Lightweight mechanical amplifiers for rolled dielectric elastomer actuators and their integration with bio-inspired wing flappers

摘要

Dielectric elastomer actuators (DEAs) are attractive for use to bio-inspired flapping-wing robots because they have high work density (specific energy) and can produce a large actuation strain. Although active membrane of dielectric elastomer is lightweight, the support structure that pre-tensions the elastomeric membrane is massive and it lowers the overall work density. If DEA was to be used successfully to drive the flapping-wing robots, its support structure must be as lightweight as possible. In this work, we designed, analyzed, and developed a lightweight shell using cross-ply laminate of carbon fibre reinforced polymer (CFRP) to pre-strain a rolled DEA. The CFRP shell was shown to weigh 24.3% of total mass for the whole DEA assembly while providing up to 35.0% axial pre-strain to a rolled DEA (BJB-5005 silicone rubber). This DEA assembly using the CFRP shell achieved 30.9% of the theoretical work density for BJB-TC5005 membrane at 33.5MV/m. In comparison, the spring rolls with a massive spring core were reported with overall work density merely 10-20% of the maximum value. Furthermore, this CFRP shell can amplify an axial DEA stroke into a larger transverse shell deformation. With these deformation characteristics, this CFRP shell and a rolled DEA were successfully integrated with an insect-inspired thoracic mechanism and they were shown feasible to drive it for flapping wing.