scholarly journals Effects of Off-Plane Deformation and Biased Bi-Axial Pre-Strains on a Planar Contractile Dielectric Elastomer Actuator

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 75
Author(s):  
Runan Zhang ◽  
Pejman Iravani ◽  
Patrick Keogh

Dielectric elastomers are in a special class of electro-active polymers known for generating expansion in plane and contraction in thickness under voltage application. This paper advances the understanding of a planar contractile dielectric elastomer actuator (cDEA) that is distinct from conventional multi-layer cDEAs but generates comparable contractile strains. Its structure has a rod-constrained rhombus-shaped electrode region, which undergoes simultaneous in-plane contraction and extension during actuation depending on the configuration of the rod-constraining. It is demonstrated that when the planar cDEA is driven by high voltages, off-plane deformation (i.e., wrinkling) in the direction of contraction causes the rod-constrained electrode region to lose tension and extend in the lateral direction, resulting in a significant increase in contraction strain. It also demonstrates that the contraction strain can be increased further by having biased bi-axial pre-strains. By incorporating both effects, the new cDEA generates a maximum contraction strain of 13%, twice that reported previously for planar cDEAs. A modified planar cDEA, having an additional rigid frame to maintain the pre-strain in the lateral direction to contraction was also developed to demonstrate contractile force actuation. Finally, a stability study shows that the planar cDEA has a primary failure mode of electrical breakdown close to the corners of the rod-constrained electrode region. Having inactive regions around the active cell is essential for generating contraction and eliminating buckling of the planar cDEA in the lateral direction.

2018 ◽  
Vol 29 (5) ◽  
pp. 998-1011 ◽  
Author(s):  
Hamza Edher ◽  
Louise Maupas ◽  
Sunraaj Nijjer ◽  
Armaghan Salehian

A common prophylaxis against peripheral vascular diseases utilizes pneumatic active compression systems. Although effective, traditional active compression systems require the use of an air compressor and pump and are, therefore, ill-suited for ambulatory use. The current work introduces a novel approach to developing an ambulatory smart material–based active compression system. The actuation system is composed of a belt-like mechanism connected in conjunction with a multi-layered dielectric elastomer actuator. The belt mechanism allows compression to be applied directly with voltage application. By doing so, the proposed design limits the period during which the actuator should be charged and improves system power efficiency and lifetime. An analytical model which defines the pre-compression exerted by the actuation system before voltage application is presented and validated experimentally. Experimental results for the belt mechanism characterization, dielectric elastomer actuator characterization and actuation system testing are presented. Through experimental testing, it is shown that the initial pre-compression can be fine-tuned by varying the parameters of the system as defined in the analytical model, and that the pre-compression has little effect on the consequent actuation output amplitudes.


2021 ◽  
pp. 112889
Author(s):  
Junxing Meng ◽  
Yu Qiu ◽  
Chengyi Hou ◽  
Qinghong Zhang ◽  
Yaogang Li ◽  
...  

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