The Experts below are selected from a list of 8106 Experts worldwide ranked by ideXlab platform
Seung-bok Choi - One of the best experts on this subject based on the ideXlab platform.
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Design and Damping Force characterization of a new magnetorheological damper activated by permanent magnet flux dispersion
Smart Materials and Structures, 2017Co-Authors: Seung-bok ChoiAbstract:This work proposes a novel type of tunable magnetorheological (MR) damper operated based solely on the location of a permanent magnet incorporated into the piston. To create a larger Damping Force variation in comparison with the previous model, a different design configuration of the permanent-magnet-based MR (PMMR) damper is introduced to provide magnetic flux dispersion in two magnetic circuits by utilizing two materials with different magnetic reluctance. After discussing the design configuration and some advantages of the newly designed mechanism, the magnetic dispersion principle is analyzed through both the formulated analytical model of the magnetic circuit and the computer simulation based on the magnetic finite element method. Sequentially, the principal design parameters of the damper are determined and fabricated. Then, experiments are conducted to evaluate the variation in Damping Force depending on the location of the magnet. It is demonstrated that the new design and magnetic dispersion concept are valid showing higher Damping Force than the previous model. In addition, a curved structure of the two materials is further fabricated and tested to realize the linearity of the Damping Force variation.
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Damping Force tracking control of mr damper system using a new direct adaptive fuzzy controller
Shock and Vibration, 2015Co-Authors: Xuan Phu Do, Kruti Shah, Seung-bok ChoiAbstract:This paper presents a new direct adaptive fuzzy controller and its effectiveness is verified by investigating the Damping Force tracking control of magnetorheological (MR) fluid based damper (MR damper in short) system. In the formulation of the proposed controller, a model of interval type 2 fuzzy controller is combined with the direct adaptive control to achieve high performance in vibration control. In addition, (H infinity) tracking technique is used in building a model of the direct adaptive fuzzy controller in which an enhanced iterative algorithm is combined with the fuzzy model. After establishing a closed-loop control structure to achieve high control performance, a cylindrical MR damper is adopted and Damping Force tracking results are obtained and discussed. In addition, in order to demonstrate the effectiveness of the proposed control strategy, two existing controllers are modified and tested for comparative work. It has been demonstrated from simulation and experiment that the proposed control scheme provides much better control performance in terms of Damping Force tracking error. This leads to excellent vibration control performance of the semiactive MR damper system associated with the proposed controller.
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Magnetorheology of a Carbonyliron Microsphere Suspension with a Halloysite Additive and Its Damping Force Characteristics
Industrial & Engineering Chemistry Research, 2015Co-Authors: Seung Hyuk Kwon, Seung-bok Choi, Cheng Hai Hong, Phu Xuan, Hyoung Jin ChoiAbstract:A carbonyliron (CI)-based magnetorheological (MR) suspension was prepared with halloysite nanoclay particles as an additive. The MR properties of the suspension were investigated using a rotational rheometer with a parallel-plate geometry equipped with a magnetic field supply under a range of external magnetic field strengths. From the sedimentation ratio test to assess the dispersion stability, the addition of halloysite particles to the CI suspension was found to improve the sedimentation problem. MR fluids containing both pure CI and CI/halloysite were employed in a custom-designed MR damper, and their Damping characteristics, such as the Damping Force as a function of time, displacement, and velocity, were examined experimentally because the vibration attenuation using mechanical damper systems is one of the main applications of MR fluids. Under the same magnetic field strength, the Damping characteristics of the two MR fluids were found to be related directly to their yield stresses.
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design of a new adaptive fuzzy controller and its implementation for the Damping Force control of a magnetorheological damper
Smart Materials and Structures, 2014Co-Authors: Kruti Shah, Seung-bok ChoiAbstract:This paper presents a new adaptive fuzzy controller and its implementation for the Damping Force control of a magnetorheological (MR) fluid damper in order to validate the effectiveness of the control performance. An interval type 2 fuzzy model is built, and then combined with modified adaptive control to achieve the desired Damping Force. In the formulation of the new adaptive controller, an enhanced iterative algorithm is integrated with the fuzzy model to decrease the time of calculation (D Wu 2013 IEEE Trans. Fuzzy Syst. 21 80–99) and the control algorithm is synthesized based on the tracking technique. In addition, for the verification of good control performance of the proposed controller, a cylindrical MR damper which can be applied to the vibration control of a washing machine is designed and manufactured. For the operating fluid, a recently developed plate-like particle-based MR fluid is used instead of a conventional MR fluid featuring spherical particles. To highlight the control performance of the proposed controller, two existing adaptive fuzzy control algorithms proposed by other researchers are adopted and altered for a comparative study. It is demonstrated from both simulation and experiment that the proposed new adaptive controller shows better performance of Damping Force control in terms of response time and tracking accuracy than the existing approaches.
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optimal design of high Damping Force engine mount featuring mr valve structure with both annular and radial flow paths
Smart Materials and Structures, 2013Co-Authors: Quoc Hung Nguyen, Seung-bok ChoiAbstract:This paper focuses on the optimal design of a compact and high Damping Force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high Damping Force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum Damping Force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the 'lockup' problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting Damping Force and power consumption.
Ou Jin-ping - One of the best experts on this subject based on the ideXlab platform.
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Damping Force hysteresis loop models for X type and triangle mild steel dampers(I) ——Based on double linear constitutive model
World Information On Earthquake Engineering, 2020Co-Authors: Ou Jin-pingAbstract:Based on double linear constitutive model of mild steel,Damping Force hysteresis loop models of the X-type and the triangle type mild steel dampers are derived from classic mechanical principle directly. Firstly, the relationship and its asymptote between Force and displacement of the steel plate damper are deduced under monotonic loading. Secondly, Damping Force hysteresis loop models for mild steel plate damper are deduced under considering the ideal elastic-plastic model and the linear hardening model respectively. Finally, the comparison of theory and experiment is carried out,and the effectiveness of theoretical models is verified. Moreover, the reason of errors is analyzed.
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Damping Force hysteresis loop models for X type and triangle mild steel dampers(II) ——based on Ramberg-Osgood constitutive model
World Information On Earthquake Engineering, 2020Co-Authors: Ou Jin-pingAbstract:Based on Ramberg-Osgood constitutive model (R-O model) of mild steel, Damping Force hysteresis loop models of X type and triangle mild steel dampers are derived from classic mechanical principle directly. Firstly, the R-O stress-strain relationship of mild steel is given under cyclic loading. Secondly, Damping Force hysteresis loop models for mild steel plate damper are deduced under considering the R-O constitutive model. Finally, the comparison of R-O model and experiment and double linear model is carried out. And then the effectiveness of this model is verified. Moreover, the reason of errors is analyzed.
Mitsuji Sampei - One of the best experts on this subject based on the ideXlab platform.
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Suppression of Vertical Vibration in Railway Vehicles by Damping Force Control of Primary Suspension Using an LQG Controller
Journal of System Design and Dynamics, 2020Co-Authors: Yoshiki Sugahara, Tadao Takigami, Akihito Kazato, Reiko Koganei, Mitsuji SampeiAbstract:Suppression of the vertical bending vibration of carbodies has recently become essential in improving the ride comfort of railway vehicles. In this paper, we propose a method of controlling vibration in the primary suspension of rolling stock to reduce carbody vibration. Systems conceivable for this purpose include a semi-active suspension system with variable axle dampers that can control Damping Force continuously by command current to the Damping Force control valve. Based on LQG control theory, we carried out numerical simulations and performed excitation testing with a carbody equivalent to an actual Shinkansen vehicle fitted with variable axle dampers to selectively suppress the first mode bending vibration of the carbody. The results show that this LQG control method reduces the power spectral density (PSD) of acceleration on the floor more effectively than the sky-hook control method, which does not consider the vibration modes of the carbody.
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vertical vibration suppression of railway vehicle by primary suspension Damping Force control results of running tests using shinkansen vehicle
Transactions of the Japan Society of Mechanical Engineers. C, 2008Co-Authors: Yoshiki Sugahara, Akihito Kazato, Takahiro Tomioka, Mitsuji SampeiAbstract:Suppression of the vertical bending vibration of carbodies has recently become an essential issue to improve the ride comfort of railway vehicles. For suppressing this vibration, the primary suspension Damping Force control system with variable axle damper is being developed, which can control its Damping Force continuously by command current to the Damping Force control valve. This paper reports the results of numerical simulations for running test applying this system to Shinkansen vehicle, and the results of the running test on Sanyo-Shinkansen line using an actual Shinkansen vehicle fitted with newly-developed variable axle dampers. The control algorithm which controls axle dampers is based on skyhook control theory in one case and LQG control theory in another case. The results of both the simulations and the running tests demonstrate that the vertical vibration of the trucks and the carbody decreased. In the running tests in particular, the system reduced the vertical vibration acceleration PSD peak value due to the natural vibration in the first bending mode by almost 20% compared with the case of using conventional passive axle dampers. As the result, the value of ride quality level (Lr) was reduced by about 3 dB or more.
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suppressing vertical vibration in railway vehicles through primary suspension Damping Force control
Journal of System Design and Dynamics, 2007Co-Authors: Yoshiki Sugahara, Tadao Takigami, Mitsuji SampeiAbstract:Suppression of the vertical bending vibration of carbodies has recently become essential in improving the riding comfort of railway vehicles. In many cases, the resonant frequency of the system (consisting of a bogie frame and axle springs) is close to that of the first mode bending vibration of the carbody, so suppressing the vibration of bogie frames near their resonant frequency effectively reduces carbody vibration. In this paper, we propose a method of suppressing such vibration by controlling the Damping Force of axle dampers installed between bogie frames and wheel sets. The design of the semi-active controller applied to determine the optimal Damping Force is based on the sky hook control theory. Numerical simulations using a vehicle model with 16 degrees of freedom as well as excitation tests using a carbody with variable axle dampers at a rolling stock test plant were carried out. The results show that this control method effectively reduces the power spectral density (PSD) of acceleration on the floor and that the riding comfort level (LT) can be improved by about 3 dB.
Quoc Hung Nguyen - One of the best experts on this subject based on the ideXlab platform.
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optimal design of high Damping Force engine mount featuring mr valve structure with both annular and radial flow paths
Smart Materials and Structures, 2013Co-Authors: Quoc Hung Nguyen, Seung-bok ChoiAbstract:This paper focuses on the optimal design of a compact and high Damping Force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high Damping Force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum Damping Force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the 'lockup' problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting Damping Force and power consumption.
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Geometric optimal design of MR damper considering Damping Force, control energy and time constant
Journal of Physics: Conference Series, 2009Co-Authors: Quoc Hung Nguyen, Seung-bok ChoiAbstract:This paper presents an optimal design of magnetorheological (MR) damper based on finite element analysis. The MR damper is constrained in a specific volume and the optimization problem identifies geometric dimensions of the damper that minimizes an objective function. The objective function is proposed by considering the Damping Force, dynamic range and the inductive time constant of the damper. After describing the configuration of the MR damper, a quasi-static modelling of the damper is performed based on Bingham model of MR fluid. The initial geometric dimensions of the damper are then determined based on the assumption of constant magnetic flux density throughout the magnetic circuit of the damper. Subsequently, the optimal design variables that minimize the objective function are determined using a golden-section algorithm and a local quadratic fitting technique via commercial finite element method parametric design language. A comparative work on Damping Force and time constant between the initial and optimal design is undertaken.
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optimal design of a vehicle magnetorheological damper considering the Damping Force and dynamic range
Smart Materials and Structures, 2009Co-Authors: Quoc Hung Nguyen, Seung-bok ChoiAbstract:This paper presents an optimal design of a passenger vehicle magnetorheological (MR) damper based on finite element analysis. The MR damper is constrained in a specific volume and the optimization problem identifies the geometric dimensions of the damper that minimize an objective function. The objective function consists of the Damping Force, the dynamic range, and the inductive time constant of the damper. After describing the configuration of the MR damper, the Damping Force and dynamic range are obtained on the basis of the Bingham model of an MR fluid. Then, the control energy (power consumption of the damper coil) and the inductive time constant are derived. The objective function for the optimization problem is determined based on the solution of the magnetic circuit of the initial damper. Subsequently, the optimization procedure, using a golden-section algorithm and a local quadratic fitting technique, is constructed via commercial finite element method parametric design language. Using the developed optimization tool, optimal solutions of the MR damper, which are constrained in a specific cylindrical volume defined by its radius and height, are determined and a comparative work on Damping Force and inductive time constant between the initial and optimal design is undertaken.
Sunil K. Agrawal - One of the best experts on this subject based on the ideXlab platform.
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Variable Damping Force Tunnel for Gait Training Using ALEX III
IEEE Robotics and Automation Letters, 2017Co-Authors: Paul Stegall, Damiano Zanotto, Sunil K. AgrawalAbstract:Haptic feedback not only affects the quality of training but can also influence the physical design of robotic gait trainers by determining how much Force needs to be applied to the user and the nature of the Force. This letter presents the design of a variable Damping Force tunnel and explores the effect of the shape and strength of the Damping field using ALEX III, a treadmill-based exoskeleton developed at Columbia University. The study consists of 32 healthy subjects who were trained for 40 min in the device. The subjects were trained to follow a footpath with a 50% increase in step height, so the foot would have 1.5 times the ground clearance. Subjects were assigned to one of four groups: linear high, linear low, parabolic high, and parabolic low. Linear or parabolic denotes the shape of the Damping field, and high or low denotes the rate of change (strength) of the field based on error. It is shown that the new controller is capable of inducing gait adaptations in healthy individuals while walking in the device. All groups showed adaptations in step height, while only the high strength groups showed changes in normalized error area, a measure of how closely the desired path was followed.
