Study Of The Properties Of Mr Damper And Optimal Desigh

Magnetorheological (MR) damper as the core device of semi-active control system, performance and characteristics were studied and basic theoretical was analysed in this study ,which have a remarkable important significance in damper structure design and optimization. Based on the MR damper udsed in cable bridges, three stages piston structure, working principle and mechanical model were studied, Through laboratory tests and actual bridge tests the performance of magnetorheological damper and effection of vibration reduction were tested.The dynamic performance and responsiveness were studied in Laboratory tests, such as damping force vs. displacement, the damping force in different conditions and response time. Actual bridge tests compared the swing and force of cable installed with uninstalled in the same external conditions.Based on the study of working principles of double-coil piston type MR damper, the magnetic fluid of MR damper was analyzed with the ANSYS finite element simulation software. It is certified that the useful efficiency of the magnetic field efficient was high when the sense of current is opposite. The function expression of the gap magnetic flux density with electric current was set up. Combined with the model of damping force and the magnetic characteristics of MR fluid, the theoretical calculation model of damping force with electric current and velocity of piston was proposed. The experiments were carried out to verify the theoretical calculation model feasibility. The experimental results illustrated that theoretical values correspond with the testing values. The method offers good help to the MR damper design and improvement.The problem of precipitation of the MR fluid is the key factor to the application of MR dampers, the stability of MR fluid affects the normal performance of MR dampers, especially the mechanical performance. The current techniques of improving the subsidence stability in MR fluid is reviewed in detail. The method of using permanent magnet inside is proposed, in order to make the MR fluid in Bingham plastic model. The improved structure of composite magnetic circuit is studied. The magnetic line of force and magnetic flux density in different conditions are compared by using finite element simulation of magnetic field through ANSYS. The present work lays down a foundation for MR damper improvement and application in the semi-active vibration control system.Taking damping force and its adjustment ratio as two objective functions,piston diameter and flank piston length as two decision variables, utilizing multi-objective genetic algorithm,The aim of optimization is to get the best performance of MR damper in finite spatial structure.