Energy Harvesting Theory Research And Device Design Based On Dielectric Elastomer Smart Soft Materials

For a long time, research on materials mostly concentrated on the field of hardmaterials. But with the development of society, the traditional hard materials alreadycan not meet the needs of a lot of social production and daily life. As we know, themain structure of animals, plants and other organisms in the natural world aremostly soft materials. Compared with the traditional metal, ceramic and some otherhard materials, soft materials reflect great advantages. Dielectric elastomer belongsto a typical soft material which has a large deformation, light weight, high responserates, high elastic energy density, low cost, easy processing and goodbio-compatibility and other advantages. The study of dielectric elastomer started bythe Stanford Research Institute from the1990s. It is able to produce largedeformation under mechanical force and electric field, so that it can achieve mutualconversion between mechanical energy and electrical energy. Based on this property,dielectric elastomer is widely used in producing different kinds of actuators, sensorsand generators, and it has great prospects in mechanical, medical, military,aerospace and other fields.In this thesis, the energy harvesting theory of dielectric elastomer and itsapplication device have been studied based on the property of the conversion frommechanical energy to electrical energy. Firstly, from the perspective of soft materialmechanics, we explained the dielectric elastomer theory based on thethermodynamical framework and continuum mechanics model, then analysed theinfluence of constitutive relations under different superelastic model(Gent andNeo-Hookean) based on theoretical and experimental study. Secondly, we deducedthe equations based on the five failure modes of dielectric elastomer and depictedallowable areas in force-displacement and voltage-charge plane, then calculated thetheoretical maximum conversion energy and the achievable maximum conversionenergy under the force-displacement plane and the voltage-charge plane,respectively. Thirdly, we analysed the energy dissipation in energy harvestingprocess, taking into account two conditions: viscoelastic and leakage current, inwhich the viscoelastic can lose the input mechanical energy and the leakage currentcan lose the output electrical energy. They are both the major factors of the energydissipation. Finally, we designed and assembled an energy harvesting device whichcan take advantage of the waves to compress the dielectric elastomer in order toconverts mechanical energy into electrical energy. The device can light severaldiodes through a designed energy harvesting circuit, so we can visually observe theconverted electrical energy; then we measured and calculated the output electrical energy and compared it with the theoretical value.