Reduced Model and Application of Inflating Circular Diaphragm Dielectric Elastomer Generators for Wave Energy Harvesting

Abstract

Dielectric elastomers (DE) are incompressible rubberlike solids whose electrical and structural responses are highly nonlinear and strongly coupled. Thanks to their coupled electromechanical response, intrinsic lightness, easy manufacturability, and lowcost, DEs are perfectly suited for the development of novel solidstate polymeric energy conversion units with capacitive nature and highvoltage operation, which are more resilient, lightweight, integrated, economic, and disposable than traditional generators based on conventional electromagnetic technology. Inflated circular diaphragm dielectric elastomer generators (ICDDEG) are a special embodiment of polymeric transducer that can be used to convert pneumatic energy into usable electricity. Potential application of ICDDEG is as power takeoff system for wave energy converters (WEC) based on the oscillating water column (OWC) principle. This paper presents a reduced, yet accurate, dynamic model for ICDDEG that features one kinematic degree of freedom and which accounts for DE viscoelasticity. The model is computationally simple and can be easily integrated into existing wavetowire models of OWCs to be used for fast analysis and realtime applications. For demonstration purposes, integration of the considered ICDDEG model with a lumpedparameter hydrodynamic model of a realistic OWC is also presented along with a simulation case study.