| Popis: |
Dielectric elastomer actuators (DEAs) are compliant capacitors, which are able to transduce electrical into mechanical energy and vice versa. As they may be applied in different surrounding conditions and in applications with alternating excitations, it is necessary to investigate both, the thermal behavior and the in fluence of the temperature change during operation. Due to mechanical and electrical loss mechanisms during the energy transfer, the DEA is subjected to an intrinsic heating. In detail, the dielectric material, which has viscoelastic properties, shows a mechanical hysteresis under varying mechanical loads. This behavior leads to a viscoelastic loss of energy in the polymer layer, resulting in a heating of the structure. The non-ideal conduction of the electrode provokes a resistive loss when charging and discharging the electrode layer. Operation with frequencies in the kilohertz-range leads to remarkable local heat dissipation. The viscoelastic material behavior and the resistivity are assumed to be dependent on the temperature and/or on the strain of the material. By this, a back-coupling from the thermal field to the mechanical field or the electrical field is observed. In order to provide a thermal equilibrium, also the convective cooling { the structure is subjected to { has to be considered. Depending on the frequency and the type of electrical driving signal and mechanical load, viscoelastic and resistive heating provide different contributions during the dynamic process. In the present study we capture the described effects within our modeling approach. For a given dielectric elastomer actuator, numerical investigations are performed for a given electrical load. |
