Using magnetorheological (MR) fluids in hydraulic engine mount for damping vehicle noise and vibration is opposed firstly, the structure of passive type and its mechanical model are described. The analysis of the expe...Using magnetorheological (MR) fluids in hydraulic engine mount for damping vehicle noise and vibration is opposed firstly, the structure of passive type and its mechanical model are described. The analysis of the experimental data show that the dynamic characteristics of MR mount such as dynamic stiffness and loss angles vary distinctly as the excitation frequency, and MR fluids as one type of attracting controllable fluids are fit for hydraulic engine mounts. The author advises to work out potentialities of MR fluids, the semi control or active control MR fluids filled hydraulic engine mount must be developed.展开更多
Magnetorheological (MR) fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic...Magnetorheological (MR) fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic field, which is known as MR effect, resulting in variation of stiffness, shear modulus, damping and tribological characteristics of MR fluid. As MR effect depends on the density of particles in the fluid or the strength of a magnetic field, the experiments are conducted to evaluate the friction property under reciprocating motion by changing the types of MR fluid and the strength of a magnetic field. The material of aluminum, brass, and steel are chosen for specimen as they are the most common material in mechanical applications. The surfaces of specimen are also observed by optical microscope before and after experiments to compare the surfaces with test conditions. The comparing results show that the friction coefficient increases as the strength of a magnetic field increases in regardless of types of MR fluid or the material. Also the density of particle in MR fluid affects the friction characteristic. The results from this research can be used to improve the performance of mechanical applications using MR fluid.展开更多
The aim of this work is to analyze and design a control system for vibration reduction in a rotor system using a shear mode magnetorheological fluid(MRF)damper.A dynamic model of the MRF damper-rotor system was built ...The aim of this work is to analyze and design a control system for vibration reduction in a rotor system using a shear mode magnetorheological fluid(MRF)damper.A dynamic model of the MRF damper-rotor system was built and simulated in Matlab/Simulink to analyze the rotor vibration characteristics and the vibration reduction effect of the MRF damper.Based on the numerical simulation analysis,an optimizing control strategy using pattern search method was proposed and designed.The control system was constructed on a test rotor bench and experiment validations on the effectiveness of the proposed control strategy were conducted.Experimental results show that rotor vibration caused by unbalance can be well controlled whether in resonance region(70%)or in non-resonance region(30%).An irregular vibration amplitude jump can be suppressed with the optimization strategy.Furthermore,it is found that the rapidity of transient response and efficiency of optimizing technique depend on the pattern search step.The presented strategies and control system can be extended to multi-span(more than two or three spans)rotor system.It provides a powerful technical support for the extension and application in target and control for shafting vibration.展开更多
In order to study the squeeze-strengthening effect of silicone oil-based magnetorheological fluid (MRF), theoretical basis of disc squeezing brake was presented and a squeezing braking characteristics test-bed for M...In order to study the squeeze-strengthening effect of silicone oil-based magnetorheological fluid (MRF), theoretical basis of disc squeezing brake was presented and a squeezing braking characteristics test-bed for MRF was designed. Moreover, relevant experiments were carded out and the relationship between squeezing pressure and braking torque was proposed. Experiments results showed that the yield stress of MRF improved linearly with the increasing of external squeezing pressure and the braking torque increased three times when external squeezing pressure achieved 2 MPa.展开更多
The Bingham constitutive model, which is previously used in depiction of magnetorheological (MR) fluids rheological behaviors for design devices, exhibits discontinuous characteristics in representation of pre-yield...The Bingham constitutive model, which is previously used in depiction of magnetorheological (MR) fluids rheological behaviors for design devices, exhibits discontinuous characteristics in representation of pre-yield behaviors and post-yield behaviors. A Biviscous constitutive model is presented to depict rheological behaviors of MR fluids and design automotive shock absorber. Quasi-static flow equations of MR fluids in annular channels are set theoretically up based on Navier-Stokes equations and several rational simplifications are made. And both flow boundary conditions and flow compatibilities conditions are established. Meantime, analytical velocity profiles of MR fluids though annular channels are obtained via solution of the quasi-static flow equations using Biviscous constitutive model. The prediction methodology of damping force offered by MR fluid shock absorber is formulated and damping performances are predicated in order to determine design parameters. MR fluid shock absorber for Mazda 323 car suspension is designed and fabricated in Chongqing University, China. Measurements from sinusoidal displacement cycle by Shanchuan Shock Absorber Ltd. of China North Industry Corporation reveal that the analytical methodology and design theory are reasonable.展开更多
A pin-on-disc wear apparatus was used to carry out the tribological experiment of brass to investigate the effect of a magnetorheological (MR) fluid on the interfacial surface with and without magnetic field. A seri...A pin-on-disc wear apparatus was used to carry out the tribological experiment of brass to investigate the effect of a magnetorheological (MR) fluid on the interfacial surface with and without magnetic field. A series of tests were performed at the loads of 20-100 N and rotating speeds of 127-425 r/min for 2 h. The friction coefficient and wear rate were monitored by the wear apparatus, while the microstructures of the worn surfaces were observed by scanning electron microscope (SEM). In addition, the chemical composition of worn surfaces was analyzed by energy dispersive X-ray spectroscopy (EDS). Test results show different friction and wear performance of the MR fluid with and without magnetic field. At the same time, the effects of various normal loads and rotating speeds on the tribological behavior were investigated. Through the investigation of the morphologies of the wom surfaces under the magnetic field, it is found that the MR particles are clearly evident on the wom surface and the plastic flow of ridges causes the lateral extrusion. This directly indicates that abrasive wear is the predominant wear mechanism observed with MR fluid.展开更多
A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological (MRF) dampers is designed. A finite element model of the MRF damper- rotor system is built and used to a...A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological (MRF) dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled ( first critical speed region 37% , second critical speed region 42% ). To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.展开更多
In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45#...In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45# transformer oil,was finished.And characteristics of these samples were tested and analyzed.The results show that Tween-80 and Span-80 can improve the sedimentary stability,and the larger mass fraction can also increase the sedimentary stability.Using 45# transformer oil instead of special shock absorption fluid as a carrier of MRF,the shear yield stress remains nearly constant but the viscosity and the sedimentary stability are reduced.The MRF with diameter of 2.73 μm shows better sedimentary stability than that of the MRF with diameter of 2.30 μm,or 4.02 μm.Stearic acid obviously improves sedimentary stability and off-state viscosity,but has no function on the shear yield stress.In magnetic field of 237 kA/m,the shear yield stress of MRF based on special shock absorption fluid is 18.34 kPa and the shear yield stress of MRF based on 45# transformer oil is 14.26 kPa.展开更多
Based on the single-chain structure model of magnetorheological fluids, a formu la for the calculation of shear stresses was established. The interaction force of two magnetic particles in an infinite single-chain wa...Based on the single-chain structure model of magnetorheological fluids, a formu la for the calculation of shear stresses was established. The interaction force of two magnetic particles in an infinite single-chain was deduced using a new theoretical model which is founded on Ampere' molecular curr ent hypothesis, dipole theory and Ampere' law. Furthermore, the resultant force on a particle was then deduced by taking into account of the action caused by al l the other particles in the single-chain. A predictive formula for shear stres ses was made corresponding to the case that MR fluids were sheared by a small an gle and the calculating results fit well on the order with the yield stresses of the commercial MR fluids.展开更多
With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various param...With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various parameters on damping force characteristics. A mathematical model of the output damping force on the MRF damper is established by the mechanism modeling method,a first order output sensitivity equation is deduced and the expression of the first order output sensitivity function is obtained. The first-order sensitivity functions of ten design parameters are solved,and the influence degree of system parameters change on the output force of MRF damper is analyzed by comparing the sensitivity index of the parameters. Two sensitivities of vibration velocity and control current are obtained through experiment to prove the other parameters sensitivity analysis conclusion by analogy verification,which provides guidance for the structure optimization design of MRF damper.展开更多
To address the problem of flexible drive control of gastrointestinal(GI)tract micro-capsule robot posture,a novel dual helix magnetorheological fluid(MRF)micro-robot(DHMRFMR)is proposed and developed in this paper.Bas...To address the problem of flexible drive control of gastrointestinal(GI)tract micro-capsule robot posture,a novel dual helix magnetorheological fluid(MRF)micro-robot(DHMRFMR)is proposed and developed in this paper.Based on the mechanical properties of magnetorheological fluid,the relationship model of magnetic field force is obtained,and the thrust model is established.Double micro DC deceleration motor is used to drive the two ends of the helical actuator to make the DHMRFMR forward and backward,by changing the external magnetic field rotation speed,direction and distance,adjust the attitude direction of the robot.Numerical simulation software ANSYS is used to analyze the motion law of external fluid of DHMRFMR,and the visualization of fluid velocity and pressure distribution is realized.The front-end helix actuator can change the flow path of the fluid,and the middle and tail of the DHMRFMR bear less pressure,which improves the stability and flexibility of the robot.The novel DHMRFMR is suitable for internal drive in bending environment,and has a good application prospect in biomedical engineering field in human intestinal unstructured environment.展开更多
Isolator systems on ships should ideally be able to simultaneously reduce low frequency vibration response and high frequency shock response. Conventional isolator systems are unable to do so To solve the problem, a n...Isolator systems on ships should ideally be able to simultaneously reduce low frequency vibration response and high frequency shock response. Conventional isolator systems are unable to do so To solve the problem, a new style isolator system was created. This isolator system consists of a steel coil spring component and a magnetorheological (MR) damper component working in parallel. Experiments on this isolator system were carried out, including tests of vibration reduction and shock resistance. The vibration load frequencies were set from 1-15 Hz, and force amplitudes from 2.94-11.76kN. The maximum shock input acceleration was 20 g, and impulse width was lores. Both the vibration and shock loads were applied using MTS Systems Corporation's hydraulic actuators. The experimental results indicated that the isolator system performs well on system vibration response, with resonance humps of the vibration response obviously reduced after using the MR damper. For the shock experiment, the attenuation of shock response was much faster with increased MR damping. The MR damper's effect on shock moments was very different from its performance in vibration mode. The correlation between MR force and control current was not as evident as it was during vibration loads.展开更多
In this paper;the dynamic characteristics of a semi-active magnetorheological fluid(MRF)engine mount are studied.To do so,the performance of the MRF engine mount is experimentally examined in higher frequencies(50~170...In this paper;the dynamic characteristics of a semi-active magnetorheological fluid(MRF)engine mount are studied.To do so,the performance of the MRF engine mount is experimentally examined in higher frequencies(50~170 Hz)and the various amplitudes(0.01~0.2 mm).In such an examination,an MRF engine mount along with its magnetically biased is fabricated and successfully measured.In addition,the natural frequencies of the system are obtained by standard hammer modal test.For modelling the behavior of the system,a mass-spring-damper model with tuned PID coefficients based on Pessen integral of absolute error method is used.The parameters of such a model including mass,damping ratio,and stiffness are identified with the help of experimental modal tests and the recursive least square method(RLS).It is shown that using PID controller leads to reducing the vibration transmissibility in the resonance frequency(=93.45 Hz)with respect to the typical passive engine mount by a factor of 58%.The average of the vibration transmissibility decreasing is also 43%within frequency bandwidth(50~170 Hz).展开更多
A combined magnetorheological damper combined with rubber spring and magnetorheological damper is addressed.This type of damping device has inherited the merits of rubber spring and the magnetorheological damper.The t...A combined magnetorheological damper combined with rubber spring and magnetorheological damper is addressed.This type of damping device has inherited the merits of rubber spring and the magnetorheological damper.The test damping device is made up of combined magnetorheological damper,amplitude controller,signal collecting device,computer software for dynamic analysis,etc.When a zeromean and non-Gaussian white noise interfere with the device,a time series autoregressive(AR) model is conducted by using the sampled experimental data.Trispectrum and its slices analysis are emerging as a new powerful technique in signal processing,which is put forward for investigating the dynamic characteristics of the magnetorheological vibrant device.The present of trispectrum and its slices analysis change with the variation of controllable working magnetic field of the damper correspondingly.It is indicated that AR trispectrum and its slices analysis methods are feasible and effective for investigation of magnetorheological vibrant device.展开更多
文摘Using magnetorheological (MR) fluids in hydraulic engine mount for damping vehicle noise and vibration is opposed firstly, the structure of passive type and its mechanical model are described. The analysis of the experimental data show that the dynamic characteristics of MR mount such as dynamic stiffness and loss angles vary distinctly as the excitation frequency, and MR fluids as one type of attracting controllable fluids are fit for hydraulic engine mounts. The author advises to work out potentialities of MR fluids, the semi control or active control MR fluids filled hydraulic engine mount must be developed.
基金Supported by Basic Science Research Program of National Research Foundation of Korea,Ministry of Education,Science and Technology of the Korean(Grant No.NRF-2015R1D1A1A09060901)Ministry of Science,ICT and Future Planning,Korea,under Convergence Information Technology Research Center(Grant No.IITP-2015-H8601-15-1003) supervised by Institute for Information&Communications Technology PromotionAdvanced Technology Center R&D Program funded by the Ministry of Trade,Industry&Energy of Korea(Grant No.10048876)
文摘Magnetorheological (MR) fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic field, which is known as MR effect, resulting in variation of stiffness, shear modulus, damping and tribological characteristics of MR fluid. As MR effect depends on the density of particles in the fluid or the strength of a magnetic field, the experiments are conducted to evaluate the friction property under reciprocating motion by changing the types of MR fluid and the strength of a magnetic field. The material of aluminum, brass, and steel are chosen for specimen as they are the most common material in mechanical applications. The surfaces of specimen are also observed by optical microscope before and after experiments to compare the surfaces with test conditions. The comparing results show that the friction coefficient increases as the strength of a magnetic field increases in regardless of types of MR fluid or the material. Also the density of particle in MR fluid affects the friction characteristic. The results from this research can be used to improve the performance of mechanical applications using MR fluid.
基金Supported by the National Program on Key Basic Research Program(″973″Program)(2012CB026000)the Ph.D.Programs Foundation of Ministry of Education of China(20110010110009)
文摘The aim of this work is to analyze and design a control system for vibration reduction in a rotor system using a shear mode magnetorheological fluid(MRF)damper.A dynamic model of the MRF damper-rotor system was built and simulated in Matlab/Simulink to analyze the rotor vibration characteristics and the vibration reduction effect of the MRF damper.Based on the numerical simulation analysis,an optimizing control strategy using pattern search method was proposed and designed.The control system was constructed on a test rotor bench and experiment validations on the effectiveness of the proposed control strategy were conducted.Experimental results show that rotor vibration caused by unbalance can be well controlled whether in resonance region(70%)or in non-resonance region(30%).An irregular vibration amplitude jump can be suppressed with the optimization strategy.Furthermore,it is found that the rapidity of transient response and efficiency of optimizing technique depend on the pattern search step.The presented strategies and control system can be extended to multi-span(more than two or three spans)rotor system.It provides a powerful technical support for the extension and application in target and control for shafting vibration.
基金Funded by National Natural Science Foundation of China(No.51475454)National Natural Science Foundation of JiangsuProvince(No.BK20151144)+1 种基金Fundamental Research Funds forthe Central Universities(No.2014QNA38)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘In order to study the squeeze-strengthening effect of silicone oil-based magnetorheological fluid (MRF), theoretical basis of disc squeezing brake was presented and a squeezing braking characteristics test-bed for MRF was designed. Moreover, relevant experiments were carded out and the relationship between squeezing pressure and braking torque was proposed. Experiments results showed that the yield stress of MRF improved linearly with the increasing of external squeezing pressure and the braking torque increased three times when external squeezing pressure achieved 2 MPa.
基金National Natural Science Foundation of China(No.60674097,No.60574074)National Hi-tech Research and Development Program of China(863 Program,No.2006AA03ZI04)Postdoctoral Science Foundation of China(No.20070410204).
文摘The Bingham constitutive model, which is previously used in depiction of magnetorheological (MR) fluids rheological behaviors for design devices, exhibits discontinuous characteristics in representation of pre-yield behaviors and post-yield behaviors. A Biviscous constitutive model is presented to depict rheological behaviors of MR fluids and design automotive shock absorber. Quasi-static flow equations of MR fluids in annular channels are set theoretically up based on Navier-Stokes equations and several rational simplifications are made. And both flow boundary conditions and flow compatibilities conditions are established. Meantime, analytical velocity profiles of MR fluids though annular channels are obtained via solution of the quasi-static flow equations using Biviscous constitutive model. The prediction methodology of damping force offered by MR fluid shock absorber is formulated and damping performances are predicated in order to determine design parameters. MR fluid shock absorber for Mazda 323 car suspension is designed and fabricated in Chongqing University, China. Measurements from sinusoidal displacement cycle by Shanchuan Shock Absorber Ltd. of China North Industry Corporation reveal that the analytical methodology and design theory are reasonable.
基金Project (2010-0015090) supported by the National Research Foundation of Korea
文摘A pin-on-disc wear apparatus was used to carry out the tribological experiment of brass to investigate the effect of a magnetorheological (MR) fluid on the interfacial surface with and without magnetic field. A series of tests were performed at the loads of 20-100 N and rotating speeds of 127-425 r/min for 2 h. The friction coefficient and wear rate were monitored by the wear apparatus, while the microstructures of the worn surfaces were observed by scanning electron microscope (SEM). In addition, the chemical composition of worn surfaces was analyzed by energy dispersive X-ray spectroscopy (EDS). Test results show different friction and wear performance of the MR fluid with and without magnetic field. At the same time, the effects of various normal loads and rotating speeds on the tribological behavior were investigated. Through the investigation of the morphologies of the wom surfaces under the magnetic field, it is found that the MR particles are clearly evident on the wom surface and the plastic flow of ridges causes the lateral extrusion. This directly indicates that abrasive wear is the predominant wear mechanism observed with MR fluid.
基金Supported by the National Program on Key Basic Research Project(973Program)(2012CB026000)Ph.D Programs Foundation of Ministry of Education of China(20110010110009)
文摘A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological (MRF) dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled ( first critical speed region 37% , second critical speed region 42% ). To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.
文摘In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45# transformer oil,was finished.And characteristics of these samples were tested and analyzed.The results show that Tween-80 and Span-80 can improve the sedimentary stability,and the larger mass fraction can also increase the sedimentary stability.Using 45# transformer oil instead of special shock absorption fluid as a carrier of MRF,the shear yield stress remains nearly constant but the viscosity and the sedimentary stability are reduced.The MRF with diameter of 2.73 μm shows better sedimentary stability than that of the MRF with diameter of 2.30 μm,or 4.02 μm.Stearic acid obviously improves sedimentary stability and off-state viscosity,but has no function on the shear yield stress.In magnetic field of 237 kA/m,the shear yield stress of MRF based on special shock absorption fluid is 18.34 kPa and the shear yield stress of MRF based on 45# transformer oil is 14.26 kPa.
基金Funded by the"863"Hi tech Research and Development Program of China(No.2001AA33P020)
文摘Based on the single-chain structure model of magnetorheological fluids, a formu la for the calculation of shear stresses was established. The interaction force of two magnetic particles in an infinite single-chain was deduced using a new theoretical model which is founded on Ampere' molecular curr ent hypothesis, dipole theory and Ampere' law. Furthermore, the resultant force on a particle was then deduced by taking into account of the action caused by al l the other particles in the single-chain. A predictive formula for shear stres ses was made corresponding to the case that MR fluids were sheared by a small an gle and the calculating results fit well on the order with the yield stresses of the commercial MR fluids.
基金Supported by the National Natural Science Foundation of China(No.51375423,51505410)the National Key Basic Research Program(No.2014CB046400)
文摘With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various parameters on damping force characteristics. A mathematical model of the output damping force on the MRF damper is established by the mechanism modeling method,a first order output sensitivity equation is deduced and the expression of the first order output sensitivity function is obtained. The first-order sensitivity functions of ten design parameters are solved,and the influence degree of system parameters change on the output force of MRF damper is analyzed by comparing the sensitivity index of the parameters. Two sensitivities of vibration velocity and control current are obtained through experiment to prove the other parameters sensitivity analysis conclusion by analogy verification,which provides guidance for the structure optimization design of MRF damper.
基金supported by the Key Research Development and Promotion Special Project of Henan Province,under Grant 212102310119 and 212102210358Scientific Research Foundation for High-level Talents of Henan Institute of Technology,under Grant KQ1869+6 种基金Research and Practice Project of Higher Education Teaching Reform in Henan Province,under Grant 2021SJGLX289University-Industry Collaborative Education Program,under Grant 202101187010 and 202102120046Innovation and Entrepreneurship Training Program for College Students of Henan Province,under Grant 202211329011Educational and Teaching Reform Research and Practice Project of Henan Institute of Technology,under Grant 2021-YB023 and JJXY-2021005Innovative Education Curriculum Construction Project of Henan Institute of Technology,under Grant CX-2021-0052022 Xinxiang Federation of Social Sciences Research topic,under Grant SKL-2022-254 and SKL-2022-2282022 Annual Research Topic of Henan Federation of Social Sciences,under Grant SKL-2022-2692.
文摘To address the problem of flexible drive control of gastrointestinal(GI)tract micro-capsule robot posture,a novel dual helix magnetorheological fluid(MRF)micro-robot(DHMRFMR)is proposed and developed in this paper.Based on the mechanical properties of magnetorheological fluid,the relationship model of magnetic field force is obtained,and the thrust model is established.Double micro DC deceleration motor is used to drive the two ends of the helical actuator to make the DHMRFMR forward and backward,by changing the external magnetic field rotation speed,direction and distance,adjust the attitude direction of the robot.Numerical simulation software ANSYS is used to analyze the motion law of external fluid of DHMRFMR,and the visualization of fluid velocity and pressure distribution is realized.The front-end helix actuator can change the flow path of the fluid,and the middle and tail of the DHMRFMR bear less pressure,which improves the stability and flexibility of the robot.The novel DHMRFMR is suitable for internal drive in bending environment,and has a good application prospect in biomedical engineering field in human intestinal unstructured environment.
文摘Isolator systems on ships should ideally be able to simultaneously reduce low frequency vibration response and high frequency shock response. Conventional isolator systems are unable to do so To solve the problem, a new style isolator system was created. This isolator system consists of a steel coil spring component and a magnetorheological (MR) damper component working in parallel. Experiments on this isolator system were carried out, including tests of vibration reduction and shock resistance. The vibration load frequencies were set from 1-15 Hz, and force amplitudes from 2.94-11.76kN. The maximum shock input acceleration was 20 g, and impulse width was lores. Both the vibration and shock loads were applied using MTS Systems Corporation's hydraulic actuators. The experimental results indicated that the isolator system performs well on system vibration response, with resonance humps of the vibration response obviously reduced after using the MR damper. For the shock experiment, the attenuation of shock response was much faster with increased MR damping. The MR damper's effect on shock moments was very different from its performance in vibration mode. The correlation between MR force and control current was not as evident as it was during vibration loads.
文摘In this paper;the dynamic characteristics of a semi-active magnetorheological fluid(MRF)engine mount are studied.To do so,the performance of the MRF engine mount is experimentally examined in higher frequencies(50~170 Hz)and the various amplitudes(0.01~0.2 mm).In such an examination,an MRF engine mount along with its magnetically biased is fabricated and successfully measured.In addition,the natural frequencies of the system are obtained by standard hammer modal test.For modelling the behavior of the system,a mass-spring-damper model with tuned PID coefficients based on Pessen integral of absolute error method is used.The parameters of such a model including mass,damping ratio,and stiffness are identified with the help of experimental modal tests and the recursive least square method(RLS).It is shown that using PID controller leads to reducing the vibration transmissibility in the resonance frequency(=93.45 Hz)with respect to the typical passive engine mount by a factor of 58%.The average of the vibration transmissibility decreasing is also 43%within frequency bandwidth(50~170 Hz).
基金Project(2005H035) supported by Fujian Province of China
文摘A combined magnetorheological damper combined with rubber spring and magnetorheological damper is addressed.This type of damping device has inherited the merits of rubber spring and the magnetorheological damper.The test damping device is made up of combined magnetorheological damper,amplitude controller,signal collecting device,computer software for dynamic analysis,etc.When a zeromean and non-Gaussian white noise interfere with the device,a time series autoregressive(AR) model is conducted by using the sampled experimental data.Trispectrum and its slices analysis are emerging as a new powerful technique in signal processing,which is put forward for investigating the dynamic characteristics of the magnetorheological vibrant device.The present of trispectrum and its slices analysis change with the variation of controllable working magnetic field of the damper correspondingly.It is indicated that AR trispectrum and its slices analysis methods are feasible and effective for investigation of magnetorheological vibrant device.