介电弹性体材料致动器的非线性动态行为研究

介电弹性体材料(Dielectric Elastomer,简称DE),是制造柔性智能致动器最有潜力的电活性聚合物(Electroactive polymer,缩写EAP)材料之一,可在电压驱动下产生大幅度的厚度与面积变形,最大面积应变高达1600%.由于DE材料的固有阻尼特性,从而使其变形具有时间依赖性,因此动态变形中,其能量转换、宏观变形等特性也必然受到阻尼的影响.借助热力学自由能理论,考虑DE材料致动器面内动态变形过程中的惯性力和阻尼力,构建平面DE材料致动器的非线性动力学模型.研究了交变电载荷下DE系统的非线性动态特性,包括其幅频曲线、位移响应和相平面图.研究表明,存在阻尼的时候,DE系统的振动会随着时间的增加出现锁频现象,最后变成一种具有恒定振幅的振动.相平面图和Poincaré映射图研究表明,考虑阻尼后DE系统的稳态相平面图是一条闭合的曲线,其Poincaré映射点集是有限的,代表其产生周期性运动.研究成果为DE材料致动器在各种动态驱动器或传感器中的应用提供理论依据.

Nonlinear dynamic performance of a dielectric elastomer actuator

Dielectric elastomers (DE) are one of the most potential electro-active polymer (EAP) used as high-performance actuators.A DE subjected to a voltage can generate large thickness and area expansion with a maximum area strain of 1600％.As DE has natural damping properties and its deformation is then dependent to time,its dynamic performance,energy conversion and large deformation are definitely influenced by damping.A free energy model is developed to study the dynamic characteristics of a dielectric elastomer actuator undergoing inplane deformation subjected to the combined loadings of a mechanical press and an electric field.The numerical results including the oscillation,phase diagrams and Poincaré maps are presented to show the influence of the damping on the nonlinear dynamic characteristics of the dielectric elastomer.The numerical results indicate that the damping effect could cause the dynamic responses to constant vibration and decrease the amplitude.The phase paths are all presented in closed regions and the points of Poincaré map are finite,indicating that the DE system experiences a nonlinear periodic oscillation,and the dynamic oscillation of the DE system is stable.These conclusions provide the basis for the exploration of high-performance dielectric elastomers under dynamic mechanical and electrical loads.