Theoretical And Experimental Research On Magnetorheological Intelligent Vibration Control System For Stay Cables

At present the stay cable suffers the obvious problems of prone to large amplitude and multimodal vibration,with the increasing length of main span and stay cables,the existing damping schemes for single mode can no longer achieve the desired target of vibration control.Magnetorheological damper（MRD）,as a typical intelligent damping device,it keeps the reliability of the passive devices as well as plays a similar performance with active control benefit by its adjustability.It has the advantages of rapid response,low energy consumption and high adjustability,which has received extensive attention from domestic and international scholars.As one of the hottest research topics,the magnetorheological（MR）intelligent vibration control method for stay cables can achieve multimodal and highly efficient vibration control effects by utilizing the MRD’s adjustability.However,there are few studies on the MRD optimal design method for stay cables vibration control,the existing MRD based intelligent control algorithms are too complex to be implemented and the control systems are overly dependent on stable energy supply.These issues have greatly limited the application of such intelligent control schemes in real field stay cables vibration control projects.This paper maintains our focus on the specialized MR control scheme for stay cables vibration.It includes a series of researches on the mechanical model of the single-rod MRD,the kinetic characteristics of the stay cable damped with the nonlinear MRD control force,the solar powered module,the real-time current control system,the magnetorheological pseudo negative stiffness（MR-PNS）multi-modal vibration control method,the mechanical performance tests of MR-PNS damping device,and the damping test of model cable.The main works are as listed as follows:（1）Conducting the mechanical tests and output force modeling of the proposed single-rod MRD.The operating principle of the single-rod MRD with a novel combined compensator is introduced though revealing the influence of its internal configuration on the mechanical properties.Then the mechanical performance tests are carried out to verify the performance of this single-rod MRD,and the Sigmoid model of the MRD output force is completed based on the test results.（2）Investigating the nonlinear characteristics of MRD force and its role in the vibration control of stay cable.In this paper,the control characteristics of MRD’s non-linear force is analyzed by means of the complex eigenvalue theory,and the optimal design method of constant current MRD stay cable damping scheme is summarized.In addition,the damping effect of MRD in different vibration modes and applied current values is numerically simulated through state space method.The simulation results demonstrate the excellent modal compatibility of the proposed design method.（3）Design and fabrication of a solar powered module and a real-time control system for MRD;The composition and working characteristics of the solar powered module for MRD are described firstly,and then propose a real-time control strategy that makes the MRD exhibit pseudo negative stiffness（PNS）characteristics.Followed by the introduction of the principles and methods,the charging tests of the solar powered module on the lead battery and the mechanical tests of the MR-PNS control system are carried out.（4）MR-PNS multimodal vibration control method of stay cable;Build a control-oriented parameter model for the proposed PNS strategy,and then the Sigmoid model identified in main work（1）is coupled in to obtain the refined dynamic model of MR-PNS.In this section,the damping effect of varying PNS vibration control schemes are simulated through the State Space model of stay cable equipped with damping force.Finally,the optimal design method of multi-modal MR-PNS vibration control for stay cables is summarized.（5）Semi-active vibration control test on model cable;In the laboratory,model cable vibration control tests are set up with different MRD based damping cases.The MRD damping cases under constant current and MR-PNS case with real-time controller are set up respectively.Taking the 1^st modal control of model cable as control target,the MRD based off-line real-time semi-active control schemes is completed.The result experimentally verifies the efficiency and feasibility of the proposed single-input MR-PNS control method.Main innovations of this paper:（1）This paper proposes a design method of MRD vibration control for stay cables based on the complex eigenvalue theory,it can derive the optimal value of yield force from the characteristics and vibration state of the stay cable.The simulation results of its control effect demonstrate the excellent modal compatibility of this damping method.（2）One novel multi-mode vibration control strategy for stay cable is developed in this paper.This control strategy utilizes the PNS characteristic to increase the motion of dampers,thus increasing the energy dissipation capacity of MRDs and providing a better damping effect without increasing the installation height of dampers.（3）This paper builds a MR intelligent vibration control system with solar powered,which compose of a solar power module,a real-time current control module and a MRD.Thus it can be competent with long-term outside work.