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Title: Investigation into a multilayered elastomer EAP bending actuator fabricated using a novel spray deposition method
Author: Araromi, Oluwaseun A.
ISNI:       0000 0004 2725 4844
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2012
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This thesis presents an investigation into the fabrication, modelling and optimisation of multi- layered unimorph (bending) EAP dielectric elastomer actuators. Fabrication of dielectric elastomer (DE) EAPs is non-trivial as it requires the production of very thin dielectric films «100 urn) to maximise performance for a given input voltage, and flexible conductive electrodes. A novel dielectric elastomer actuator (DEA) fabrication method based on spray deposition is presented. The characterisation and optimisation of this technique are described and fabrication of very thin DE films « 40 urn) with high accuracy demonstrated. The fabrication method is relatively simple and inexpensive compared to com- peting methods, and is readily adaptable for full automation for mass production of DEAs. Multilayer DEAs are difficult to fabricate due to the need for electrical connection of the DE layers. The fabrication of multilayered unimorph DEAs (MUDEAs) using spray deposition is presented, good repeatability and reliability (- 80% success rate) are demonstrated. The MUDEAs exhibit large tip deflections (- 19 mm) and resonant operation with substantial strain amplification (- 1000%) is achieved. The fabricated actuators are also used to develop proof- of-concept wing flapping designs for MA V applications capable of simultaneous flapping and (minimal) pitching. Models of MUDEAs are important for producing optimal actuator designs. Current model- ling approaches presented in the literature are inadequate for multilayer DEA configurations with non-uniform geometries. A novel finite element (FE) approach for modelling MUDEAs is presented. The model is used to simulate the deflection of two, three and four layer MU- DEAs with inhomogeneous layer geometries. The results are validated against experiments and show good agreement with the data. The Maxwell stress in MUDEAs is also derived and shown to be the same as that for an unconstrained (i.e. free standing, with no external forces or loads applied) DEA. The validated 3D FEA model is used to investigate the effects of varying the number of layers on MUDEA deflection, for several DE layer thicknesses and substrate materials. The results show that there is an optimum number of layers for which MUDEA tip deflection is. a maximum and that it is more beneficial to use actuators with thinner DE layers, rather than thicker layers, for a given combined DE layer thickness.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available