Study on the stiffness and damping properties of magnetorheological elastomers subjected to biaxial loads and a magnetic field

This study explores the variation in stiffness and damping properties of magnetorheological elastomers (MREs) specimens made with two concentrations of carbonyl iron particles aligned at 45° and 90° concerning the horizontal axis of an electromagnetic quadrupole installed in a biaxial testing device that generates a homogeneous magnetic field at the center of the specimen. To investigate how the specimen strain changes with the magnetic field, the specimen's biaxial deformation behavior was analyzed using the digital image correlation (DIC) technique when a magnetic field is applied through an electromagnetic quadrupole capable of adjusting the orientation and intensity of the incident magnetic field. We discovered that micro-particle alignment in the elastomer matrix, its fractal structure, and the magnetic field modify stiffness and damping properties since the magnetic field restricts the polymer chains' reptation zone, thereby stiffening the polymer matrix and influencing its energy dissipation capacity. Furthermore, we proposed a constitutive material model to predict stress-softening and residual strains when the MRE samples are under biaxial loading-unloading cycles and magnetic field intensity with theoretical predictions that follow experimental data well. Our findings elucidate how the alignment of carbonyl iron particles and the magnetic field influence MRE behavior, enabling adaptive tuning of the material stiffness and damping properties. • This article elucidates how magnetorheological elastomers respond to biaxial stress when subjected to magnetic fields. • The fractal iron microparticle arrangement added in the elastomer matrix influences the composite material's properties. • Digital Image Correlation (DIC) measures biaxial strains in real time, elucidating the MRE's deformation mechanism. • The relative angle of the aligned magnetic particles and the applied magnetic field affect the physical properties of MREs. • Magnetic fields increase the MREs' properties, enhancing their applicability for adaptive and energy-dissipative systems.