Large-scale Magnetorheological Damper Research Articles

PERFORMANCE EVALUATION OF A SMALL-SCALE MAGNETORHEOLOGICAL DAMPER FOR CIVIL ENGINEERING APPLICATIONS

Magnetorheological dampers (MRDs) are devices that adjust their damping properties in response to an external magnetic field. Large-scale MRDs have been successfully used as vibration control devices in structures. This study focuses on modelling and optimizing an MRD using COMSOL Multiphysics. Various parameters, such as coil turns and current, are optimized to achieve the maximum flux value in the MRD. The simulation yielded a maximum magnetic flux of 0,44 T with 500 coil turns. Based on the optimized MRD parameters, a numerical equation is then used to calculate the total damping force. The maximum numerical and experimental damping forces corresponding to a 2,0 A current were 989,39 and 1004,63 N, respectively. The numerical damping force is then compared to the experimental results to validate the accuracy of the model. The MRD is integrated into a scaled-down reinforced concrete frame and subjected to a cyclic loading test for performance evaluation. The results show that the MR dampers improve the performance of the frame structure, increasing its load-carrying capacity and energy dissipation by 19,45 % and 20,43 %, respectively. The findings of the study provide valuable insights into the behaviour of MRDs and their optimization using numerical simulations, as well as highlight the importance of experimental validation for accurate prediction of the performance of MRDs in practical civil engineering applications.

Experimental research on the seismic properties of shear wall reinforced with high‐strength bars and magnetorheological dampers

Magnetorheological (MR) damper was a kind of smart instrument, and it was very suitable for the semi-active control. In this research, a large-scale MR damper working in the shear mode of the MR fluid was developed to enhance the mechanical properties of the shear wall. The influence of MR damper on the mechanical properties of the shear walls, such as stiffness, strength, ductility, and the energy dissipation capacity, had been researched. Firstly, both the model of MR damper and shear wall were established to optimize the properties of the MR damper and shear wall. Then, three different concrete shear walls were fabricated, which were reinforced by carbon fiber-reinforced polymer (CFRP) bars (W-1), CFRP bars and MR dampers (W-2), and steel strands and MR dampers (W-3), respectively. The mechanical properties of the specimens were experimentally researched and analyzed. The experimental results showed that the ductility, the ability to bear external loads, stiffness, and energy dissipation capacity of the shear walls could be enhanced by the MR damper simultaneously. Compared with W-1, the ductility, the ability to bear external loads, ultimate deformation, and energy-dissipation capacity of W-2 increased by 4.1%, 26.8%, 83.9%, and 35.8%, respectively. The residual deformation of the three shear walls was almost the same. The results indicated that the MR damper could enhance the mechanical properties of the shear walls and had no influence on the self-centering capacity of the shear walls at the same time.

An asymmetric-friction based model for magnetorheological dampers

The modeling of magnetorheological dampers combines the use of the laws of physics along with a phenomenological description. The phenomenological models that are used to describe these devices present a symmetric hysteresis loop. However, the experimental hysteresis loops of MR dampers are not symmetric. To take into account this asymmetry, we propose a modification of the viscous + Dahl model, use the modified model to describe a large-scale magnetorheological damper, and validate the modified model against experimental data.

Large-Scale Real-Time Hybrid Simulation for Evaluation of Advanced Damping System Performance

AbstractAs magnetorheological (MR) control devices increase in scale for use in real-world civil engineering applications, sophisticated modeling and control techniques may be needed to exploit their unique characteristics. Here, a control algorithm that utilizes overdriving and backdriving current control to increase the efficacy of the control device is experimentally verified and evaluated at large scale. Real-time hybrid simulation (RTHS) is conducted to perform the verification experiments using the nees@Lehigh facility. The physical substructure of the RTHS is a 10-m tall planar steel frame equipped with a large-scale MR damper. Through RTHS, the test configuration is used to represent two code-compliant structures, and is evaluated under seismic excitation. The results from numerical simulation and RTHS are compared to verify the RTHS methodology. The global responses of the full system are used to assess the performance of each control algorithm. In each case, the reduction in peak and root mean s...

Robustness studies of sensor faults and noises for semi-active control strategies using large-scale magnetorheological dampers

This paper presents comparative studies for various sensor faults and noise effects on the performance of several recently proposed semi-active control algorithms for the control of large-scale magnetorheological dampers. Sensor faults or noises due to various environmental factors and long-term deteriorations may cause degradations in the performance of the control system. In this paper, the authors have carried out an in-depth literature review of the sensor fault or malfunction and noise problems, diagnostic methods and compensation approaches applicable to semi-active control algorithms. For three recently developed semi-active controllers, namely clipped optimal control, decentralized output feedback polynomial control and Lyapunov controller, an extensive study has been carried out on the robustness of these controllers during sensor faults and noise effects. Based on this research, a new real-time qualitative model-based sensor fault detection and diagnosis (RMSFDD) method has been proposed. This novel RMSFDD method shows a good performance during diverse sensor fault types in semi-active control with a real-time application without any training and heavy computational cost.

Direct performance-based design with 200 kN MR dampers using multi-objective cost effective optimization for steel MRFs

Direct performance-based design methodology that incorporates traditional performance-based design and semi-active smart damping devices (i.e., magnetorheological (MR) damper) has been investigated through the application of multi-objective optimization. This design method achieves multiple objectives in which cost and efficiency are simultaneously optimized to achieve multiple performance levels subjected to multiple hazard levels. For numerical study, large-scale 200kN MR dampers have been installed in a 9-story moment-resisting frame building to carry out multi-objective optimization using genetic algorithm. Minimum interstory drift during through nonlinear time history analysis and minimum number of MR dampers installed are considered as performance-based design objectives. Several MR damper location layouts have been obtained through the optimization. Nonlinear time history analyses have been carried out to evaluate performance of each MR damper device layout.

Over-driven control for large-scale MR dampers

As semi-active electro-mechanical control devices increase in scale for use in real-world civil engineering applications, their dynamics become increasingly complicated. Control designs that are able to take these characteristics into account will be more effective in achieving good performance. Large-scale magnetorheological (MR) dampers exhibit a significant time lag in their force–response to voltage inputs, reducing the efficacy of typical controllers designed for smaller scale devices where the lag is negligible. A new control algorithm is presented for large-scale MR devices that uses over-driving and back-driving of the commands to overcome the challenges associated with the dynamics of these large-scale MR dampers. An illustrative numerical example is considered to demonstrate the controller performance. Via simulations of the structure using several seismic ground motions, the merits of the proposed control strategy to achieve reductions in various response parameters are examined and compared against several accepted control algorithms. Experimental evidence is provided to validate the improved capabilities of the proposed controller in achieving the desired control force levels. Through real-time hybrid simulation (RTHS), the proposed controllers are also examined and experimentally evaluated in terms of their efficacy and robust performance. The results demonstrate that the proposed control strategy has superior performance over typical control algorithms when paired with a large-scale MR damper, and is robust for structural control applications.

Modeling of a large-scale magneto-rheological damper for seismic hazard mitigation. Part II: Semi-active mode

SUMMARY Magneto-rheological (MR) dampers are a promising device for seismic hazard mitigation because their damping characteristics can be varied adaptively using an appropriate control law. During the last few decades researchers have investigated the behavior of MR dampers and semi-active control laws associated with these types of dampers for earthquake hazard mitigation. A majority of this research has involved small-scale MR dampers. To investigate the dynamic behavior of a large-scale MR damper, characterization tests were conducted at the Lehigh Network for Earthquake Engineering Simulation equipment site on large-scale MR dampers. A new MR damper model, called the Maxwell Nonlinear Slider (MNS) model, is developed based on the characterization tests and is reported in this paper. The MNS model can independently describe the pre-yield and post-yield behavior of an MR damper, which makes it easy to identify the model parameters. The MNS model utilizes Hershel–Bulkley visco-plasticity to describe the post-yield non-Newtonian fluid behavior, that is, shear thinning and thickening behavior, of the MR fluid that occurs in the dampers. The predicted response of a large-scale damper from the MNS model along with that from existing Bouc–Wen and hyperbolic tangent models, are compared with measured response from various experiments. The comparisons show that the MNS model achieves better accuracy than the existing models in predicting damper response under cyclic loading. Copyright © 2012 John Wiley & Sons, Ltd.

A fully dynamic magneto-rheological fluid damper model

Control devices can be used to dissipate the energy of a civil structure subjected to dynamic loading, thus reducing structural damage and preventing failure. Semiactive control devices have received significant attention in recent years. The magneto-rheological (MR) fluid damper is a promising type of semiactive device for civil structures due to its mechanical simplicity, inherent stability, high dynamic range, large temperature operating range, robust performance, and low power requirements. The MR damper is intrinsically nonlinear and rate-dependent, both as a function of the displacement across the MR damper and the command current being supplied to the MR damper. As such, to develop control algorithms that take maximum advantage of the unique features of the MR damper, accurate models must be developed to describe its behavior for both displacement and current. In this paper, a new MR damper model that includes a model of the pulse-width modulated (PWM) power amplifier providing current to the damper, a proposed model of the time varying inductance of the large-scale 200 kN MR dampers coils and surrounding MR fluid—a dynamic behavior that is not typically modeled—and a hyperbolic tangent model of the controllable force behavior of the MR damper is presented. Validation experimental tests are conducted with two 200 kN large-scale MR dampers located at the Smart Structures Technology Laboratory (SSTL) at the University of Illinois at Urbana-Champaign and the Lehigh University Network for Earthquake Engineering Simulation (NEES) facility. Comparison with experimental test results for both prescribed motion and current and real-time hybrid simulation of semiactive control of the MR damper shows that the proposed MR damper model can accurately predict the fully dynamic behavior of the large-scale 200 kN MR damper.

Model-Based Feedforward-Feedback Actuator Control for Real-Time Hybrid Simulation

Substructure hybrid simulation is a powerful, cost-effective alternative for testing structural systems, closely coupling numerical simulation and experimental testing to obtain the complete response of a structure. In this approach, well-understood components of the structure are modeled numerically, while the components of interest are tested physically. Generally, an arbitrary amount of time may be used to calculate and apply displacements at each step of the hybrid simulation. However, when the rate-dependent behavior of the physical specimen is important, real-time hybrid simulation (RTHS) must be used. Computation, communication, and servohydraulic actuator limitations cause delays and lags that lead to inaccuracies and potential instabilities in RTHS. This paper proposes a new model-based servohydraulic tracking control method including feedforward-feedback links to achieve accurate tracking of a desired displacement in real time. The efficacy of the proposed approach is demonstrated through RTHS for a single-degree-of-freedom system and a 9-story steel building, each using a 200-kN large-scale magnetorheological damper as the rate-dependent physical specimen.

Parameter identification of large-scale magnetorheological dampers in a benchmark building

Magnetorheological (MR) dampers are devices that can be used for vibration reduction in structures. However, to use these devices in an effective way, a precise modeling is required. In this sense, in this paper we consider a modified parameter identification method of large-scale magnetorheological dampers which are represented using the normalized Bouc-Wen model. The main benefit of the proposed identification algorithm is the accuracy of the parameter estimation. The validation of the parameter identification method has been carried out using a black box model of an MR damper in a smart base-isolated benchmark building. Magnetorheological dampers are used in this numerical platform both as isolation bearings as well as semi-active control devices.

Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation system and its key technique

A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers. This paper proposes a roof magnetorheological (MR) intelligent isolation system to prevent the seismic whipping effect on machinery structures. Theoretically, the dynamic models of MR damper and the mechanical model of ship lift was established, the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced. Experimentally, the experimental model of the ship lift was given, the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared. In practical aspect, the large-scale MR damper (500 kN) and a sliding support with limited stiffness were designed and fabricated. It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.

Simplified inverse dynamics models for MR fluid dampers

The magnetorheological (MR) damper is considered to be one of the most promising semi-active control devices for reduction of structural vibration. Due to the damper’s nonlinear characteristics, its inverse dynamics model is difficult to obtain. In this paper, a simplified approach, namely the simplified inverse dynamics (SID) model, has been developed for both the Bingham plasticity model and the Bouc–Wen hysteresis model. SID models have then been used to calculate the optimal fluid yield stress or input current, in order to realize the desirable control forces obtained from various optimal control algorithms. For each model, a piston velocity feedback (PVF) algorithm and a damper force feedback (DFF) algorithm have been formulated. The proposed model has been shown to be applicable to both small-scale and large-scale MR dampers. Also, different configurations of MR dampers, such as ones with different dimensions, coil resistances, types of MR fluid, have been employed to show the generic nature of the SID model. The effectiveness of force tracking using the SID model has been demonstrated through a series of numerical simulations. A multi-storey frame structure with MR damper–brace systems, using a large-scale 20-ton MR damper, has been adopted. Numerical results show that the MR damper with the proposed SID model can produce forces very close to the optimal control forces, and that the response reduction is very close to that for the case of fully active control. Also, equally high accuracy of force tracking for different shaking levels and frequency contents of ground motions can be observed. The results demonstrate that the SID model can be a simple, yet effective, tool for both research and application purposes.