Research Of Parameter Optimization On The Discrete Floating Slab Isolation System Based On Dimensionless Analysis

Metro rail transit bring convenience to people’s lives. At the same time, Metro asa mobile source of vibration seriously affects the living of residents, the structuralsafety of building and the normal operation of precision instruments. At present, thefloating slab track (FST) system take the best effect on reducing vibration and noise sothat the metro track vibration can be isolated at wider frequency range. Traditionally,the floating slab isolator is divided into rubber isolator and steel springs isolator, andthey can’t match the optimal parameters depending on the different excitation force.The isolation parameters of magneto-rheological (MR) isolator can be controlledaccording to different excitation conditions. Therefore, MR isolator provides a solutionto solve that the passive isolation parameters can’t adjustable. The practical FSTsystem studies in laboratory have some problems, such as high spending, operationaldifficulties and so on, thus, modeling studied is particularly necessary. A simplegeometric similarity does not reflect its dynamics for large-scale projects, thus,dimensionless similarity theory is an important way to solve engineering modeling.The mechanical analysis, optimization modeling, parameter optimizationsimulation and model test are applied to different vibration forms of discrete FSTvibration isolation system based on the similarity theory. The results of numericalsimulation and model test prove with each other, that the parameter optimization ofdiscrete FST system based on the dimensionless analysis is an effective research. Themain content includes the following.(1) The significance of parameter optimization on the discrete floating slabisolation system via dimensionless analysis is discussed. The research of track isolation,magneto-rheological technology and similarity theory are reviewed. Then, the mainresearch works of this paper are put forward.(2) In the straight track mainly affected by the vertical excitation loads. Thus, thediscrete FST system can be simplified a single degree of freedom (DOF) system.Further, the dynamic model established. As well as, the structure and operationprinciple of MR grease isolator is analyzed. The practical engineering system and thebench test system are combined by the dimensionless optimization model. Todetermine the optimal parameters, the procedure of parameters optimization is writtenby MATLAB. Furthermore, the optimal drive current can be determined. In a multi-frequency excitation, the root mean square (RMS) of acceleration and the RMSof the force transmitted to the foundation as the optimization goals. Through therelative acceleration transmissibility evaluate the vibration isolation system in widelyfrequency domain. Simulation results show that the RMS of acceleration is decreasedby31.41%, and the RMS of the force transmitted to the foundation is decreased by58.75%compared with the passive system. Similarly, the isolation effect afteroptimization is better than before optimization in widely frequency domain.(3) In the curved track and inclined track affected by all directions of excitationloads. Thus, the dynamic model of discrete FST system is analyzed by theestablishment of multi-DOF system. The causes and characteristics of each directionexcitation loads are analyzed systematically. The practical engineering system and thebench test system are combined by the dimensionless optimization model. The totalforce transmissibility is calculated by the weight of each director’s forcetransmissibility. The isolation effect is evaluated by the total transmissibility.(4) In order to reduce the effect of vibration on the surrounding environment andon the train, the multi-DOF discrete FST vibration isolation optimization objectivesand constraint are proposed. Furthermore, the extended Runge-Kutta method is used tosolve the dynamical equations, and the parallel genetic algorithms is designed to solvethe problem of multi-objective. The multi-DOF parameter optimization program iswritten in MATALB, and the extend Runge-Kutta method is embedded into the parallelgenetic algorithms for obtaining the Pareto solutions of multi-objective optimizationproblem. Simulation result shows that the RMS of lateral acceleration is decreased by33.49%and the RMS of the lateral force transmitted to the foundation is decreased by24.41%. As well as, the RMS of vertical acceleration is decreased by13.3%and theRMS of the vertical force transmitted to the foundation is decreased by27.47%. Theoptimized vibration isolation is better than the passive vibration isolation in a widerange of frequency.(5) The practical engineering system and the bench test system are combinedbased on the similarity theory of the dimensionless analysis. Starting from the point ofview of the dimension of the physical quantity, the similar relationship of geometric,movement, stiffness, damping and centrifugal force are deduced. The bench parametersare designed on the basis of similar relationships, and then the devices are selected andthe test bench is build. The single DOF system and the multi DOF system aresimulated separately by adjusting the position of motor. The result shows: the vibration characteristics of the prototype and similar model have preferably similarity. It’sverified that the feasibility of parameter optimization via dimensionless analysis.