ratio and flexibility, so it is extremely suitable for micro electronic mechanical system (MEMS); now it becomes one of central research issues as a small actuator or sensor all over the world. Further, to increase the transmission efficiency, simplify the drive mechanism, reduce the structure size and improve system reliability, the research goals are making IPMC materials becoming smaller, more fine, smarter, more flexible, and more intelligence.Although IPMC has above advantages, the electrical response properties are of instability and its corresponding drive mechanism is imperfect, inducing that most of its applications remain in the laboratory testing stage. For improving the performance of IPMC actuator, this dissertation will focus on the electrical response characteristics, covering IPMC fabrication, modification, modeling, experiments and applications. The main research contents are as follows:(1) IPMC membrane with platinum was fabricated; in order to obtain its water swelling properties, deformation characteristics under electrical stimulation, and mechanical output characteristics, all of them are measured. Further, the grid-based IPMC film with platinum was fabricated for overcoming the relaxation phenomenon of general IPMC material, the former can hold deformation at least 5 minutes without relaxation (general IPMC film occurred relaxation within 30 seconds). Therefore, this new type IPMC can improve the stability of IPMC electrical response.(2) It was found that within voltage excitation the general IPMC strips with platinum had nonlinear large deformation in its root. Even in the absence of electrical power in its free part, its tip deformation could also achieve large deformation just resulting from the root electrical response deformation. This dissertation concentrates on this kind of electrical excitation model for simulating and explaining the above phenomenon and analyzing the internal physical changes of IPMC. Based on Nemat-Nasser coupling model, energy conservation law is utilized to derive an improved simulation model by considering electrical, chemical, mechanical and fluid fields together. The results showed a large improvement for simulation accuracy up to 13% (original Nemat-Nasser model’s error for this kind of IPMC is 72%).(3) As to three IPMC membranes with different performance, their electrical response simulation had been completed. Both in root and free parts of IPMC strip, the changing principle of the water uptake, the internal stress and strain, Young’s modulus and other key performance parameters had been calculated and simulated, and the results showed strong nonlinear relationships; finally the nonlinear relationship between the IPMC tip displacement response and time was solved. The experimental and simulation results are in good agreement, and so it can verify that the above model is reasonable, reliable and validity.(4) Three performance parameters (deformation, stress and strain) nonlinear changes of IPMC strips were found in the start-up state, and their simulation results were carried out. In the start-up state, the relationships between these three performance parameters and their excitation voltages were approximately exponential increase trends; in stable state the stress and strain followed the exponential increase trend, but the deformation became an approximate linear increasing relationship. Then, by designing the test of IPMC electrical actuation, it can be testified that the reason leading to the above phenomena are charging effects from the IPMC material itself.(5) Three IPMC grippers with simple structures were designed and fabricated. The advantages of them are low energy consumption, simple structure, flexible, quiet, small size, big thrust-weight ratio, etc., and especially for the parts with high accuracy surface the IPMC materials could not damage the surface finish.This research activity is funded by National Natural Science Foundation of China General Programs (Grant No.50407004 and Grant No.50875123).更多还原