Urban Maglev Train Research Articles

Aerodynamic shape optimization of an urban maglev train

With rapid development of urban rail transit, maglev trains, benefiting from its comfortable, energy-saving and environmentally friendly merits, have gradually entered people's horizons. In this paper, aiming at improving the aerodynamic performance of an urban maglev train, the aerodynamic optimization design has been performed. An improved two-point infill criterion has been adopted to construct the cross-validated Kriging model. Meanwhile, the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used, to optimize the streamlined head of the train. Several optimal shapes have been obtained. Results reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train, and can be applied in practical engineering. Compared to the prototype of the train, optimal shape benefits from higher lift of the leading car and smaller drag of the whole train. Sensitivity analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train, and strong nonlinear relationships exist between these design variables and aerodynamic performance. The conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.Graphic abstract

An adaptive vibration control method to suppress the vibration of the maglev train caused by track irregularities

The levitation gap of the urban maglev train is around 8mm, which puts a rather high requirement on the smoothness of the track. In practice, it is found that the track irregularity may cause stability problems when the maglev train is traveling. In this paper, the dynamic response of the levitation module, which is the basic levitation structure of the urban maglev train, is investigated in the presence of track irregularities. Analyses show that due to the structural configuration of the levitation module, the vibration of the levitation gap may be amplified and "resonances" may be observed under some specified track wavelengths and train speeds; besides, it is found that the gap vibration of the rear levitation unit in a levitation module is more significant than that of the front levitation unit, which agrees well with practice. To suppress the vibration of the rear levitation gap, an adaptive vibration control method is proposed, which utilizes the information of the front levitation unit as a reference. A pair of mirror FIR (finite impulse response) filters are designed and tuned by an adaptive mechanism, and they produce a compensation signal for the rear levitation controller to cancel the disturbance brought by the track irregularity. Simulations under some typical track conditions, including the sinusoidal track profile, random track irregularity, as well as track steps, indicate that the adaptive vibration control scheme can significantly reduce the amplitude of the rear gap vibration, which provides a method to improve the stability and ride comfort of the maglev train.

Material characterization of a multi-cavity composite structure for the bogie frame of urban maglev train

Abstract Lightweight composite structure has been widely used in various applications such as aerospace, transportation, and marine. The aim of present paper was to design and fabricate a bogie frame composite element of urban maglev train. It was an attempt to use lightweight composite as the primary load carrying structure in rail transit. A combined mold which can be used in autoclave molding process was developed and a multi-cavity composite casting block was manufactured. Three-point bending test and finite element analysis (FEA) were respectively conducted to evaluate the static strength of this structure. The experimental results revealed that the glass fiber reinforced casting block could satisfy the load bearing requirement for application and the weight reduction was approximately 30.9% in contrast with the traditional metal material. Therefore, it was found that the lightweight composite has a significant potential as the load bearing structure for the rail transportation application.

EMS 방식 자기부상 시스템의 외란 저감을 위한 연구

From the past, maglev technique study(mainly for transportation like maglev) has been done. In the domestic, urban maglev train is practical steps now. High-speed maglev train(550km/h) development comes complete, followed by Japan. This year, system of High-speed maglev train(550km/h) is expected to be verified. This paper simulate FEM model for EMS(Electro-Magnetic Suspension) maglev system and verify tendency of reducing disturbance.

A New Speed Measurement Sensor Using Difference Structure

This paper proposes one new type of speed measurement sensor using difference structure to solve the problem of measurement errors resulted by the vibration of low-speed urban maglev train. By the design of the detection coils and the signal detection circuits, the sensor could fulfills the requirements of rapid and accurate detection. The experiment results show that the speed measurement sensor could effectively overcome the affect of the detection distance changes. The aim of reducing the locating errors caused by the vibration of the train body is achieved. At the same time, the measurement resolution is also increased.

도시형 자기부상열차 대차 프레임의 피로강도 평가

This study evaluated the fatigue strength of the bogie frame of an urban maglev train through fatigue analysis, cumulative damage, and fatigue tests based on a proposed fatigue evaluation method. The results of FEM analysis in which various load combinations were adopted showed that all data were under the fatigue limit of a butt welded joint made of A6005 in a Goodman diagram. The cumulative fatigue damage was calculated at the highest level from a bolt connecting the area of the electromagnetic pole in the casting block; however, the total sum was evaluated as D=0.808 based on 1×10

Fatigue strength evaluation of a bogie frame for urban maglev train with fatigue test on full-scale test rig

This study evaluated experimentally static strength for bogie frame of an urban maglev train including performing fatigue analysis, cumulative damage and fatigue test based on a developed fatigue load and as a final outcome, aimed to propose a fatigue strength evaluation method for the bogie frame of urban maglev. The results of FEM analysis adopting load combinations showed that all data was under a fatigue limit of the butt welded joint made of A6005 in Goodman diagram. The cumulative fatigue damage was calculated at the highest level from a bolt connecting area of electromagnetic pole in casting block but the total sum was evaluated as D=0.808 based on 1×107 cycles, which indicates it did not exceed the failure criteria. In addition, as the results of fatigue test, there was no crack on the any position of the bogie frame with the outcomes that corresponded to the results of fatigue test.

U 자형 전자석을 사용하는 자기부상열차의 횡진동 저감 연구

도시형 자기부상열차는 U 자형 전자석만을 사용하여 부상공극을 일정하게 유지하며 주행한다. U자형 전자석은 그 형상 특성으로 인하여 전자석 위치에 따라 안내력을 동시에 갖기 때문에 능동적 횡공극 제어가 없이도 차량을 레일에 따라 안내할 수 있는 장점을 갖는다. 그러나 횡공극을 제어하기 않기 때문에 횡진동이 증가하여 승차감 및 주행안정성에 악영향을 미칠 수 있다. 본 논문에서는 능동제어가 없이도 횡진동을 저감시키기 위한 방법으로 횡댐퍼 적용 효과에 대한 분석이 이루어진다. 이를 위하여 자기부상열차의 횡방향 고유진동특성을 우선 해석하고, 횡방향 댐퍼를 설치했을 때의 진동저감 효과 분석이 이루어진다. 정확한 횡진동 예측을 위하여 자기부상열차의 3 차원 다물체 동역학 모델을 사용하였다. 본 논문의 결과를 통해서 자기부상열차의 횡진동 저감을 위한 횡댐퍼 채택 제안에 활용하고자 한다.