| The vibration is an inevitable disturbance in the working process of moving carriers,including: vehicles,ships,helicopters,etc.It will lead to wear and tear of parts,failure of instruments and equipment,and even cause major accidents.Practice has proved that the vibration is often a random disturbance.The traditional passive vibration reduction system does not have the function of adaptive damping,and it is difficult to ensure that the moving carrier maintains good working performance at all times.Therefore,in this paper,the magnetorheological(MR)fluid vibration reduction technology was used as a means to design a reasonable vibration reduction mechanism for the helicopter main reducer system,the armoured vehicle seat suspension system and the wheeled armoured vehicle suspension system.The appropriate semi-active control strategy was proposed to realize the adaptive vibration reduction of the MR vibration reduction system and improve the working performance of the moving carrier.The main research contents of this paper are as follows.(1)According to the performance requirements of different vibration reduction systems,the multi-objective optimization design of MR damper structure was completed by the nondominated sorting genetic algorithm version II(NSGA-II)with the optimization objectives of the maximum dynamic range and the minimum number of turns of electromagnetic coil.The single-rod valve mode MR damper with the advantages of light weight,good electromagnetic compatibility and high integration was developed for light helicopter main reducer vibration reduction system.A double rod shear-valve mode MR damper with small stroke and large output force was developed for heavy helicopter main reducer vibration reduction system.A double rod shear-valve mode MR damper with large stroke and multi-stage coil was developed for armoured vehicle seat suspension system.The mechanical properties test results shown that the three MR dampers have large dynamic range and good working performance,which meet the design requirements.(2)Parameters of the Bouc-Wen model were identified using the artificial fish swarm algorithm.And the electromagnetic coupling model which can accurately describe the mechanical behavior of the double rod MR damper was established.To overcome the shortcomings of the Bouc-Wen model in the modeling process of the double rod MR damper,such as too many parameters,complex identification process,and long time consuming,a Bouc–Wen optimum model with high identification efficiency and high simulation accuracy was established.Based on the results of the single-rod damper’s mechanical property test,the parameter identification of the Bouc–Wen optimum model is completed.Comparing with the original Bouc-Wen model,the Bouc–Wen optimum model can accurately and efficiently simulate the dynamic characteristics of the MR damper.(3)According to the protection requirements of armored vehicle seat,a new MR seat for both shock and vibration mitigation was designed and developed.Based on the semi-active characteristics of MR damper and the working characteristics of seat suspension,a hybrid semiactive control strategy considering vibration reduction control and shock control was proposed.The simulation and test results shown that the MR seat with semi-active control can effectively improve the ride comfort and safety of drivers and passengers.(4)A MR vibration reduction platform(VRP)with cubic structure Stewart mechanism was proposed for the helicopter to effectively reduce the vibration of the helicopter rotor transmitted from the main reducer to the fuselage.According to the vibration reduction requirements of the main reducer of light and heavy helicopter,the structural design of the light load type and heavy load type MR 6-DOF VRPs were completed,respectively.The dynamic model of the MR 6-DOF VRP was established by linear transfer matrix method of multibody system(Rui’s method).The transfer equation,the augmented eigenvector,the body dynamics equationstate and the space equation were derived,respectively.According to the nonlinear hysteretic characteristics of the MR damper and the working requirements of the 6-DOF VRP,three semiactive control methods for the 6-DOF VRP were proposed based on On-Off control algorithm,PID-Fuzzy control algorithm and LQG control algorithm,respectively.The numerical results showed that the proposed semi-active control method can control the damping force of the six MR legs in real time according to the attitude of the load,effectively reduce the vibration of the excitation transmitted to the load through the VRP,and achieve the purpose of 6-DOF vibration reduction in space.The vibration test results of heavy-duty main reducer VRP shown that the passive main reducer vibration reduction system and the MR main reducer vibration reduction system with semi-active control have excellent damping effect at the first pass frequency of rotor of a helicopter(25.35Hz).(5)The MR technology was introduced into the hydro-pneumatic suspension system,and a new MR hydro-pneumatic suspension system suitable for wheeled armored vehicles was proposed.Based on the design requirements of armored vehicle suspension system,the design and development of magnetorheological hydro pneumatic spring are completed.Based on the design requirements of armored vehicle suspension system,the design and development of MR hydro-pneumatic spring were completed.The properties test results shown that MR hydropneumatic spring has excellent mechanical properties and dynamic adjustable coefficient,which meets the design requirements.Based on the Bouc-Wen model of MR damper and the calculation model of gas elastic force,a nonlinear model which can accurately describe the mechanical characteristics of the MR hydro-pneumatic spring was established.In order to verify the practical application effect of the designed MR hydro-pneumatic suspension system,vehicle running experiment were carried out.The experiment results shown that the MR hydropneumatic suspension system can effectively improve the vehicle ride comfort and has high engineering value. |
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