In order to study the derailment process and dynamic performance-changing rules of vehicles on a curved track, a method of calculating critical derailment speed is proposed, which is the progressive trial method. In terms of their theoretical basis and calculation results, compared with the two traditional methods (root locus method and limit cycle method) for calculating linear and nonlinear critical speed, the advantages of this method in studying derailment are proved, and its applicable conditions are explained. Taking CRH3 as an example, the critical derailment speed on different radius curves is calculated by the progressive trial method. At the critical derailment speed, the variation laws of wheel lifting, wheel–rail attack angle and dynamic index are analyzed. The discrete elastic contact analysis is used to observe the changes in the wheel–rail contact position and contact spot during derailment. The results show that with the increase in the curve radius and critical speed of derailment, the absolute values of lateral force, vertical forces and derailment coefficient increase at the same position of the line; when the impact angle between the front wheel of the front bogie and the rail increases to more than 0.06 rad, the train is in a critical derailment state.

Based on the elastic–plastic contact theory, elastic–plastic contact finite element models for the integrated modular house by flat pack are established. The structural stress and displacement distributions are obtained. An experimental test is conducted to study the performance of the corner fitting joint of the house. The finite element analysis and experimental test comprehensively demonstrated the safety and reliability of the house structure. The results show that the most unfavorable stress point of the house is located at the corner fitting joint. When the end plate connection holes of the corner column seal are designed with through holes and internal screw holes, respectively, the fastening effect of bolting between the corner fitting and corner column using the internal screw hole is better. The reliability of the repeated disassembly and assembly of the house is verified via multiple loading–unloading simulation cycle experiments of the corner fitting joint. The results of the study provide technical support and a reference basis for the optimal design and ensuring the service performance of the integrated modular house by flat pack.

To obtain the design basis for the dynamic characteristic parameters of bridges commonly used in superconducting electromagnetic suspension transportation, a refined magnetic force calculation model is established to analyze the dynamic load characteristics of null-flux coils. The dynamic response laws of simply supported beams under four types of equivalent train loads are compared, demonstrating that concentrated superconducting coil load sequences provide sufficient accuracy for bridge dynamic factor analysis. Furthermore, parametric analyses are conducted to investigate the effects of vehicle spacing, bridge spans, and train formations on bridge dynamic factors, and the preferred range of common bridge spans and strategies for regulating dynamic factors are discussed. The results show that the optimal range for common bridge spans is 1.5 to 1.75 times the vehicle spacing. When the ratio of bridge span to vehicle distance is 1.5, first-order resonance of the bridge is suppressed, and the dynamic factors of first-order superharmonic resonance increase with the number of train formations. When the ratio is 1.75, it is necessary to increase the vertical fundamental frequency of the bridge to avoid first-order resonance within the range of train operating speeds. Matching a 24.3 m vehicle spacing with a 37.8 m span bridge, under a 14-car formation, both the first-order resonance and superharmonic resonance dynamic factors of the bridge are less than 1.8. This configuration represents the optimal design scheme for high-speed superconducting electrodynamic suspension systems in terms of vehicle spacing and standardized bridge spans.