Date of Award
Master of Science
Ashraf F. Bastawrows
Electroactive polymers have been studied for artificial muscle applications in last decades. One of the EAP materials, 3M VHB acrylic tapes, have shown been outstanding electro-mechanical coupling performance. The scope of this study is to understand the electro-mechanical properties of VHB acrylic material. In addition, the research explores new practical designs of soft actuators. The basic designs employ directional planar stiffeners that act as geometric constraints. The utilization of these stiffeners provides the ability to tailor the planar deformation into many three dimensional deformed shapes.
In the first part of this work, the material nonlinear mechanical response is characterized using a pre-stretched planar configuration with different bi-axial stretch ratios. Also, unequal bi-axial stretch ratios were also investigated. During the course of deformation, high resolution images of the deformed state were in situ captured. The images were analyzed by digital image correlation technique to evaluate the in-plane finite strain components. The measurements are used to calibrate a Neo-Hookean based material model that couples the applied electrical field to the actuator mechanical deformation. The material model is built into a user-material subroutine with the ABAQUS commercial finite element package. The numerical model is used to optimize different geometrical feature, electrode layup and stacking sequence for the actuator in order to attain a prescribed deformation pattern. The developed framework will aid in designing and optimizing the EAPs actuator configurations for general 3D prescribed deformation configuration.
In the second part of our work, we presented a new actuator design featuring a freestanding configuration without the constraints of pre-stretch. By using different configuration of stiffener reinforcement, the proposed design presented various complex three dimensional motions. A simple one-dimensional planar stiffener is utilized to measure the resulting curvature of the deformed configuration under different level of applied voltage. The Timoshenko-bimaterial laminate solution is employed to assess the electrical to mechanical conversion efficiency. The developed framework will address more complex 3-D deformation. The whole work is a first step towards the development of soft actuators for artificial muscle applications.
Lai, William, "Characteristics of dielectric elastomers and fabrication of dielectric elastomer actuators for artificial muscle applications" (2011). Graduate Theses and Dissertations. 12183.