Isotropic magnetorheological elastomers (MREs) with hybrid-size particles are proposed to tailor the zero-field elastic modulus and the relative magnetorheological rate. The hyperelastic magneto-mechanical property of MREs with hybrid-size CIPs (carbonyl iron particles) was experimentally investigated under large strain, which showed differential hyperelastic mechanical behavior with different hybrid-size ratios. Quasi-static magneto-mechanical compression tests corresponding to MREs with different hybrid size ratios and mass fractions were performed to analyze the effects of hybrid size ratio, magnetic flux density, and CIP mass fraction on the magneto-mechanical properties. An extended Knowles magneto-mechanical hyperelastic model based on magnetic energy, coupling the magnetic interaction, is proposed to predict the influence of mass fraction, hybrid size ratio, and magnetic flux density on the magneto-mechanical properties of isotropic MRE. Comparing the experimental and predicted results, the proposed model can accurately evaluate the quasi-static compressive magneto-mechanical properties, which show that the predicted mean square deviations of the magneto-mechanical constitutive curves for different mass fractions are all in the range of 0.9-1. The results demonstrate that the proposed hyperelastic magneto-mechanical model, evaluating the magneto-mechanical properties of isotropic MREs with hybrid-size CIPs, has a significant stress-strain relationship. The proposed model is important for the characterization of magneto-mechanical properties of MRE-based smart devices.
Keywords: extended Knowles model; hybrid size; hyperelastic property; isotropic MRE; magneto–mechanical compression.