Theoretical And Experimental Research Of Vibration Control Of Stay-Cable Using MR Damper

As the most important structural and carrying components in cable-stayed bridges, stay cables, however, are vulnerable to vibrations with large amplitudes under load action such as wind, rain, earthquake and traffic due to relate small mass, low internal.structural damping and high flexibility. Large-amplitude vibration of cables may reduce the life of cables and threaten traffic safe, and has been considered today as one of the most critical problems for cable-stayed bridges. Magneto-rheological (MR) dampers with good smart properties have significant potential to control cable vibration , and developed a new cable vibration technology research field . This thesis focuses on the test and theoretical research of the field of control of cable vibration with by using MR dampers and analyses systematily and deeply the vibration mechanism and damping effect.This thesis tested the relationship between shear stress and magnetic density of magnetic fluid,which provided by material institute of Wuhan University of Technology by using ARES - RFS magnetic fluids Instruments producted by United States . Above all, the rheological mechanics and constitutive relation and composition are introduced. Then the simply MR damper is designed initially applying MR mechanical models and working patterns and structural design criterion including damping channel, material selectiond and wrapping form of the magnet coil .and simplified the model and calculated its magnetic flux .MR damper has an excellent variable damping property such as low power requirements, large force capacity , stability and so on , at the same time its damping force can be changed by adjusting electric current applied to damper. Making MR dampers as a passive control device,using cable of 6.05 meters indoor as testing object ,you can acquired damping signals of stayed-cable by adjusting electric currents with the method of artificial shock excitation or simple harmonic excitation .Then through the signal which gathers got model damping ratio . Meanwhile, in order to compare the damper effect between MR dampers with others, in the same position installed MR dampers also were installed oil dampers and springs. Through analysis contrastly different damping devices,explored the effect damping with different damping devices and the effects of MR dampers under different electric currents , which provide a meaningful test and theoretical basis for MR dampers widely used in the actual cable-stayed bridge.