An air damper possesses the advantages that there are no long term changes in the damping properties, there is no dependence on working temperature and additionally, it has less manufacturing and maintenance costs. As...An air damper possesses the advantages that there are no long term changes in the damping properties, there is no dependence on working temperature and additionally, it has less manufacturing and maintenance costs. As such, an air damper has been designed and developed based on the Maxwell type model concept in the approach of Nishihara and Asami [1]. The cylinder-piston and air-tank type damper characteristics such as air damping ratio and air spring rate have been studied by changing the length and diameter of the capillary pipe between the air cylinder and the air tank, operating air pressure and the air tank volume. A SDOF quarter-car vehicle suspension system using the developed air enclosed cylinder-piston and air-tank type damper has been analyzed for its motion transmissibility characteristics. Optimal values of the air damping ratio at various values of air spring rate have been determined for minimum motion transmissibility of the sprung mass. An experimental setup has been developed for SDOF quarter-car suspension system model using the developed air enclosed cylinder-piston and air-tank type damper to determine the motion transmissibility characteristics of the sprung mass. An attendant air pressure control system has been designed to vary air damping in the developed air damper. The results of the theoretical analysis have been compared with the experimental analysis.展开更多
In this paper, it is shown that, a road vehicle 2DOF air damped quartercar suspension system can conveniently be transformed into a 2DOF air damped vibrating system representing an air damped dynamic vibration absorbe...In this paper, it is shown that, a road vehicle 2DOF air damped quartercar suspension system can conveniently be transformed into a 2DOF air damped vibrating system representing an air damped dynamic vibration absorber (DVA) with an appropriate change in the ratio μ of the main mass and the absorber mass i.e. when mass ratio μ >> 1. Also the effect of variation of the mass ratio, air damping ratio and air spring rate ratio, on the motion transmissibility at the resonant frequency of the main mass of the DVA has been dis- cussed. It is shown that, as the air damping ratio in the absorber system increases, there is a substantial decrease in the motion transmissibility of the main mass system where the air damper has been modeled as a Maxwell type. Optimal value of the air damping ratio for the minimum motion transmissibility of the main mass of the system has been determined. An experimental setup has been designed and developed with a control system to vary air pressure in the damper in the absorber system. The motion transmissibility characteristics of the main mass system have been obtained, and the optimal value of the air damping ratio has been determined for minimum motion transmissibility of the main mass of the展开更多
Passively stabilized double-wing Flapping Micro Air Vehicles(FMAVs)do not require active control and exhibit good electromagnetic interference resistance,with significant research value.In this paper,the dynamic model...Passively stabilized double-wing Flapping Micro Air Vehicles(FMAVs)do not require active control and exhibit good electromagnetic interference resistance,with significant research value.In this paper,the dynamic model of FMAV was established as the foundation for identifying flapping damping coefficients.Through a pendulum experiment,we ascertain the flapping damping of the damper using the energy conservation method.Besides,fitting relationships between the damper area,damper mass,and the moment of inertia are developed.The factors influencing the bottom damper damping are deter-mined using correlation coefficients and hypothesis testing methods.Additionally,stable dampers are installed on both the top and bottom of the FMAV to achieve passive stability in simulations.The minimum damper areas for the FMAV were optimized using genetic algorithms,resulting in a minimum top damper area of 128 cm^(2) and a minimum bottom damper area of 80 cm^(2).A prototype with a mass of 25.5 g and a wingspan of 22 cm has been constructed.Prototype testing demonstrated that FMAV can take off stably with a 3 g payload and a tilt angle of 5°.During testing,the area-to-mass ratio of the FMAV reached 7.29 cm^(2)/g,achieving passive stability with the world's smallest area-to-mass ratio.展开更多
The ionic-wind-powered Micro Air Vehicles(MAVs)can achieve a higher thrust-toweight ratio than other MAVs.However,this kind of MAV has not yet achieved controlled flight because of the unstable thrust produced by the ...The ionic-wind-powered Micro Air Vehicles(MAVs)can achieve a higher thrust-toweight ratio than other MAVs.However,this kind of MAV has not yet achieved controlled flight because of the unstable thrust produced by the ionic wind and the dynamic instability related to the small size.In this paper,a passive attitude stabilization method of the ionic-wind-powered MAV using air dampers is introduced.The key factors that influence the performance of the air dampers,including the layout,position,and area of the air dampers,are theoretically studied.The appropriate optimal position of the air dampers is also obtained by Monte Carlo stochastic simulations.Then the proposed passive attitude stabilization method is applied to the ionic-wind-powered MAVs of different wingspan(2 cm and 6.3 cm).Finally,the experimental results show that using the proposed method,attitude stabilization is achieved for the first time for the ionic-wind-powered MAV.Moreover,the altitude control of an ionic-wind-powered MAV with a wingspan of 6.3 cm is also demonstrated.展开更多
文摘An air damper possesses the advantages that there are no long term changes in the damping properties, there is no dependence on working temperature and additionally, it has less manufacturing and maintenance costs. As such, an air damper has been designed and developed based on the Maxwell type model concept in the approach of Nishihara and Asami [1]. The cylinder-piston and air-tank type damper characteristics such as air damping ratio and air spring rate have been studied by changing the length and diameter of the capillary pipe between the air cylinder and the air tank, operating air pressure and the air tank volume. A SDOF quarter-car vehicle suspension system using the developed air enclosed cylinder-piston and air-tank type damper has been analyzed for its motion transmissibility characteristics. Optimal values of the air damping ratio at various values of air spring rate have been determined for minimum motion transmissibility of the sprung mass. An experimental setup has been developed for SDOF quarter-car suspension system model using the developed air enclosed cylinder-piston and air-tank type damper to determine the motion transmissibility characteristics of the sprung mass. An attendant air pressure control system has been designed to vary air damping in the developed air damper. The results of the theoretical analysis have been compared with the experimental analysis.
文摘In this paper, it is shown that, a road vehicle 2DOF air damped quartercar suspension system can conveniently be transformed into a 2DOF air damped vibrating system representing an air damped dynamic vibration absorber (DVA) with an appropriate change in the ratio μ of the main mass and the absorber mass i.e. when mass ratio μ >> 1. Also the effect of variation of the mass ratio, air damping ratio and air spring rate ratio, on the motion transmissibility at the resonant frequency of the main mass of the DVA has been dis- cussed. It is shown that, as the air damping ratio in the absorber system increases, there is a substantial decrease in the motion transmissibility of the main mass system where the air damper has been modeled as a Maxwell type. Optimal value of the air damping ratio for the minimum motion transmissibility of the main mass of the system has been determined. An experimental setup has been designed and developed with a control system to vary air pressure in the damper in the absorber system. The motion transmissibility characteristics of the main mass system have been obtained, and the optimal value of the air damping ratio has been determined for minimum motion transmissibility of the main mass of the
基金support by the Natural Science Foundation of China under Grant 61871266the Professional technical service platform of Shanghai under Grant 19DZ2291103.
文摘Passively stabilized double-wing Flapping Micro Air Vehicles(FMAVs)do not require active control and exhibit good electromagnetic interference resistance,with significant research value.In this paper,the dynamic model of FMAV was established as the foundation for identifying flapping damping coefficients.Through a pendulum experiment,we ascertain the flapping damping of the damper using the energy conservation method.Besides,fitting relationships between the damper area,damper mass,and the moment of inertia are developed.The factors influencing the bottom damper damping are deter-mined using correlation coefficients and hypothesis testing methods.Additionally,stable dampers are installed on both the top and bottom of the FMAV to achieve passive stability in simulations.The minimum damper areas for the FMAV were optimized using genetic algorithms,resulting in a minimum top damper area of 128 cm^(2) and a minimum bottom damper area of 80 cm^(2).A prototype with a mass of 25.5 g and a wingspan of 22 cm has been constructed.Prototype testing demonstrated that FMAV can take off stably with a 3 g payload and a tilt angle of 5°.During testing,the area-to-mass ratio of the FMAV reached 7.29 cm^(2)/g,achieving passive stability with the world's smallest area-to-mass ratio.
基金supported by the National Natural Science Foundation of China (No.12002017)the 111 Project, China (No. B08009)
文摘The ionic-wind-powered Micro Air Vehicles(MAVs)can achieve a higher thrust-toweight ratio than other MAVs.However,this kind of MAV has not yet achieved controlled flight because of the unstable thrust produced by the ionic wind and the dynamic instability related to the small size.In this paper,a passive attitude stabilization method of the ionic-wind-powered MAV using air dampers is introduced.The key factors that influence the performance of the air dampers,including the layout,position,and area of the air dampers,are theoretically studied.The appropriate optimal position of the air dampers is also obtained by Monte Carlo stochastic simulations.Then the proposed passive attitude stabilization method is applied to the ionic-wind-powered MAVs of different wingspan(2 cm and 6.3 cm).Finally,the experimental results show that using the proposed method,attitude stabilization is achieved for the first time for the ionic-wind-powered MAV.Moreover,the altitude control of an ionic-wind-powered MAV with a wingspan of 6.3 cm is also demonstrated.
