The dynamic interaction of vehicles/bridges is an important part of the research field of the Electromagnet Suspension (EMS) maglev train. However, multiple factors affect the dynamics of the coupling system, which increases the complexity of the vehicle-bridge coupling system, and makes it difficult to analyze. Herein, combining the advantages of theoretical derivation and numerical calculation, a fast and accurate analysis method of maglev vehicle and bridge system is proposed to analyze the influence of bridge and controller on the dynamics of the maglev system. This work is directed to the Changsha maglev express line, in which the mathematical equations for the vehicle- bridge system is presented. Then the influence of the parameter on the system is analyzed. Finally, the vibration experimental test system is set up, and the vibration test of the maglev vehicle bridge is tested by the test scheme, and the experimental results data are given. The test results of vibration acceleration are in good agreement with the calculation results of the proposed method, which verifies the accuracy of the model and the analysis method. Therefore, the research in this paper can provide theoretical guidance for Maglev engineering, and the analysis method in this paper can also be used in the study of other vehicles, such as the high-speed maglev train.

In the maglev transportation system, the track beam may vibrate under the dynamic levitation force of the maglev vehicle due to its own elastic characteristics, which may cause the vehicle to vibrate. At present, the general method of suppressing vibration is to improve the stiffness, density, damping of the bridge, and the accuracy of track installation, which will result in higher construction costs. In this article, the simulation analysis of the vehicle-rail coupling vibration is carried out from the perspective of suspension control characteristics. Through theoretical derivation, a mathematical model is established, and the mechanism of the vehicle-bridge coupling system vibration is analyzed through simulation. The internal influence of the main parameters of the controller on the system vibration is discussed. Theoretical analysis and simulation research show that the mismatch between the structural parameters of the track beam and the controller parameters will cause coupled vibration, while adjusting the parameters to match the track beam structure can suppress vibration to a certain extent. Taking the 25-m simply supported beam of Changsha Maglev Express as the research object, the vehicle-bridge coupled vibration characteristics test under 75–140-km/h operating speed is carried out, and the dynamic response of the vehicle and the bridge frame is obtained. Dynamic experiments show that proper controller parameters can maintain a stable suspension of the vehicle. This research provides theoretical and experimental references for vehicle-track coupled vibration suppression and maglev transportation system optimization.

The fault detection of the suspension system in a maglev train is of great importance for its operational safety and reliability. However, in random matrix theory (RMT), the size of the random matrix direct impacts the result of the mean spectral radius (MSR). In this paper, a state-of-the-art fault detection method for suspension systems is proposed using optimized RMT. The random matrix with the largest number of eigenvalues is obtained by reshaping the original data, with the help of the auto-correlation length from the correlation analysis. Finally, the optimized MSR is applied to detect the fault. The results of the experiment illustrate that the proposed method is applicable and effective.

In order to meet the technical requirements of non-destructive measurement for the internal stress of ferromagnetic materials represented by cold-rolled steel sheets during the rolling control process, the paper presents a novel method for the nondestructive measurement of ferromagnetic materials based on inverse magnetostrictive principle. By improving the traditional U-shaped sensor, a transmissive quadrapole layout is proposed. The corresponding excitation module and fast signal processing system for dynamic measurement were developed and the test system for detecting innerstress of ferromagnetic material was constructed in the laboratory. The relationship between the magnetic flux with the principal stress was found by experimental investigation and the sensitive correlation of the two was verified under the laboratory measurement conditions without strong electromagnetic interference. The influence of measurement results by sensor parameters such as sensor angle, amplitude of excitation current, variation of air gap were discussed in detail and a method was proposed to decrease the power supply instability caused by the change of the airgap. The experimental results show that the transmission quadrupole layout makes the test system exhibit a good linear response to the internal stress in the specimen. The feasibility of the magnetic detection method of internal stresses in ferromagnetic material was verified through the experiment.

It will be realized that automatic alarm and prediction for abnormal conditions such as structural cracks, if the state of bogie structure can be monitored during the operation of Maglev train, which can improve the safety performance of maglev train. The inherent characteristics of the structure are unaffected by the environment, such as modal frequency and damping. When the structure changes, the inherent characteristics change, so these changes can be used to diagnose structural cracks. Due to the system and measurement error existed, the sensitivity coefficient of each order modal frequency of the crack is different, so it is difficult to identify the fault by using the traditional threshold method. In view of this problem, the Principal Component Analysis (PCA) is introduced to extract the feature, and then the pattern classification is carried out by support vector machine (SVM). Simulation results show that this method is feasible.

The switch is an integral part of the changeover system of the maglev vehicle. It is prone to generate coupling vibration in low-speed and static suspension conditions, which may result in the bogie hit the tracks and endanger the safety of the train in severe cases. Therefore, it is very important to study and grasp the movement laws of the suspension system and the switch. In this paper, the suspended magnetic field is analyzed using numerical simulation and theoretical derivation, and the model of Vehicle-coupled-switch vibration in maglev system is established base on single magnet suspension system model. The coupled vibration of the single-point system model during static suspension process is simulated, and the intrinsic influence of the main parameters of the switch on the system vibration is discussed. Finally, the effectiveness of the simulation calculation is illustrated by the practical experimental tests results. The study has a certain valuable as reference for improving the design of switch.