介电弹性体动态换能机理及能量收集系统设计方法研究

Dielectric elastomer (DE), a new type of functional material belonging to the family of so-called Electroactive Polymers (EAPs), has a variety of advantages such as good flexibility, large deformation, high energy density, and strong environmental adaptability. It also can convert the mechanical strain energy into electrical energy with an efficiency as high as 80%~90%, and therefore has broad application prospects in the emerging field of energy harvesting. However, due to the lack of understanding for the DE-based energy harvesting process as well as the key factors affecting its dynamic characteristics, the current research can not accurately explain the complex behavioral mechanisms of such a cyclic system, and consequently can't guide the practical design effectively. This situation undoubtedly restricts the material performance advantages to a great extent. In view of this, the dynamic viscoelasticity of the material, which is closely related with the kinematic variables of Stretching ratio and stretch rate, will be taken into account in this project. Starting from the basic mechanical and electrical properties of the material, the nonlinear coupling behavior between the large-deformation flexible structure and the electrostatic field will be studied at first. Based on this, a multi-domain dynamic model to describe the cyclic energy-conversion behaviors of such a mechanical-electrical-thermal coupling system will be constructed gradually, from the film to the device structure, and until to the whole system. Through the above work, we will be able to conduct an in-depth study on the mechanism of the interaction and synergistic effects between the DE structural, the control circuit, and external environment, and to reveal the principles of the energy transfer, conversion and loss in energy harvesting processes. It is expected that the research of this project could provide a necessary and reliable theoretical basis for analysis and design of the practical high-performance DE-based energy harvesting devices/systems.

介电弹性体(Dielectric elastomers，DE)是一种新型电活性功能材料，具有柔性好、变形大、能量密度高等多种优点，并能以高达80%~90%的效率，将机械应变能转换为电能，因而在面向人体及自然界的能量收集领域具有广阔的应用前景。然而，现有的研究由于对DE能量收集的工作特点及体现其动态特性的关键因素认识不够，以致不能准确揭示此循环换能体系在多因素综合作用下的复杂行为机制并有效指导实际设计，在很大程度上制约了材料性能优势的发挥。本项目拟以DE材料在动态条件下的粘滞耗能特性及其非线性力电耦合行为为基础，通过逐层构建机-电-热多域耦合系统循环换能的理论模型，深入研究大变形柔性DE结构与电路及外部环境间交互、协同的作用机制，旨在阐明其中能量传递、转换与损耗的特性与规律，形成高性能DE能量收集系统一体化设计、优化及控制的策略与方法，为实际系统/装置的分析设计提供必要而可靠的理论依据。

项目紧扣研究目标，从介电弹性体在循环拉伸—收缩过程中的动态粘弹性耗能特性出发，开展了材料在能量收集过程中大变形、非线性力电耦合及换能行为的基础研究和高性能能量收集系统的设计研究。重点内容和主要进展有：（1）分别基于广义Kelvin-Voigt 流变模型和准线性粘弹性模型，构建了两种不同形式的介电弹性体非线性大变形粘—超弹性本构模型，定量揭示了材料在拉伸率和拉伸速率共同影响下的迟滞耗能行为机理；（2）建立了描述介电弹性体粘性能量耗散特性并适用于工程计算的线形阻尼模型，开展了能量收集策略及方案的对比研究，探讨了不同边界条件和加载方式下的DEG的能量回收能力；（3）开展了新型DEG结构和能量收集电路的协同设计研究，提出了一种形式简单，可摆脱对外部偏置电源的周期性依赖，直接为负载供电的“自循环”电路模型。进一步基于软体结构“对抗式”设计思想和混合电极材料电阻随变形而变化的特性，提出了一种集成软体DEG和调理电路的“全软体”系统原型；（4）对提出的电路和结构进行了基础实验，验证了其可行性；并基于自循环电路和环形DEG开展了多因素正交试验，探究了偏置电压、拉伸位移、频率、预拉伸比、负载电阻等参数对能量收集性能产生的影响；结合仿真实验，开展了系统的协同设计和全局优化研究。.项目研究较好地达成了预期目标，取得了并有望继续取得具有创新性和工程应用价值的研究成果，可为实际DE能量收集系统的分析设计，提供有益的科学基础和方法借鉴。