The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achie...The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achieve this,a bidirectional adjustable MRF damper was designed and developed.Magnetic field simulation analysis was conducted on the damper,along with simulation analysis on its dynamic characteristics.The dynamic characteristics were ultimately validated through experimental testing on the material testing machine,thereby corroborating the theoretical simulation results.Concurrently,this process generated valuable test data for subsequent implementation of the semi-active vibration control system.The simulation and test results demonstrate that the integrated permanent magnet effectively accomplishes bidirectional regulation.The magnetic induction intensity of the damping channel is 0.2 T in the absence of current,increases to 0.5 T when a maximum forward current of 4 A is applied,and becomes 0 T when a maximum reverse current of 3.8 A is applied.When the excitation amplitude is 8 mm and the frequency is 2 Hz,with the applied currents varying,the maximum damping force reaches 8 kN,while the minimum damping force measures at 511 N.Additionally,at zero current,the damping force stands at 2 kN,which aligns closely with simulation results.The present paper can serve as a valuable reference for the design and research of semi-active MRF dampers.展开更多
The theoretical study of a semi-active predictive control(SAPC) system with magnetorheological(MR) dampers to reduce the responses of seismically excited structures was presented.The SAPC scheme is based on a predicti...The theoretical study of a semi-active predictive control(SAPC) system with magnetorheological(MR) dampers to reduce the responses of seismically excited structures was presented.The SAPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an object function,which has a function of self-compensation for time delay occurring in real application.A double-ended shear mode combined with a valve mode MR damper,named MRF-04K damper,with the maximum force of 20 kN was designed and manufactured,and parameters of the Bouc-Wen hysteresis model were determined to portray the behavior of this damper.As an example,a 5-story building frame equipped with 2 MRF-04K dampers was presented to demonstrate the performance of the proposed SAPC scheme for addressing time delay and reducing the structural responses under different earthquakes.Comparison with the uncontrolled structure,the passive-off and passive-on cases indicates that both the peak and the norm values of structural responses are all clearly reduced,and the SAPC scheme has a better performance than the two passive cases.展开更多
The behavior of viscous fluid damper applied in coupling structures subjected to near-fault earthquake was studied.The structural nonlinearity was characterized by Bouc-Wen model and several near-fault ground motions ...The behavior of viscous fluid damper applied in coupling structures subjected to near-fault earthquake was studied.The structural nonlinearity was characterized by Bouc-Wen model and several near-fault ground motions were simulated by the combination of a recorded earthquake(background ground motion) with equivalent velocity pulses that possess near-fault features.Extensive parametric studies were carried out to find the appropriate damping coefficient.Performances of viscous fluid dampers were demonstrated by the relationship between the force and displacement,the maximal damper force and stroke.The control performances were demonstrated in terms of the response reductions of adjacent structures.The results show that the dynamic responses of adjacent structures are mitigated greatly.Proper damping coefficients of connecting fluid dampers have a small difference,while adjacent structures under different near-fault ground motions with the same peak acceleration.The maximum force of damper is about 0.8 MN,and the maximum damper stroke is about ±550 mm.Satisfied viscous fluid dampers can be produced according to the current manufacturing skills.展开更多
This work addresses the problem of self-excited vibration,which degrades the stability of the levitation control,decreases the ride comfort,and restricts the construction cost of maglev system.Firstly,a minimum model ...This work addresses the problem of self-excited vibration,which degrades the stability of the levitation control,decreases the ride comfort,and restricts the construction cost of maglev system.Firstly,a minimum model containing a flexible bridge and a single levitation unit is presented.Based on the simplified model,the principle underlying the self-excited vibration is explored.After investigations about the energy transmission between the levitation system and bridge,it is concluded that the increment of modal damping can dissipate the accumulated energy by the bridge and the self-excited vibration may be avoided.To enlarge the equivalent modal damping of bridge,the sky-hooked damper is adopted.Furthermore,to avoid the hardware addition of real sky-hooked damper,considering the fact that the electromagnet itself is an excellent actuator that is capable of providing sufficiently fast and large force acting on the bridge to emulate the influence of the real sky-hooked damper,the technique of the virtual sky-hooked damper is proposed.The principle underlying the virtual sky-hooked damper by electromagnet is explored and the vertical velocity of bridge is estimated.Finally,numerical and experimental results illustrating the stability improvement of the vehicle-bridge interaction system are provided.展开更多
In order to improve the screening efficiency of vibrating screen and make vibration process smooth,a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during...In order to improve the screening efficiency of vibrating screen and make vibration process smooth,a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during the test were collected. The trispectrum model of autoregressive (AR) time series was built and the correlation dimension was used to quantify the fractal characteristics during the vibration process. The result shows that,in different working conditions,trispectrum slices are applied to obtaining the information of non-Gaussian,nonlinear amplitude?frequency characteristics of the signal. Besides,there is correlation between the correlation dimension of vibration signal and trispectrum slices,which is very important to select the optimum working parameters of the MR damper and vibrating screen. And in the experimental conditions,it is found that when the working current of MR damper is 2 A and the rotation speed of vibration motor is 800 r/min,the vibration screen reaches its maximum screening efficiency.展开更多
The passive suspension system of tracked vehicle is designed to get its suspension parameters based on a certain common velocity and a certain road surface roughness. Its performance optimization only exists in a cert...The passive suspension system of tracked vehicle is designed to get its suspension parameters based on a certain common velocity and a certain road surface roughness. Its performance optimization only exists in a certain operating mode without far-ranging adaptability. Holding the damper basic frame form and applying semi-active suspension system based on MR (magnetorheological) damper, the vehicle can keep its optimum efficiency between energy dissipation and vibration reduction in all kinds of operating modes. Theoretical analysis and experiments show that the damping performances provided by this MRF(magnetorheological fluids) vane damper are same as those provided by traditional damper, and the new damper has the better controllability and adaptability.展开更多
A semi-active magneto-rheological （MR） damper was experimentally investigated and compared to an original equipment manufacturer （OEM） damper for a passenger vehicle, by using a quarter car models. A full-scale tw...A semi-active magneto-rheological （MR） damper was experimentally investigated and compared to an original equipment manufacturer （OEM） damper for a passenger vehicle, by using a quarter car models. A full-scale two-degree-of-freedom quarter car experimental set-up was constructed to study the vehicle suspension. On-off skyhook controller and Fuzzy-Lyapunov skyhook controller （FLSC） were employed to control the input current for MR damper so as to achieve the desired damping force. Tests were done to evaluate the ability of MR damper for controlling vehicle vibration. Test results show that the semi-active MR vehicle suspension vibration control system is feasible. In comparison with OEM damper, on-off and FLSC controlled MR dampers can effectively reduce the acceleration of vehicle sprtmg mass by about 15% and 24%, respectively.展开更多
Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper ...Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper with fail-safe capability is designed.Firstly,the mathematical model of damping moment is deduced based on the parallel-plate model and Bingham model of MR fluids.Secondly,some influence factors of damping adjustable multiple are analyzed to provide some ways for augmenting the damping adjustable multiple under the condition of keeping initial damping moment invariable.Finally,the magnetic circuit is designed,and magnetic field distribution is simulated with the magnetic finite element analysis software-ANSOFT.The theory and simulation results confirm that the damping adjustable range of vane MRF damper can meet the requirement of heavy vehicle semi-active suspension system.展开更多
为了对半潜式风机水平向和竖向的振动进行控制,提出了多向多点位调谐质量阻尼器(tuned mass damper,TMD)的布设方式,即在机舱内布置H-TMD,平台内布置V-TMD。为研究这种TMD布设方式的减振效果,建立了半潜式风机-多向多点位TMD全耦合数值...为了对半潜式风机水平向和竖向的振动进行控制,提出了多向多点位调谐质量阻尼器(tuned mass damper,TMD)的布设方式,即在机舱内布置H-TMD,平台内布置V-TMD。为研究这种TMD布设方式的减振效果,建立了半潜式风机-多向多点位TMD全耦合数值模型,利用OpenFAST仿真分析风浪联合作用下半潜式风机的动力响应。结果表明:布置多向多点位TMD的减振效果要比单点位TMD的减振效果要好,且在机舱内布置低频H-TMD,平台内布置V-TMD为最优布置方案,能够使半潜式风机纵摇、横摇、垂荡、塔架纵向振动的平均标准差控制率分别达到13.97%、32.85%、15.21%、2.86%。展开更多
文摘The aim of this study is to address the issues associated with traditional magnetorheological fluid(MRF)dampers,such as insufficient damping force after power failure and susceptibility to settlement.In order to achieve this,a bidirectional adjustable MRF damper was designed and developed.Magnetic field simulation analysis was conducted on the damper,along with simulation analysis on its dynamic characteristics.The dynamic characteristics were ultimately validated through experimental testing on the material testing machine,thereby corroborating the theoretical simulation results.Concurrently,this process generated valuable test data for subsequent implementation of the semi-active vibration control system.The simulation and test results demonstrate that the integrated permanent magnet effectively accomplishes bidirectional regulation.The magnetic induction intensity of the damping channel is 0.2 T in the absence of current,increases to 0.5 T when a maximum forward current of 4 A is applied,and becomes 0 T when a maximum reverse current of 3.8 A is applied.When the excitation amplitude is 8 mm and the frequency is 2 Hz,with the applied currents varying,the maximum damping force reaches 8 kN,while the minimum damping force measures at 511 N.Additionally,at zero current,the damping force stands at 2 kN,which aligns closely with simulation results.The present paper can serve as a valuable reference for the design and research of semi-active MRF dampers.
基金Projects(90815025,51178034) supported by the National Natural Science Foundation of China
文摘The theoretical study of a semi-active predictive control(SAPC) system with magnetorheological(MR) dampers to reduce the responses of seismically excited structures was presented.The SAPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an object function,which has a function of self-compensation for time delay occurring in real application.A double-ended shear mode combined with a valve mode MR damper,named MRF-04K damper,with the maximum force of 20 kN was designed and manufactured,and parameters of the Bouc-Wen hysteresis model were determined to portray the behavior of this damper.As an example,a 5-story building frame equipped with 2 MRF-04K dampers was presented to demonstrate the performance of the proposed SAPC scheme for addressing time delay and reducing the structural responses under different earthquakes.Comparison with the uncontrolled structure,the passive-off and passive-on cases indicates that both the peak and the norm values of structural responses are all clearly reduced,and the SAPC scheme has a better performance than the two passive cases.
基金Project(50778077) supported by the National Natural Science Foundation of ChinaProject(50925828) supported by the National Science Foundation for Distinguished Young Scholars of China
文摘The behavior of viscous fluid damper applied in coupling structures subjected to near-fault earthquake was studied.The structural nonlinearity was characterized by Bouc-Wen model and several near-fault ground motions were simulated by the combination of a recorded earthquake(background ground motion) with equivalent velocity pulses that possess near-fault features.Extensive parametric studies were carried out to find the appropriate damping coefficient.Performances of viscous fluid dampers were demonstrated by the relationship between the force and displacement,the maximal damper force and stroke.The control performances were demonstrated in terms of the response reductions of adjacent structures.The results show that the dynamic responses of adjacent structures are mitigated greatly.Proper damping coefficients of connecting fluid dampers have a small difference,while adjacent structures under different near-fault ground motions with the same peak acceleration.The maximum force of damper is about 0.8 MN,and the maximum damper stroke is about ±550 mm.Satisfied viscous fluid dampers can be produced according to the current manufacturing skills.
基金Projects(11302252,11202230) supported by the National Natural Science Foundation of China
文摘This work addresses the problem of self-excited vibration,which degrades the stability of the levitation control,decreases the ride comfort,and restricts the construction cost of maglev system.Firstly,a minimum model containing a flexible bridge and a single levitation unit is presented.Based on the simplified model,the principle underlying the self-excited vibration is explored.After investigations about the energy transmission between the levitation system and bridge,it is concluded that the increment of modal damping can dissipate the accumulated energy by the bridge and the self-excited vibration may be avoided.To enlarge the equivalent modal damping of bridge,the sky-hooked damper is adopted.Furthermore,to avoid the hardware addition of real sky-hooked damper,considering the fact that the electromagnet itself is an excellent actuator that is capable of providing sufficiently fast and large force acting on the bridge to emulate the influence of the real sky-hooked damper,the technique of the virtual sky-hooked damper is proposed.The principle underlying the virtual sky-hooked damper by electromagnet is explored and the vertical velocity of bridge is estimated.Finally,numerical and experimental results illustrating the stability improvement of the vehicle-bridge interaction system are provided.
基金Project(50975098) supported by the National Natural Science Foundation of ChinaProject(2008HZ0002-1) supported by the Major Scientific and Technological Program of Fujian Province,China
文摘In order to improve the screening efficiency of vibrating screen and make vibration process smooth,a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during the test were collected. The trispectrum model of autoregressive (AR) time series was built and the correlation dimension was used to quantify the fractal characteristics during the vibration process. The result shows that,in different working conditions,trispectrum slices are applied to obtaining the information of non-Gaussian,nonlinear amplitude?frequency characteristics of the signal. Besides,there is correlation between the correlation dimension of vibration signal and trispectrum slices,which is very important to select the optimum working parameters of the MR damper and vibrating screen. And in the experimental conditions,it is found that when the working current of MR damper is 2 A and the rotation speed of vibration motor is 800 r/min,the vibration screen reaches its maximum screening efficiency.
文摘The passive suspension system of tracked vehicle is designed to get its suspension parameters based on a certain common velocity and a certain road surface roughness. Its performance optimization only exists in a certain operating mode without far-ranging adaptability. Holding the damper basic frame form and applying semi-active suspension system based on MR (magnetorheological) damper, the vehicle can keep its optimum efficiency between energy dissipation and vibration reduction in all kinds of operating modes. Theoretical analysis and experiments show that the damping performances provided by this MRF(magnetorheological fluids) vane damper are same as those provided by traditional damper, and the new damper has the better controllability and adaptability.
基金Project(51175265) supported by the National Natural Science Foundation of ChinaProject(CX10B_114Z) supported by Jiangsu College Graduate Research and Innovation Program,China+1 种基金Project(BK2008415) supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(Y1110313) supported by the Natural Science Foundation of Zhejiang Province,China
文摘A semi-active magneto-rheological （MR） damper was experimentally investigated and compared to an original equipment manufacturer （OEM） damper for a passenger vehicle, by using a quarter car models. A full-scale two-degree-of-freedom quarter car experimental set-up was constructed to study the vehicle suspension. On-off skyhook controller and Fuzzy-Lyapunov skyhook controller （FLSC） were employed to control the input current for MR damper so as to achieve the desired damping force. Tests were done to evaluate the ability of MR damper for controlling vehicle vibration. Test results show that the semi-active MR vehicle suspension vibration control system is feasible. In comparison with OEM damper, on-off and FLSC controlled MR dampers can effectively reduce the acceleration of vehicle sprtmg mass by about 15% and 24%, respectively.
基金the National Defence Sci-Tech Key Lab Fundation(51457040204BQ0102)
文摘Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper with fail-safe capability is designed.Firstly,the mathematical model of damping moment is deduced based on the parallel-plate model and Bingham model of MR fluids.Secondly,some influence factors of damping adjustable multiple are analyzed to provide some ways for augmenting the damping adjustable multiple under the condition of keeping initial damping moment invariable.Finally,the magnetic circuit is designed,and magnetic field distribution is simulated with the magnetic finite element analysis software-ANSOFT.The theory and simulation results confirm that the damping adjustable range of vane MRF damper can meet the requirement of heavy vehicle semi-active suspension system.
文摘为了对半潜式风机水平向和竖向的振动进行控制,提出了多向多点位调谐质量阻尼器(tuned mass damper,TMD)的布设方式,即在机舱内布置H-TMD,平台内布置V-TMD。为研究这种TMD布设方式的减振效果,建立了半潜式风机-多向多点位TMD全耦合数值模型,利用OpenFAST仿真分析风浪联合作用下半潜式风机的动力响应。结果表明:布置多向多点位TMD的减振效果要比单点位TMD的减振效果要好,且在机舱内布置低频H-TMD,平台内布置V-TMD为最优布置方案,能够使半潜式风机纵摇、横摇、垂荡、塔架纵向振动的平均标准差控制率分别达到13.97%、32.85%、15.21%、2.86%。
