Effects of applied strain, magnetic field, and temperature on the compressive stress relaxation behavior of magneto-sensitive elastomers

The paper investigates the short- and long-term compressive stress relaxation behavior of isotropic and anisotropic magneto-sensitive elastomers (MSEs) prepared by incorporating carbonyl iron microparticles into a silicone rubber. The effects of applied compressive strain, magnetic field, and temperature on the short-term stress relaxation behavior of the isotropic and anisotropic MSEs were determined up to 1200 s. The stress relaxation behavior of the MSEs considerably depended on the applied compressive strain, magnetic field, and temperature. The stress of the MSEs increased with increasing compressive strain and magnetic-field intensity, but decreased with increasing temperature. The isotropic MSE exhibited approximately linear elastic behavior, while the anisotropic MSE revealed nonlinear elastic characteristics. The compressive stress and the relaxation modulus of the anisotropic MSE are considerably higher than those of the isotropic MSE. The compressive stress relaxation behavior of the isotropic and anisotropic MSEs was simulated using a fractional derivative viscoelastic Kelvin–Voigt model. The model parameters were identified by fitting the relaxation modulus to the short-term measured data of the MSEs. The compressive stress estimated from the studied model with fitted parameters was in excellent agreement with the measured data of the MSEs at different compressive strains, magnetic fields, and temperatures. The model was then used to estimate the long-term stress relaxation of the MSEs. An excellent agreement between long-term predicted results and experimental data of the MSEs has been reached when fitting the model to the medium-term experimental data.