Modelling and optimisation of Electro-Active Polymer (EAP) devices

摘要

The control of boundary layers either for skin-friction reduction or for udfight control can be achieved by their manipulation using deformable surfaces. In the case of theudformer, it is known that the manipulation of coherent structures in the turbulentudboundary layer can lead to significant drag reductions. However, the challenge is to find actuators and sensors that are functional at these spatial scales (10 micron to 0.1udmm) and the associated temporal scale (100 kHz). Electro-Active Polymers (EAPs)udprovide excellent performance, are light weight, flexible, and low cost. ThereforeudEAPs, and in particular Dielectric Elastomer Actuators (DEAs), provide many potentialudapplications as micro-actuators and micro-sensors.udModelling DEA devices is a cost-effective way of providing a better understandingudof the devices and optimising their designs. Acquiring a model for the EAP materialuditself is the first essential step in DEA modelling. A modelling technique takingudinto account the material non-linearities and its behaviour at large deformationsud(`hyperelasticity') is presented in the third chapter of this thesis. The main challengeudin modelling DEA devices is the modelling of their electro-mechanical coupling.udCommercially available electro-mechanical modelling does not apply to non-linearudmaterials such as EAPs. The ANSYS Finite Element (FE) software is the tool usedudin this work to develop a novel model presented in the fourth chapter. Variousudmeans of optimising the design of DEA devices are suggested in the sixth chapterudusing the developed DEA model. A novel design of an EAP-based pressure sensorudis suggested in the seventh chapter; FE modelling is used to study the abilities andudperformance of such a device. To complete the model, its time-dependent properties are examined by a modal analysis examined in an eighth chapter. The thesis is completed by examining the potential for DEA in providing a `smart' surface for distributed aerodynamic control.