On the dynamic electromechanical loading of dielectric elastomer membranes

Abstract Dielectric elastomer actuators (DEAs) have received considerable attention recently due to large voltage-induced strains, which can be over 100%. Previously, a large deformation quasi-static model that describes the out-of-plane deformations of clamped diaphragms was derived. The numerical model results compare well with quasi-static experimental results for the same configuration. With relevance to dynamic applications, the time-varying response of initially planar dielectric elastomer membranes configured for out-of-plane deformations has not been reported until now. In this paper, an experimental investigation and analysis of the dynamic response of a dielectric elastomer membrane is reported. The experiments were conducted with prestretched DEAs fabricated from 0.5 mm thick polyacrylate films and carbon grease electrodes. The experiments covered the electromechanical spectrum by investigating membrane response due to (i) a time-varying voltage input and (ii) a time-varying pressure input, resulting in a combined electromechanical loading state in both cases. For the time-varying voltage experiments, the membrane had a prestretch of three and was passively inflated to various predetermined states, and then actuated. The pole strains incurred during the inflation were as high as 25.6%, corresponding to slightly less than a hemispherical state. On actuation, the membrane would inflate further, causing a maximum additional strain of 9.5%. For the time-varying pressure experiments, the prestretched membrane was inflated and deflated mechanically while a constant voltage was applied. The membrane was cycled between various predetermined inflation states, the largest of which was nearly hemispherical, which with an applied constant voltage of 3 kV corresponded to a maximum polar strain of 28%. The results from these experiments reveal that the response of the membrane is a departure from the classical dynamic response of continuum membrane structures. The dynamic response of the membrane is that of a damped system with specific deformation shapes reminiscent of the classical membrane mode shapes but without same-phase oscillation, that is to say all parts of the system do not pass through the equilibrium configuration at the same time. Of particular interest is the ability to excite these deformations through a varying electrical load at constant mechanical pressure.

[1]  Danilo De Rossi,et al.  Dielectric elastomer cylindrical actuators: electromechanical modelling and experimental evaluation , 2004 .

[2]  N. C. Goulbourne,et al.  A Study on the Effect of Flexible Electrodes and Passive Layers on the Performance of Dielectric Elastomer Membranes , 2006 .

[3]  Erwan Verron,et al.  Dynamic inflation of non‐linear elastic and viscoelastic rubber‐like membranes , 2001 .

[4]  E. M. Lifshitz,et al.  Electrodynamics of continuous media , 1961 .

[5]  R. Pelrine,et al.  Electrostriction of polymer dielectrics with compliant electrodes as a means of actuation , 1998 .

[6]  Gabor Kovacs,et al.  Characterization of dielectric elastomer actuators based on a visco-hyperelastic film model , 2007 .

[7]  P. Frank Pai,et al.  Numerical and experimental dynamic characteristics of thin-film membranes , 2004 .

[8]  L. R. Schmidt,et al.  Biaxial stretching of heat-softened plastic sheets using an inflation technique☆ , 1975 .

[9]  Guggi Kofod,et al.  Dielectric elastomer actuators , 2001 .

[10]  J. Nemes,et al.  Membrane inflation of polymeric materials: Experiments and finite element simulations , 2001 .

[11]  R. Pelrine,et al.  Sound radiation properties of dielectric elastomer electroactive polymer loudspeakers , 2006, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[12]  Lochmatter Patrick,et al.  Characterization of dielectric elastomer actuators based on a hyperelastic film model , 2007 .

[13]  R. Toupin.  The Elastic Dielectric , 1956 .

[14]  Q. Pei,et al.  High-speed electrically actuated elastomers with strain greater than 100% , 2000, Science.

[15]  R. McMeeking,et al.  Electrostatic Forces and Stored Energy for Deformable Dielectric Materials , 2005 .

[16]  Eric Mockensturm,et al.  Electro-elastic modeling of a dielectric elastomer diaphragm for a prosthetic blood pump , 2004, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[17]  Hugh M. Herr,et al.  New horizons for orthotic and prosthetic technology: artificial muscle for ambulation , 2004, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[18]  J M Charrier,et al.  Free and constrained inflation of elastic membranes in relation to thermoforming — non-axisymmetric problems , 1989 .

[19]  Paulo B. Gonçalves,et al.  Dynamic non-linear behavior and stability of a ventricular assist device , 2003 .

[20]  Peter Sommer-Larsen,et al.  Response of dielectric elastomer actuators , 2001, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[21]  L. Hart-Smith,et al.  Large elastic deformations of thin rubber membranes , 1967 .

[22]  Nuri Akkas,et al.  On the dynamic snap-out instability of inflated non-linear spherical membranes , 1978 .

[23]  Jae Wook Jeon,et al.  Soft actuator for robotic applications based on dielectric elastomer: quasi-static analysis , 2002, Proceedings 2002 IEEE International Conference on Robotics and Automation (Cat. No.02CH37292).

[24]  D. D. Joye,et al.  A Bubble Inflation Technique for the Measurement of Viscoelastic Properties in Equal Biaxial Extensional Flow , 1972 .

[25]  D. A. Dunnett.  Classical Electrodynamics , 2020, Nature.

[26]  Ron Pelrine,et al.  Recent progress on electroelastomer artificial muscles and their application for biomimetic robots , 2004, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[27]  Z. Suo,et al.  A nonlinear field theory of deformable dielectrics , 2008 .

[28]  Yoseph Bar-Cohen,et al.  Electroactive Polymer (EAP) Actuators as Artificial Muscles: Reality, Potential, and Challenges, Second Edition , 2004 .

[29]  J. Maxwell.  A Treatise on Electricity and Magnetism , 1873, Nature.

[30]  T. Caughey,et al.  Classical Normal Modes in Damped Linear Dynamic Systems , 1960 .

[31]  Eric Mockensturm,et al.  Dynamic response of dielectric elastomers , 2006 .

[32]  Edoardo Mazza,et al.  Mechanical behavior of an acrylic elastomer used in dielectric elastomer actuators , 2007 .

[33]  Siegfried Bauer,et al.  Electromechanical characterization and measurement protocol for dielectric elastomer actuators , 2006, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[34]  R. Khayat,et al.  Dynamic inflation of hyperelastic spherical membranes , 1999 .

[35]  Alyson M. Tews,et al.  Pressure-volume characteristics of dielectric elastomer diaphragms , 2003, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[36]  Mary Frecker,et al.  A Nonlinear Model for Dielectric Elastomer Membranes , 2005 .