In this research work, two different compositions of MR fluid samples with 24 and 30 percentage (%) volume fraction of carbonyl iron (CI) particles are prepared. Prepared MR fluid (MRF) samples contain carbonyl iron particles as a dispersive medium, silicone oil as a carrier fluid, and white lithium grease as an anti-settling agent. Influence of oscillating driving frequency, strain amplitude, magnetic field, and the percentage of CI particle on the rheological properties of the MR fluid samples are presented. Storage modulus and loss factor equations are estimated from the rheometry results using a linear regression method. The properties of MR fluid samples are taken to design and model the sandwich beams using ANSYS ACP software, where carbon epoxy composite material is used as the face layer and MR fluid as the core material. Modal, harmonic, and transient analysis studies have been conducted on all the modelled sandwich beams. Influence of MR fluid core material thickness, face layer thickness, CI particle volume percentage in the prepared MR fluid sample, and magnetic field on the vibrational response of the sandwich beams have been presented. Carbon-epoxy composites with an in-house made MRF sandwich beam has shown some significant results in the vibrational response.

One of the common ways to reduce vibration in the structures is to add a thin viscoelastic material layer to the structure. By appropriate use of viscoelastic materials one may increase modal loss factor of the structure and reduce unfavorable structural vibration which is a main cause of fatigue and failure in the structures. In this paper, low velocity impact response of sandwich plate with Magnetorheological fluid core is investigated. Hamilton principal is used to obtain the governing equation of motion for sandwich plate. Free vibration problem of the sandwich plate is solved using the Navier solution method.Classical lamination theory is used to analyze the mechanical behavior of the composite laminate in the facesheet. Only shear strain energy of the core is considered and viscoelastic behavior of the MR material was described by complex shear modulus approach as a function of magnetic field intensity.Furthermore, analytical solution for impact force is obtained by a two degree of freedom spring mass model. For three different stacking sequence of face layers, contact for history and variation of maximum impact force and its corresponding time by magnetic field intensity is investigated. The results show considerable effect of variation in magnetic field intensity on maximum impact force and its corresponding time.

In this paper, the analysis of nonlinear free vibrations of beams made of functionally graded materials with Magnetorheological fluid as core is investigated. It is assumed that the beam is made of three layers including constraining layer, Magnetorheological fluid and base layer and is located on Simply-Simply, Clamped-Simply and Clamped–, Clamped supports. The governing equations of the beam are derived using the Hamilton’, s principle. To obtain the vibrational frequencies, the theory of Timoshenko beam is used by the Generalized Differential Quadrature method. The effects of magnetic field intensity, power law exponents, core thickness and constraining layer thickness and the length of the beam on natural frequency and modal loss factor related to different frequencies modes for the three boundary conditions have been investigated. The results show the effects of physical and geometrical parameters regarding the natural frequency and modal loss factor of the sandwich beam with different modes. Also, the frequency and loss factor values obtained from Generalized Differential Quadrature method are very close to the results obtained by the Finite Element method. This shows the accuracy and precision of this method.

In this paper, the free vibrations of a three-layer sandwich plate with magneto-rheological fluid (MR) core as a smart structure using Trigonometric Shear Deformation Theory (TSDPT) are investigated. The equations of motion are obtained using the Hamilton principle and solved using the Galerkin residual weight method. The complex shear modulus of the MR material in the pre-yield region was described by complex modulus approach as a function of magnetic field intensity. Primary attention is focused on the effects of magnetic field magnitude, geometric aspect ratio, and MR core layer thickness on the dynamic characteristics of the sandwich plate. When an electric field is applied, the damping of the system is more effective. After validation of the present study with the available results in the literature, the effects of the natural frequencies and loss factors on the dynamic behavior of the sandwich plate are examined and discussed. The results show that increasing the intensity of the magnetic field increases the frequency and depreciation coefficient of each mode. Furthermore, increasing the thickness of the fluid has a direct effect on increasing the depreciation coefficient and decreasing the frequency. With the increasing use of smart structures, it is hoped that the findings of this study will make engineering applications more effective.

The novel controllable behaviour of Magnetorheological (MR) fluid is the backbone of Magnetorheological fluid-based finishing processes. MR fluid-based finishing processes facilitate better control over finishing forces as the stiffness of MR finishing fluid used in these processes can be controlled in accordance with the applied magnetic field and MR finishing fluid composition. Therefore, a detailed experimental investigation was carried out to find the effect of MR finishing fluid constituents on its yield stress through the Taguchi Design of Experiments. Rheological data obtained from a magneto-rheometer (MCR-102) was characterised by using Bingham plastic, Herschel– Bulkley and Casson’ s fluid constitutive modelling. The coefficient of regression (R2) values of Herschel– Bulkley model were found to be best suited for all compositions of MR finishing fluid. Analysis of variance (ANOVA) has been used to find the contribution of selected parameters for improving the response characteristics. The optimized fluid has been then used for the finishing of biocompatible stainless steel AISI 316L, and the finishing results show that the average surface roughness value decreases down to 58 nm.

Magnetorheological fluids contain suspended magnetic particles that arrange in chains in the presence of a magnetic field, causing the conversion of the fluid from a liquid state to a quasi-solid state. These fluids can be used in valves as a tool for pressure drop and flow interruption. This research aims to investigate the feasibility of using the Magnetorheological fluid (MRF) in industrial valves. The rheological properties of the MRF sample were measured with the MCR300 rheometer in the presence of a magnetic field. In this connection, the Bingham plastic continuous model was used to predict the fluid behavior, and the model coefficients were obtained using MATLAB software. Then, the model coefficients were used to simulate the behavior of the Magnetorheological fluid in the presence of the magnetic field in the valve. The geometry and dimensions of the valve were designed according to the dimensions of industrial samples. Then the CFD simulation with Fluent software was done by using the Bingham model and fluid characteristics obtained from experimental results. The results showed that the pressure increased by increasing the magnetic field at the center of the sleeve. The magnetic field of up to 0. 5 Tesla, increases pressure and decreases amplitude. Therefore, as the magnetic field increased, the amplitude of the maximum pressure on the sleeve was significantly reduced.

Magnetorheological (MR) materials indicate variations in their rheological properties when subjected to different magnetic fields. This study presents vibration analysis of laminated composite plates using MR fluid lumps. A structural dynamic modeling approach is presented to investigate the vibration characteristics of MR adaptive structures for different magnetic fields. The effects of laminate configurations and locations of MR fluid lamps on the controlled response are investigated. Vibration responses of the laminated plate have been simulated to demonstrate the accuracy and efficiency of the present approach. The results of this work may improve the dynamic performance of composite structures which are subjected to undesirable vibration during operation such as helicopters blades.

Magnetorheological (MR) fluid finishing process is an application of MR technology in which controllability of the MR fluid is used advantageously to finish the workpiece surface. MR finishing fluid changes its stiffness in accordance with the applied magnetic field and hence it behaves like a flexible finishing tool. A relative motion between this tool and workpiece removes the material from the machining surface. The quality of the final finished surface depends on the constituents of the finishing fluid and the applied magnetic field strength as these parameters affect the rheological properties of the fluid. A study on the rheological properties of the fluid at high shear rates is carried out through Taguchi Design of Experiments to characterize its flow behaviour to be used in continuous flow finishing process. Constitutive modeling of the fluid sample is done using Bingham Plastic, Casson fluid and Herschel Bulkley fluid models to characterize their rheological behavior. The Hershel– Bulkley model is found to be the best suited model for the finishing fluid. Analysis of Variance has revealed that volume percentage of iron particles is the most significant parameter with a contribution of 91. 68% on the yield stress and viscosity on the finishing fluid. The highest yield stress of the fluid is observed between magnetic flux density ranges from 0. 3 to 0. 5 Tesla. An optimised combination is then synthesized to confirm the theoretical results. The effect of temperature is also studied on the optimised fluid which has shown that temperature shares an inverse relation with the yield stress of the finishing fluid.

Sedimentations and hard cakes formation of magnetic particles restrict Magnetorheological fluid response to magnetic field and can cause the MR fluid containing device to collapse. Therefore, researches on MR fluids sedimentation reduction procedures and its effective factors are of considerable interest to improve Magnetorheological applications. In this study, the effects of some parameters on typical MRF stability were investigated. For this purpose, at first, MRF samples were constructed and the effects of various factors including carrier fluid type, particles concentrations and MRF mixing methods on its stability were investigated and the importance of each factor was determined by Taguchi algorithm and the stable MRF sample for application of Magnetorheological dampers was chosen. Next, by investigating the most stable MRF sample, based on the combination of stability and off-state viscosity factors, the relation for yield stress in various magnetic fields was presented. This relation was derived based on fitting the Herschel- Bulkley model with experimental data in conjunction with the existing relations of yield stress. As the results show, after 168 hours, sedimentation for the most stable sample is 7%. This sample consists of silicon oil and 70%wt iron powder which was prepared with mechanical stirrer. Adding 3%wt stearic acid to carrier fluid for increasing the stability results in increasing the viscosity of carrier fluid up to 39 times. In spite of this, an acceptable MR effect is presented so that, in magnetic field of 146 kA/m the sample yield stress is 15KPa.