The present multidisciplinary study focuses on providing a model for Magnetorheological dampers. First, it presented a brief look at the existing models of such dampers, and then to achieve an invertible, efficient, and at the same time simple model, the Kwok model has been selected and has changed appropriately. A new identification algorithm based on meta-heuristic methods has been proposed to identify the model, which has used periodic excitation. This algorithm has high detection capability with the minimum necessary tests. To evaluate the proposed model and identification method, a large-scale Magnetorheological damper, which is placed as a black box model in the benchmark baseisolated building introduced by the US Structural Control Committee, has been used as a virtual laboratory. The whole process has been investigated in the Simulink environment of MATLAB. The performance of the proposed model was compared with the original one under seven near-fault earthquakes. The results show that the modified Kwok model is more accurate than the original one. It can predict force-displacement and force-velocity behaviors correctly. Also, since the proposed model is invertible, it is easily applicable in practical issues of structural control. It provides the possibility of managing control devices, so is superior to the Kwok model.

In this paper, semi-active response control of tall buildings equipped with Magnetorheological dampers is studied. Clipped-optimal control algorithm based on linear quadratic regulator (LQR) is employed for semi-active controller design. Bouc-Wen phenomenological model is utilized to investigate the nonlinear behavior of the MR dampers. The performance of the resulting control system is compared to the uncontrolled structure for a benchmark building through simulation, and the efficiency of using MR dampers is evaluated.

TitleA review of the performance parameters of Magnetorheological vibration dampers.Abstract The development of Magnetorheological vibration dampers with the aim of preventing the adverse effects of vibrations has attracted the attention of researchers and industrialists in recent years. From the point of view of physical structure, these dampers are usually divided into three categories: single pipe, double pipe and bilateral, which are used in different shear, pressure, flow and combined modes. Magnetorheological fluids are among smart magnetic materials that exhibit different rheological properties when exposed to a magnetic field compared to the state without the application of a magnetic field, and with the increase in coercivity, the applied magnetic field and the amount of force required to cause deformation in the fluid increases. Magnetorheological vibration dampers are used to reduce vibrations transmitted to car seats, smart brakes in knee prostheses, dampers used in bridges, construction industry and military industries.

Magneto rheological (MR) dampers have the advantage of being tuned by low voltages. This has attracted many researchers to develop semi-active control of structures in theory and practice. Most of the control strategies first obtain the desired forces of dampers without taking their dynamics into consideration and then determine the input voltages according to those forces. As a result, these strategies may face situations where the desired forces cannot be produced by the dampers. In this article, by integrating the equations of the dynamics of MR dampers and the structural motion, and solving them in one set, a more concise semi-active optimal control strategy is presented, so as to bypass the aforementioned drawback. Next, a strong database that can be utilized to form a controller for more realistic implementations is produced. As an illustrative example, the optimal voltages of the dampers of a six-storey shear building are obtained under the scaled El-Centro earthquake and used to train a set of integrated analysis-adaptive neuro-fuzzy inference systems (ANFISs) as a controller. Results show that the overall performance of the proposed strategy is higher than most of the other conventional methods.

Fuzzy control has recently been proposed to control the properties of Magnetorheological (MR) dampers and therefore reduce vibrations of civil structures subjected to earthquake loads. These controllers have the advantage of not depending on system model, of being simple, and intrinsically robust. Their tuning, however, has shown to be a difficult task. This paper proposes a gain-scheduled fuzzy controller to regulate the damping properties of MR dampers and reduce structural responses of single degree-of-freedom seismically excited structures. Robustness of the algorithm to changes in seismic motions and structural characteristics were assessed by subjecting two different one-story buildings, one rigid and one flexible, to a wide range of earthquake records. Results show that the algorithm proposed effectively reduced responses of both structures to all twenty-four earthquake motions considered. In addition, results were compared to those of a fuzzy controller with constant scaling factors and to those of two passive systems: "passive on" and "passive off", where the current to the MR damper was set at maximum allowable value, and zero, respectively.

This study investigates the efficacy of optimal semi-active dampers for achieving the best results in seismic response mitigation of adjacent buildings connected to each other by Magnetorheological (MR) dampers under earthquakes. One of the challenges in the application of this study is to develop an effective optimal control strategy that can fully utilize the capabilities of the MR dampers. Hence, a SIMULINK block in MATLAB program was developed to compute the desired control forces at each floor level and to the obtain number of dampers. Linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG) controllers are used for obtaining the desired control forces, while the desired voltage is calculated based on clipped voltage law (CVL). The control objective is to minimize both the maximum displacement and acceleration responses of the structure. As a result, MR dampers can provide significant displacement response control that is possible with less voltage for the shorter building.

In this study, the effect of using passive optimized tuned mass dampers and semi-active Magnetorheological dampers separately and simultaneously in controlling the seismic vibrations of a steel structure has been evaluated, considering nonlinear behavior of the structure. The OpenSees software is used to model the steel structure and tuned mass damper, and MATLAB software is used to model the effect of the Magnetorheological damper. In the MATLAB software, the appropriate control voltage for the Magnetorheological damper is determined by implementing fuzzy logic with decisions based on velocity and displacement. The TCP/IP network is used as a communication bridge to connect the two softwares. Incremental dynamic analyses were performed using 7 earthquakes. Based on the results, the fuzzy logic algorithm has resulted in a better adaptation of the combined system of mass and Magnetorheological dampers with the behavior of the structure. In fact, the combined control system, in addition to reducing the maximum response of the structure under the main pulse of the earthquake, has a great ability to reduce the response of the structure under the effect of weaker pulses. The combined mass and Magnetorheological dampers control system has improved the maximum roof displacement of the structure by 23 percent compared to the passive control system with the tuned mass damper. The result for the maximum base shear of the structure is 27.9. The percentage of improvement in the dispersion values of the roof displacement and base shear in the aforementioned systems is 22.1 and 25.9, respectively.

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.

The present study focusses on the damping force control of shear mode Magnetorheological (MR) damper for seismic mitigations. Therefore, the semi-active MR damper which can control the vibration is analyzed both experimentally and numerically. Carbonyl iron is used as the magnetic particle and Castrol Magnetec oil as carrier fluid throughout the study. MR damper is designed and fabricated, and its damping force was evaluated experimentally at 2. 5 A-10 V. Shear mode MR Damper is tested in universal testing machine using time history loading. The model was numerically analyzed using Newmark’ s method for nonlinear system in MATLAB to control the three storey model building frame taken from the literature. The result indicates that 49. 42% reduction in displacement at the second storey and 48. 14% in the third storey, respectively. Maximum reduction was observed when damper was kept in the ground floor. The maximum force observed for the MR Damper is 0. 777 kN.