Magneto-mechanical properties of anisotropic magnetorheological elastomers with tilt angle of magnetic chain under compression mode

Characterization of mechanical properties of magnetorheological elastomers (MREs) is essential for the design of smart materials and devices with customized features and functionalities. While the properties of MREs under shear mode have been extensively researched, MREs with tilt angle under compression mode have been less exploited. In this study, a magneto-mechanical model of anisotropic MREs is established based on magnetic dipole theory and energy method considering the reconfiguration effect of compressive strain on the micro-structure of the magnetic chain. This leads to the provision of a dynamic magneto-mechanical model of the anisotropic MREs, incorporating the magneto-induced mechanical model, by using the robust fitting method. Experiments were conducted to assess the force-deflection (stress-strain) characteristics of MREs with tilt angle under compression mode, subject to the regulation of the tilt angle of magnetic chain, magnetic flux density, and mass fraction of magnetic particles. The magnetic-induced modulus, obtained from the theoretical model, is experimentally verified through magneto-mechanical testing, alongside an analysis on the dynamic mechanical properties under different dynamic strain amplitudes and frequencies. The mean square error (MSE) in terms of magneto-mechanical storage modulus in the robust fitting ranges from 2.73% to 10.86%. Experimental results also show that the range of magneto-induced stress (typically from 178 KPa to 74.6 KPa) decrease when the tilt angle of the magnetic chain increases (from 15 degrees to 25 degrees) corresponding to 60% mass fraction. The compression strain of the anisotropic MREs, affecting both the spacing of adjacent magnetic particles and the tilt angle of magnetic chain, causes significant changes in the magnetic-induced modulus. In addition, the hysteresis loops under different deformation (Mullins effect) show an increasing energy dissipation with decreasing tilt angle.