Development and finite element analysis of a magnetorheological elastomer for stiffness variation in a soft manipulator

Abstract

Rigid robots and their inadequate adaptation to challenging environmental conditions requires new intelligent systems. This demand has empowered the evolution of soft robots, that have high dexterity, deformability, and compliance. One crucial requirement for soft robots is the variable stiffness as this provides the potential for tuning the forces exchanged with the environment. Adaptation of smart materials, which can undergo stiffness variations because of the applied physical stimuli, is one of the proposed methods in the literature. Magnetorheological elastomers (MREs) are a type of smart material whose rheological behavior can be changed as a result of the applied magnetic field. MREs generally consist of natural or synthetic rubber perfused with micron sized ferromagnetic particles. In this thesis, an isotropic MRE has been developed to provide stiffness variation for a soft manipulator, which is the STIFF-FLOP. A stand-alone MRE module for stiffness variation has been developed, and tested, an intended application of this MRE module to the STIFF-FLOP soft manipulator is proposed. To capture MRE’s material behavior adequately, an analytical method currently used in literature has been advanced by further development. The proposed model has then been implemented in a finite element analysis (FEA) software. This FEA model was compared with the existing method, and experimentally validated. Once the developed FEA was validated, it was used to analyze the stiffness change that might occur due to a possible implementation of the MRE module in the STIFF-FLOP. Results indicate that the proposed FEA is capable of capturing the material behavior of the developed MREs. Results also show that the intended application might benefit from MREs by obtaining highly changing stiffness values.