Influence of stretch and temperature on the energy density of dielectric elastomer generators

Abstract

Application of dielectric elastomers (DE) has remarkably increased in mechatronics because they are suitable candidates for energy harvesting due to their low cost, light weight, and high energy density. The dielectric elastomer generators (DEGs) exhibit high performance regardless of the applications scale. However, functioning as a generator, a DE may lose its efficiency due to several failure modes including material rupture, loss of tension (LT), electrical breakdown (EB), and electromechanical instability (EMI). The failure modes confine the area of allowable states for generation process. Dielectric constant and dielectric strength of such elastomers depend on the amount of applied deformation and also working temperature, which are often ignored in theoretical simulations. In this paper, variations of the above-mentioned parameters are considered in mechanical and electrical modellings to investigate their effects on energy density and efficiency of generators. Obtained results show that, ignoring the variations of material dielectric constant and dielectric strength leads to overestimation of the specific energy. Furthermore, it is shown that, for an acrylic-based generator, the specific energy sharply decreases with temperature rise.