Simon Fraser University

The behavior of a Spherical Electroactive Polymer Actuator

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Researchers in the MENRVA group in the Department of Applied Science/ Engineering at Simon Fraser University are using MSC Marc to investigate the sandwich type compression of a Spherical Electroactive Polymer Actuator (SEAPA) as preliminary investigations into spherical actuator utilities. The hope of this research is to apply knowledge of the system to spherical planetary exploration devices where regular compressions and frictions can occur.

The SEAPA comprises of a thin spherical shell comprised of an incompressible material that can be actuated to expand the shell in the thickness direction. The shell is sealed to form a cavity with a constant gas mass. Stiff plates are then used to compress the sphere in sandwich type compression to produce a force measurable on the plates. Due to the constant gas mass inside the SEAPA, when the shell is actuated the total volume of the sphere is increased and the pressure applied by the gas inside is then subsequently decreased causing a decrease in the force applied to the plate.

The current research is focused on the verification of the experimental measurements already conducted and optimizing the designed for different loading considerations. The inflation of the sphere, shown in Figure 1, is essential to understanding the non-linear behavior on the spherical geometry.

The FE Modeling has been completed with MSC Marc. Herman elements, intended for incompressible materials were used to model the rubber. The built in cavity formation tool and contact mechanics were also vital solving our problem. Changing frictions between the plate and SEAPA allow us to examine potential interactions for the spherical rovers. The compression of the sphere is shown in Figure 2. Working with Marc and Mentat has enables us to model the SEAPA and modify the design parameters which are too costly to verify experimentally.