The Human Simulated Adaptive Control For Vibration Isolation Based Study On Magneto-rheological Bearing

As important parts of transportation lifeline, railway bridges suffer from acceleration, deceleration or braking of high-speed trains on the railway bridge, which will create an enormous adhesion force to the bridge in span direction, especially for elevated railway bridges with a certain angle. Adhesion force is more likely to have a greater displacement on the bridge, which gives great threat to the structural safety of support system on pier-beam along the direction of bridge. To a certain extent, traditional passive pier bearing plays very good vibration isolating effects, but the stiffness and damping are not adjustable. Although the combination of adjustable damping devices and passive bearings are used to isolate the vibration for bridges, it is still not enough to adjust the damper only. The stiffness is also needed to be promptly adjusted in order to alter the natural frequency of structures, which is beneficial to improve vibration isolation, structural strength and capability. However, the compatibility of existing pier support system for cushioning and vibration isolation is limited. Therefore, it is necessary for vibration protection to use magnetic isolators with adjustable damping and stiffness(including magneto-rheological bearing and magneto-rheological damper) to replace the existing isolators. We use different control strategies to coordinate control the system of magneto-rheological bearing(MRB) between pier and beam, considering that multiple states coupling vibration for train-bridge system is a very complex. And we set the reduction of vibration energy of rain-bridge system as our control goal.Similarity theory and the finite element method are used to build the full-scale bridge model based on vibration isolation system of magnetic isolators with train braking. Based on the proposed model, a human-simulated adaptive control(HSAC) algorithm for bridge vibration isolation under the impact of train braking is designed by classifying longitudinal vibration characteristics into several statuses and choosing shear force peak of pier top, the displacement of beam and acceleration of beam as indicator. Then the simulation of longitudinal vibration control system under the condition of train braking is achieved by MATLAB. Compared with the small-scale test the effect of passive control, multi-state control and HSAC control performance for bridge vibration isolation system with train braking is verified. The main contents as follows:1. The significance of HSAC for bridge vibration isolation system based on magnetic vibration isolators with train braking is illustrated. The research status of bridge vibration isolation, the control algorithms of controllable vibrational isolators and existing problems are pointed out, and the main contents of this article are suggested.2. The bridge model and train model is separately analyzed, train-bridge-magnetic isolators coupling vibrational model is also established. The fourth order Runge-Kutta method is used to solve the force curve of train braking and restoring force of MRB. By combining spatial discretization methods and finite element model of bridges, and Newmark-β method is adopted to obtain the displacement, velocity and acceleration of train-bridge-magnetic isolators coupling vibration system.3. According to the characteristic of train braking, the vibration character of train-bridge coupling system is analyzed to obtain several vibration states of system. Considering the safety of train and bridge, We propose the optimization goal and constraints. The MATLLAB is used to build the train-bridge-magnetic isolator model. According to the different vibration state, the control characteristic model is written. Compared with passive control, multi-state control, magnetic isolator system with HSAC control will decrease the displacement peak of beam by 54%, the shear peak of pier top is reduced by 34% and comprehensive vibration isolation rate decrease by 52%, which alleviate the contradictory between reducing force and displacement response. And the acceleration of beam is inhibited and response is quick.4. We build a model test bed of MRB to verify the correctness and validity of HSAC strategy in these problems of train-bridge coupling vibration. Two aspects, including hardware platforms and software systems of the test bed system, are expatiated mainly in this dissertation. It detailed test procedures, test results and analysis of test results. Test results showed that, the acceleration of the system has some declines with HSAC MRB system, which compared with the uncontrolled MRB system. It laid a good foundation for further exploration of the coordinated control effect and parameter optimization, which is important performance parameters of the system based on multiple MRBs and magneto-rheological dampers(MRD).