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Development of Dynamics Simulation Program for Coupling Vibration of Maglev Train-track Beam Based on UM (基于UM的磁浮列车-轨道梁耦合振动仿真程序开发)
Abstract
Based on the large general multi-body dynamics simulation and analysis platform Universal Mechanism( UM) ，a professional computer program UM Maglev is developed for the coupling vibration simulation of maglev train-track beam． The maglev train is set as multi-rigid-body model，the stiffness and damping of springs and dampers are regarded as linear or nonlinear force elements． The track is described either as 3D Timoshenko beams，or the model analysis results are imported from external finite element analysis software． The horizontal and vertical section curves，super elevation and surface random irregularities can added to the track． The control system of suspension and guidance is simulated by PID model． The Park rigid stabilization method is used to solve the differential-algebraic equations of the multi-body dynamic system． By UM Maglev，the curve passing performance，running stability and riding comfort of maglev train can be examined，the parameters of the suspension and guidance air gap of the maglev control system can be optimized，and the vibration responses of maglev track beam under the effect of dynamic maglev force can be analyzed．
... The most significant advantage of UM software is that it can regard the vehicle body, bolster, side frame, friction wedge and wheel set as ideal rigid bodies, regardless of the influence of their geometric dimensions in the dynamic analysis. In the UM software, a rigid body part was established by importing its geometric drawings, and the mass, center of mass, moment of inertia and other parameters of the structural part are assigned to the rigid body [23,24], as shown in Figure 2. Table 1 shows the key parameters of the dynamic model of the 30-t axle heavy-haul coal gondola used in this research. Table 1 shows the key parameters of the dynamic model of the 30-t axle heavy-haul coal gondola used in this research. ...
Background: In order to study the applicability of Low Vibration Track (LVT) in heavy-haul railway tunnels, this paper carried out research on the dynamic effects of LVT heavy-haul railway wheels and rails and provided a technical reference for the structural design of heavy-haul railway track structures. Methods: Based on system dynamics response sensitivity and vehicle-track coupling dynamics, the stability of the upper heavy-haul train, the track deformation tendency, and the dynamic response sensitivity of the vehicle-track system under the influence of random track irregularity and different track structure parameters were calculated, compared and analyzed. Results: Larger under-rail lateral and vertical structural stiffness can reduce the dynamic response of the rail system. The vertical and lateral stiffness under the block should be set within a reasonable range to achieve the purpose of reducing the dynamic response of the system, and beyond a certain range, the dynamic response of the rail system will increase significantly, which will affect the safety and stability of train operation. Conclusions: Considering the changes of track vehicle body stability coefficients, the change of deformation control coefficients, and the sensitivity indexes of dynamic performance coefficients to track structure stiffness change, the recommended values of the vertical stiffness under rail, the lateral stiffness under rail, the vertical stiffness under block, and the lateral stiffness under block are, respectively 160 kN/mm, 200 kN/mm, 100 kN/mm, and 200 kN/mm.
The low- and medium-speed maglev vehicle generally operates on elevated bridges with a levitation gap of only 8--10 mm, which makes it very sensitive to the vehicle--bridge coupled vibration. To conduct the corresponding modeling and simulation with common dynamics tools, an equivalent processing of the levitation system is required. Using the dynamics software SIMPACK, this paper first introduces the methods of building the multi-body vehicle system, levitation control system and the elastic bridge, respectively, in the SIMPACK railway module, levitation control module and SIMBEAM elastomer module, thus providing a modeling idea for the simulation of the active levitation and operation of low- and medium-speed maglev vehicles through multi-span bridges. It then goes on to simulate and analyze the coupled vibration of a 160 km/h low- and medium-speed maglev vehicle passing through 25 m + 25 m double-span continuous bridges. The research results show that the modeling method introduced in this paper can simulate the low- and medium-speed maglev vehicle--bridge coupled vibration phenomenon, which can be affected significantly by the low-order frequency of the elastic bridge, and can also be intensified under the bridge end impact when the vehicle enters and leaves the bridge. As the running speed of the vehicle increases and the dynamic force increases, the vertical vibration amplitudes of the elastic bridge mid-span, the car body as well as the levitation frame approximate a linear fitting with the vehicle speed. The variation amplitudes of the levitation gap and of the electromagnet current approximate a quadratic fitting with the vehicle speed.
Track irregularities have an obvious effect on the running stability and ride quality of maglev trains traveling at high speeds. We developed a measurement principle and data processing method which were applied to the high speed maglev line operating. The method, which includes partial filtering, integration, resampling of signal, and a low pass Butterworth filter, was used to calculate the irregularities of the maglev line. The spectra of the sample space were evaluated. A 7-parameter power spectrum density (PSD) function of line irregularities was fitted, based on the measured data. Analysis of the results showed that the maglev stator plane irregularities were better than conventional railway vertical rail irregularities when the wavelength was 5–100 m, and worse when the wavelength was 1–5 m. The PSD of maglev guidance plane irregularities was similar to that of cross level GRSHL (German railway spectra of high irregularity) when the wavelength was 10–100 m. The irregularities were clearly worse than cross level rail irregularities in a conventional railway when the wavelength was 1–10 m. This suggests that short-wavelength track irregularities of a maglev line caused by deviation and inclination of the stator plane should be minimized by strictly controlling the machining error of functional components during construction and maintenance.