Study On Dynamic Stress And Fatigue Life Of Maglev Switch Beam

Maglev switch beam, which is an important infrastructure, is the tool for train changing running line. For the electromagnetically suspended (EMS) transport systems, the guideway is surrounded by the bogies of maglev vehicles. Therefore, the switches of the maglev line should have special structure different from the wheel-rail railway switches. Maglev switch is actually a continuous flexible steel beam of large structure, complex cross section. The time of changing switch, the dynamic performance when train passes by and the fatigue life of structures are significant parameters deciding the technical level of switch. In order to ensure the safety and the comfort of maglev train, detailed research on the dynamic performance and the fatigue life of switch should be done. Based on maglev train-switch beam coupling dynamics model, dynamic stress responses of the Shanghai Maglev Line 2-way switch beam when maglev train passes are calculated. Fatigue life prediction of maglev switch beam is carried out by using the test datas. It is expected to provide useful reference for localization design of maglev switch.A dynamics model is established after analyzing the maglev switch beam, and the natural frequencies of switch are analyzed. According to the existing research results, the strctures of maglev vehicle,suspension control system and guiding control system are introduced simply. Based on above of these, maglev train-switch beam coupling dynamics model is established. Combing with structural characteristics,modal analysis results and computing results of switch, the stress analysis nodes are selected at key cross sections. Dynamic stress responses of maglev switch beam when maglev train passes are calculated. The effects of train speed, train formation, guideway irregularity for dynamic stress responses of maglev switch beam are studied respectively.Based on fatigue life prediction theory at home and aboard, according to the contents of fatigue strength in Eurocode3 (Design of steel structures) and using the test datas of Shanghai Maglev Line 2-way switch beam, the fatigue life of switch are calculated. The results indicate that the life of the node located at the upper of ribbed slab on the 3rd midspan is shortest. It's the fatigue critical point of switch beam. After further anslysis, It finds that the fatigue damage of switch is mainly caused by switching. To improve the life of switch beam, it should reduce the stress amplitude of switching process.