Effect of intensity of orientational magnetic field on steady shear behavior of magnetorheological elastomers

As filled elastomers, magnetorheological elastomers (MREs) undergo changes in their shape and physical and mechanical properties in response to an external magnetic field. To investigate how applying an orientational magnetic field during fabrication influences the magnetomechanical properties of MREs, several types of samples with different matrix properties were prepared and examined in lap shear tests under a magnetic field. The results show that with increasing orientational magnetic field and silicone-oil content, (i) the chain arrangement of the magneto-sensitive particles in the matrix becomes more obvious and (ii) the magneto-induced shear modulus and the magnetorheological effect of the prepared materials increase. To elucidate qualitatively the magneto-induced performance of MREs cured in different external magnetic fields, a microphysical model is proposed based on an exponential distribution of the angle between the magnetic-field direction and the chains formed by the magnetic particles, thereby to reduce the error due to the assumption of a uniform distribution. The present results provide a theoretical basis for designing and preparing magneto-sensitive smart materials.