Mechanical responses of Ecoflex silicone rubber: Compressible and incompressible behaviors

Silicon rubbers are widely used in a variety of products ranging from cooking utensils and electronics to medical devices and implants. Recently, they have sparked an interest among soft robotics researchers as they can be easily formed into various shapes and actuated in a relatively fast and easy way. In this article, we examine the nonlinear elastic response of a silicon rubber, Ecoflex, under both compressible and incompressible constraints. An experimental test on a uniaxial tension indicates a slight compressibility, and the compressibility increases with stretching. Five different constitutive material models are considered to describe the nonlinear elastic responses of Ecoflex under both compressible and incompressible conditions. In addition, finite element (FE) analysis is presented to analyze multiaxial response of structures or devices made of Ecoflex under complex boundary conditions. This study highlights the variations in the multiaxial response of structures at large deformations from different constitutive models under different compressible and incompressible constraints. For a high precision control in soft robotics applications, there is a need to understand the multiaxial response of silicon rubbers, especially under large deformations. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47025.