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In this paper a new model is developed to describe the response of Magneto-rheological fluids (MRF) in transient state. The models which are developed so far, cover the steady-state flow, or address the transient state, with step-wise input electrical current and constant shear rate. In this paper, a new model for transient state of MRF is developed in which the input electrical current is an exponential function in different values of shear rate. Due to the magnetic inertia caused by the inductance of the coil, the real magnetic flux density could not be step-wise. Hence, compare with the other models, this model is in well agreement with reality. To verify the presented model and study the fluid properties as input parameters, an experimental coupling is designed and fabricated. The coupling applies magnetic field perpendicular to shear direction, and measures the shear stress as a function of time. The results of the proposed model show acceptable agreement with experimental observations. According to experimental and theoretical results, the presented model is applied to a controllable torque coupling and acceptable results were obtained.

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In this article, the physical and Geometrical effective parameters on free vibration and Force impact a three-layer sandwich plate in the middle layer with magneto rheological (core) Under cross-shot with low speed is investigated. The first natural frequency and loss factor of comparable modal for the first four vibrative modes for Core thickness, magnetic fields and different sheet’s geometrical parameters, is founded. The MR material shows variations in the rheological properties when subjected to varying magnetic fields. These materials with fast response time (in milliseconds) Through a detailed with variation in Magnetic field can be controlled. The governing equations of motion were obtained using Hamilton̕s principle. The results were obtained by the systematic analytical solution. Using the two degrees of freedom mass-spring model, the contact force function can be obtained analytically. The obtained natural frequency from eigen value problem, was used for calculating of equivalent mass of the plate in spring mass model. The results show that with systematic variation of magnetic field and with increasing the ratio of core thickness to the layer thickness and also with increasing the ratio of length to the whole of sheet thickness, we can in order, the stiffness, structural loss factor coefficient and maximum contact force can be changed and controlled.