A new type of isolator, the electrorheology (ER) isolator, is mainly described. Through theoretical analysis, a simplified physical model is established under some hypotheses and a series of motion equations are deduc...A new type of isolator, the electrorheology (ER) isolator, is mainly described. Through theoretical analysis, a simplified physical model is established under some hypotheses and a series of motion equations are deduced. According to the transmissibility curve simulation under different electric field strengths, the main factors influencing ER isolator’s working properties have been ascertained. Finally, it proves that ER isolator works well in both low and high frequency zones, it can decrease the force transmitted and enlarge the isolation frequency domain efficiently.展开更多
Presented in this paper is a semi active vibration control strategy based on the vibration absorber with adjustable clearance in elastic component. The control law of the clearance for alleviating the vibration of pr...Presented in this paper is a semi active vibration control strategy based on the vibration absorber with adjustable clearance in elastic component. The control law of the clearance for alleviating the vibration of primary system is derived by means of harmonic balancing technique so that the working frequency of the vibration absorber can trace the frequency variation of the harmonic excitation. The efficacy of the strategy is demonstrated by numerical simulations for attenuating the steady state vibration of a SDOF system and a 2 DOF system, which are under the harmonic excitation with slowly varied frequency in a wide range.展开更多
In wind tunnel tests,long cantilever stings are usually used to support aerodynamic models.However,this kind of sting support system is prone to vibration problems due to its low damping,which limits the test envelope...In wind tunnel tests,long cantilever stings are usually used to support aerodynamic models.However,this kind of sting support system is prone to vibration problems due to its low damping,which limits the test envelope and affects the data quality.It is shown in many studies that the sting vibration can be effectively reduced by using active sting dampers based on piezoelectric actuators.This paper attempts to review the research progress of piezoelectric vibration control in wind tunnel tests,covering the design of active sting dampers,control methods and wind tunnel applications.First of all,different design schemes of active sting dampers are briefly introduced,along with the vibration damping principle.Then,a comprehensive review of the control methods for active sting dampers is presented,ranging from classic control methods,like PID control algorithm,to various intelligent control methods.Furthermore,the applications of active sting dampers and controllers in different wind tunnels are summarized to evaluate their vibration damping effect.Finally,the remaining problems that need to be solved in the future development of piezoelectric vibration control in wind tunnel tests are discussed.展开更多
A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper,which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic ch...A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper,which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties by the application of an external magnetic field. The magneticfield of the disc-type MR fluid damper is analysed by the finite element method ; the controllability of the disctype MR fluid damper on the dynamic behaviour of a rotor system ; and the effectiveness of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with an over-hung disc. It is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly change with the applied current in the coil ; and that the dynamic behavior of the disc-type MR fluid damper can be varied by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating machinery.展开更多
An active temperature compensated fiber Bragg grating(FBG)vibration sensor with a constant section cantilever beam is proposed for the simultaneous measurement of temperature and vibration,and the sensor is verified b...An active temperature compensated fiber Bragg grating(FBG)vibration sensor with a constant section cantilever beam is proposed for the simultaneous measurement of temperature and vibration,and the sensor is verified by a temperature compensation feedback system.The high-temperature vibration sensor is composed of a quartz cantilever beam and a femtosecond Bragg grating.The feedback control demodulation system of active temperature compensation can adjust the laser wavelength to stabilize the grating offset point and realize simultaneous measurement of temperature and vibration.On this basis,the performance of the sensor is tested and analyzed within the range of 20-400℃by setting up a high-temperature vibration test system.The experimental results show that the sensitivity of the sensor is about 132.33 mV/g,and the nonlinearity is about 3.33%.The sensitivity between the laser wavelength and temperature is about 0.01307 nm/℃.In addition,the active temperature compensated fiber Bragg grating vibration sensor has the advantages of a simple structure,stable performance,easy demodulation and high sensitivity.Moreover,the sensor can achieve high temperature vibration signal monitoring and has good practical application value.展开更多
The vibrating string pressure sensor is designed according to the working surroundings and conditions. this sensor is used for the weighing of the fixed-quantity bucket loader in the main shaft lifting systems of coal...The vibrating string pressure sensor is designed according to the working surroundings and conditions. this sensor is used for the weighing of the fixed-quantity bucket loader in the main shaft lifting systems of coal mines. The design of the sensor has been introduced in detail. Calibrations and errors of the sensor theoretical fornada have also been analyzed.展开更多
In this paper, the method of semi-active control with variable damper is presented to deal with the relatively poor transversal seismic condition of bridge. Based on the LQR control algorithm the control effectiveness...In this paper, the method of semi-active control with variable damper is presented to deal with the relatively poor transversal seismic condition of bridge. Based on the LQR control algorithm the control effectiveness for transverse vibration of pier-beam structure of bridge are discussed. Taking the structure as a multiple-degree of freedom system, the calculating model of structure-variable damper system is set up and the differential equation is derived, combined with practical example the control system is simulated and studied by various semi-active control algorithms and passive strategy with MATLAB. The results show that the semi-active control with variable damper can decrease the transverse vibration effectively and the control effect is obvious.展开更多
As described in this paper, we propose a new haptic interface for a service robot. For safety with service robots working in a space where people live, some notification before collision with an obstacle is desirable....As described in this paper, we propose a new haptic interface for a service robot. For safety with service robots working in a space where people live, some notification before collision with an obstacle is desirable. To achieve such a function, we developed a master-slave manipulator system in which the slave manipulator surface is covered with many proximity sensors. Additionally, we developed a haptic device that feeds back proximity sense information to the operator using small vibration motors. We attached the haptic device to the arm of the operator and vibrated the vibration motor corresponding to the sensor. Thereby, the operator was able to ascertain the position of an object near the manipulator, and to make the robot maneuver to avoid it before collision. To confirm the system usefulness, we equipped subjects with the developed proximity sense presentation device and performed a detection-position-specific experiment and an obstacle avoidance experiment in a narrow space. As results of the detection position specific experiment on five subjects, four subjects reported the detection position correctly. The remaining one person failed because of his particular arm shape. Operation experiments conducted in a narrow space showed that all subjects＇ work was successful when given feedback of proximity sense information. Nobody was successful without proximity sense information. Results of these two experiments demonstrate that this proposed system is useful for obstacle avoidance of a master-slave manipulator system.展开更多
Tail buffeting at high angle of attack causes distinct fatigue problem on tail structure of twin tail fighters.In this study,a piezoelectric active control experiment of tail buffeting was performed in a wind tunnel u...Tail buffeting at high angle of attack causes distinct fatigue problem on tail structure of twin tail fighters.In this study,a piezoelectric active control experiment of tail buffeting was performed in a wind tunnel using arching PZT actuator(APA) and principal modal control(PMC) method.Test results showed the peak value of power spectral density(PSD) function of tail buffeting acceleration response could be suppressed by about 42% when the angle of attack reached 35°,indicating the validity and feasibility of PMC method and APA for tail buffeting alleviation at high angle of attack.展开更多
文摘A new type of isolator, the electrorheology (ER) isolator, is mainly described. Through theoretical analysis, a simplified physical model is established under some hypotheses and a series of motion equations are deduced. According to the transmissibility curve simulation under different electric field strengths, the main factors influencing ER isolator’s working properties have been ascertained. Finally, it proves that ER isolator works well in both low and high frequency zones, it can decrease the force transmitted and enlarge the isolation frequency domain efficiently.
文摘Presented in this paper is a semi active vibration control strategy based on the vibration absorber with adjustable clearance in elastic component. The control law of the clearance for alleviating the vibration of primary system is derived by means of harmonic balancing technique so that the working frequency of the vibration absorber can trace the frequency variation of the harmonic excitation. The efficacy of the strategy is demonstrated by numerical simulations for attenuating the steady state vibration of a SDOF system and a 2 DOF system, which are under the harmonic excitation with slowly varied frequency in a wide range.
基金supported by the Foundation of National Key Laboratory on Ship Vibration and Noise(No. 614220400307)the National Natural Science Foundation of China(No.11872207)+1 种基金the Aeronautical Science Foundation of China(No. 20180952007)the Foundation of State Key Laboratory of Mechanics and Control of Mechanical Structures(No. MCMS-I-0520G01)
文摘In wind tunnel tests,long cantilever stings are usually used to support aerodynamic models.However,this kind of sting support system is prone to vibration problems due to its low damping,which limits the test envelope and affects the data quality.It is shown in many studies that the sting vibration can be effectively reduced by using active sting dampers based on piezoelectric actuators.This paper attempts to review the research progress of piezoelectric vibration control in wind tunnel tests,covering the design of active sting dampers,control methods and wind tunnel applications.First of all,different design schemes of active sting dampers are briefly introduced,along with the vibration damping principle.Then,a comprehensive review of the control methods for active sting dampers is presented,ranging from classic control methods,like PID control algorithm,to various intelligent control methods.Furthermore,the applications of active sting dampers and controllers in different wind tunnels are summarized to evaluate their vibration damping effect.Finally,the remaining problems that need to be solved in the future development of piezoelectric vibration control in wind tunnel tests are discussed.
文摘A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper,which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties by the application of an external magnetic field. The magneticfield of the disc-type MR fluid damper is analysed by the finite element method ; the controllability of the disctype MR fluid damper on the dynamic behaviour of a rotor system ; and the effectiveness of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with an over-hung disc. It is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly change with the applied current in the coil ; and that the dynamic behavior of the disc-type MR fluid damper can be varied by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating machinery.
基金National Natural Science Foundation of China(No.51935011)Natural Science Foundation of Shanxi Province of China(No.201901D111160)Innovative Research Group Project of National Science Foundation of China(No.51821003)。
文摘An active temperature compensated fiber Bragg grating(FBG)vibration sensor with a constant section cantilever beam is proposed for the simultaneous measurement of temperature and vibration,and the sensor is verified by a temperature compensation feedback system.The high-temperature vibration sensor is composed of a quartz cantilever beam and a femtosecond Bragg grating.The feedback control demodulation system of active temperature compensation can adjust the laser wavelength to stabilize the grating offset point and realize simultaneous measurement of temperature and vibration.On this basis,the performance of the sensor is tested and analyzed within the range of 20-400℃by setting up a high-temperature vibration test system.The experimental results show that the sensitivity of the sensor is about 132.33 mV/g,and the nonlinearity is about 3.33%.The sensitivity between the laser wavelength and temperature is about 0.01307 nm/℃.In addition,the active temperature compensated fiber Bragg grating vibration sensor has the advantages of a simple structure,stable performance,easy demodulation and high sensitivity.Moreover,the sensor can achieve high temperature vibration signal monitoring and has good practical application value.
文摘The vibrating string pressure sensor is designed according to the working surroundings and conditions. this sensor is used for the weighing of the fixed-quantity bucket loader in the main shaft lifting systems of coal mines. The design of the sensor has been introduced in detail. Calibrations and errors of the sensor theoretical fornada have also been analyzed.
文摘In this paper, the method of semi-active control with variable damper is presented to deal with the relatively poor transversal seismic condition of bridge. Based on the LQR control algorithm the control effectiveness for transverse vibration of pier-beam structure of bridge are discussed. Taking the structure as a multiple-degree of freedom system, the calculating model of structure-variable damper system is set up and the differential equation is derived, combined with practical example the control system is simulated and studied by various semi-active control algorithms and passive strategy with MATLAB. The results show that the semi-active control with variable damper can decrease the transverse vibration effectively and the control effect is obvious.
文摘As described in this paper, we propose a new haptic interface for a service robot. For safety with service robots working in a space where people live, some notification before collision with an obstacle is desirable. To achieve such a function, we developed a master-slave manipulator system in which the slave manipulator surface is covered with many proximity sensors. Additionally, we developed a haptic device that feeds back proximity sense information to the operator using small vibration motors. We attached the haptic device to the arm of the operator and vibrated the vibration motor corresponding to the sensor. Thereby, the operator was able to ascertain the position of an object near the manipulator, and to make the robot maneuver to avoid it before collision. To confirm the system usefulness, we equipped subjects with the developed proximity sense presentation device and performed a detection-position-specific experiment and an obstacle avoidance experiment in a narrow space. As results of the detection position specific experiment on five subjects, four subjects reported the detection position correctly. The remaining one person failed because of his particular arm shape. Operation experiments conducted in a narrow space showed that all subjects＇ work was successful when given feedback of proximity sense information. Nobody was successful without proximity sense information. Results of these two experiments demonstrate that this proposed system is useful for obstacle avoidance of a master-slave manipulator system.
基金supported by the National Natural Science Foundation of China (Grant No. 11072198)the Basic Research Program of Northwestern Polytechnical University (Grant No. JC201102) "111" Project(Grant No. B07050)
文摘Tail buffeting at high angle of attack causes distinct fatigue problem on tail structure of twin tail fighters.In this study,a piezoelectric active control experiment of tail buffeting was performed in a wind tunnel using arching PZT actuator(APA) and principal modal control(PMC) method.Test results showed the peak value of power spectral density(PSD) function of tail buffeting acceleration response could be suppressed by about 42% when the angle of attack reached 35°,indicating the validity and feasibility of PMC method and APA for tail buffeting alleviation at high angle of attack.
