Characterization of hyperelastic materials for manufacturing soft bending actuators

Abstract

Unlike rigid link robots, the geometry and material properties of soft-bending actuators play an important role in preprogramming their bending behavior. The material properties of low-shore hardness silicones can be approximated through mathematical models of hyperelastic materials and can be determined experimentally using uniaxial and planer biaxial testings. This article investigates the bending behavior of soft actuators of similar geometry made of Elastosil M4601 and Smoothsil 950. Yeoh and NeoHookean mathematical models were selected to investigate the designed actuators in Abaqus simulation software. The effect of change in internal pneumatic pressures on the bending angles of actuators is investigated through simulations. Further, the bending behavior has also been investigated to verify the impact of strain-limiting layers. The results indicate that Elastosil M4601 is more sensitive to internal pressure and is suitable for low-pressure applications compared to Smoothsil 950. Comparisons between pneunets with and without strain layers indicate that there is a minimum or no effect of strain layer on the bending performance of the actuator with open wall configuration.