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Magnetorheological elastomers (MRE) are smart materials that have recently attracted considerable interest. The mechanical properties of MREs change significantly in the presence of a magnetic field. This study investigates the MRE properties and proposes a new model for designing systems using MRE. First, an MRE material fabrication process is introduced, and the dynamic properties of the MRE are investigated under different magnetic field strengths, frequencies, and amplitudes. The smooth Coulomb friction model is well known, representing the amplitude-dependent mechanical properties well. However, the model was inefficient when describing materials' properties at the low strain frequency (< 2 Hz). In this study, an improved Coulomb friction model has been developed to improve this problem by adding the strain velocity influence factor. Furthermore, the fractional viscous and variable stiffness models represent the material properties dependent on the frequency and magnetic field. Finally, a simple procedure, with easy computation, is proposed for determining the model parameters. The model results are compared with two classical models, the Coulomb model and the Bouc-Wen model. The developed model overcomes the disadvantages of the smooth Coulomb friction model when applied at low frequencies. Simulation and experimental results show that the proposed model achieves a deviation of just under 6 % in most cases, lower than when implementing the classical Coulomb friction (8 %) and hysteresis Bouc-wen models (7 %). The model also achieved similar accuracy when used for laminated MRE. [ABSTRACT FROM AUTHOR]

The magnetorheological elastomer (MRE) is an intelligent material whose mechanical properties can be rapidly adjusted under a magnetic flux density. This material's mechanical properties change due to the interaction between the iron particles inside the material. Understanding the influence of magnetic flux on iron particles in MRE materials is essential. Studies have proven that the distance and angle of inclination between iron particles significantly affect the magnetic flux density and the interaction force between the particles. Therefore, the distribution of iron particles substantially affects the material's properties. However, understanding magnetic flux through magnetic particles is necessary to improve the material's mechanical properties and to design magnetic field systems in systems using the materials. This study maps three problems affecting magnetic flux density to the properties of MRE. First, the mechanical characteristics of the MRE were presented in the frequency, amplitude, magnetic flux density, and magnetic flux inclination domains relative to the particle chain. Next, the influence of the magnetic flux on the particle chain was investigated based on the dipole interaction model and the magnetic force on iron particles. The finite element method also explored the magnetic flux distribution in the MRE material. Finally, the response of the single-degree-of-freedom damping system is tested experimentally. The results show that the influence of the magnetic flux on the iron particles in the MRE material is significant. The research results aim to improve the mechanical properties of MRE materials. [ABSTRACT FROM AUTHOR]

• A magnetic dipole model was proposed to simulate shear and hysteresis forces under different tilt angles. • The mechanical properties of the MREs are strongly dependent on the initial inclination of the particles. • The magneto-induced stiffness reached a higher value with tilt angles 0° and 25°. • The magnetically induced hysteresis behavior of the MRE materials is strongly dependent on the tilt angle of the particles. • The system achieved high efficiency when the tilt angle between magnetic field direction and particle chain was from 0° to 25°. Magnetorheological elastomers (MRE) are smart materials whose mechanical properties can be tuned using an applied magnetic field. Many studies have shown that MRE properties are influenced by particle size, particle volume fraction, and matrix material type. The particle-magnetic dipole theory has demonstrated that the angle of the particle chains significantly affects the properties. This study investigated the effects of the alignment angle of the particle chains on the properties of MREs. The inclination angle is a parameter associated with the external magnetic flux density. MRE samples fabricated under a magnetic field with different tilt angles were prepared for the shear tests. The primary properties of MRE, such as viscoelasticity, magnetic-induced properties, and hysteresis, were comprehensively investigated in the samples. The equivalent stiffness and loss of energy changed significantly in the tilted angle domain. The force–displacement loops also showed a clear difference among the samples when the experiments were performed at the same amplitude, frequency, and magnetic flux density. The experimental results show that the magnetic and hysteretic properties strongly depend on the initial tilt angle of the chain. [ABSTRACT FROM AUTHOR]