The magneto-mechanical coupling of multiphase magnetorheological elastomers

Magnetorheological elastomers (MREs) are soft magnetic composites that achieve tunable changes in stiffness and damping in the presence of a magnetic field. Rigid particle composite (RC) MREs have been studied for decades for their potential applications to automotive dampers and robotic systems. Recently, magnetic fluid composite (FC) MREs have been developed which utilize magnetic fluids as inclusions to elastomers. An investigation into how inclusion phase affects magneto-mechanical performance may greatly improve MRE design capabilities. Here we experimentally evaluate the impact of solid and liquid magnetic inclusions on MRE properties, construct a simple model that captures the performance of diverse MRE material architectures, and demonstrate the use of the model to create material design maps relating the material structure, zero-field properties, and applied field to the elastic modulus and specific loss. The magneto-mechanical response is evaluated for three material architectures: RC, FC, and hybrid composite MREs that use solid particles, magnetic fluids, and a combination of the two as inclusions respectively. The model is developed through magnetic and mechanical energy principles, which suggests that the phase of the magnetic inclusions impacts the change in energy density during deformation. We show that the magneto-mechanical coupling factor is dependent on the zero-field properties of the composites, which allows for the development of material design maps to inform the fabrication of MREs based on desired properties.