The Research And Application Of Mechanical Property Of Mr Damper

The stay-cable is the main structure in force of cable-stayed bridges. Because of the characteristic of the relatively big flexibility, small mass and low inherent damping, which cause the cable-stayed bridge being more sensitive to external-induced vibration, it has been considered as one of the most critical problems for long spanned cable-styled bridges. At present, a common way to control the cable vibration is installing conventional dampers between cables and the surface of bridges, but these dampers are difficult to achieve the best damping effect for large-span cable-stayed bridges. In recent years, a new damper named MR damper has been developed and soon applied to the reduction of vibration in practical project. The MR damper has good variable damping characteristics and its damping force can be changed by the input current, which has made the semi-active control come into reality.Based on the test of MRD-60 share valve damper , this paper has done some researches as below:(1) The paper analyzes the vibration of cable-stayed bridge modality, which draws the wind and rain excitation is the most intense vibration.(2) The paper elaborates some important mechanical models of MR damper, the revised model is the best model to describe the phenomenon of mechanical, which can provides theoretical research and design guide for MR damper, and the paper deduces the equations of motion of cable-damper using Hamilton principle to analysis the role of damper on the cable in theory.(3) The paper analyzes the deficiencies of the existing MR damper mechanical performance test system, such as accuracy is not high, operation is complex, so the paper designs peripheral data processing circuit, constructs a new MR damper mechanical performance test, which is simple operation, accurate result.(4) Comprehensive test and research are applied to mechanical property of the ordered MRD-60 damper, and the changes of damping force are analyzed when under different variants: electric current, amplitude of vibration, and frequency. MR damper's force increased with input current, excitation frequency and amplitude, the damping force-displacement curve is good, it shows a good energy dissipation. Arrive at when the damper at the frequency of 0.5Hz, current of 1.0A and the amplitude of 25mm, the damping force is the best. These conclusions have given support to the application of the MR damper in practical engineering field.(5) As a cable-stayed bridge in Ningbo for the engineering background to study the MR damper using in the bridge, and based on the test data, analyzes the MR damper on the actual damping effects. The results shows that when the MR damper installed in cable-stayed , the maximum cable force change and amplitude change are smaller than the MR damper not installed in it, the sharpest changes in cable force reduced by 5.2%, the smallest reduction in 2.7%, the sharpest reduction in amplitude by 75.4%, the smallest reduction in the minimum for 56.8%, provided a support practical application for MR dampers in engineering.