The aims of Journal of Traffic and Transportation Engineering are to embody the comprehensive transportation pattern, promote the science and technology research and achievements transformation of comprehensive transportation, serve the construction of first-class discipline of transportation engineering, cultivate the scientific and technological talents in the field of transportation, and accelerate the academic research and internationality of Chinese transportation.

The existing failure criterion cannot meet the real failure prediction of adhesive structures. Thus, a stress-based fracture failure criterion was established by combining a test and simulation analysis. Five groups of ISR-7008/aluminum alloy adhesive joints with typical tension–shear ratios were designed, which then underwent quasi-static tensile tests. The initial fracture load and the maximum fracture load were obtained. The initial location of adhesive fracture failure point was determined. A simulation model of the adhesive joint was developed. The initial fracture load was applied to the simulation model. The stresses at the initial fracture point in the failure area of the five joints with typical tension–shear ratios were extracted. Through the ratio and linear combination of various stresses at the failure point, an equivalent stress calculation formula was obtained. A unified failure criterion suitable for the initial failure and subsequent failure was obtained based on the equivalent stress calculation formula. A verification test plan was designed. The validity of failure criterion was illustrated by comparing the test results and simulation results. Analysis result shows that the fracture load obtained by the simulation analysis in the 75° scarf joint is 1 717.6 N, while the fracture load obtained by the test is 1 936.4 N. The relative error is 11.3%. The simulation results are consistent with the tested failure process of bonding layer. The failure criteria established in this study are verified. The initial failure criterion and subsequent failure criterion of adhesive structures are unified in the stress-based failure criterion established in this study. The failure of adhesive joints in complex stress states can be predicted more accurately. The simulation problem of the thick layer of elastic adhesive is solved by this failure criterion, providing a certain reference for the strength design of adhesive structure in practical engineering applications.

The air damping and aerodynamic load of pulsating wind on the contact wire were respectively deduced based on the aerodynamic theory, and the aerodynamic term is added to correct the formula of fluctuation velocity of the contact wire. Through the wind tunnel test and computational fluid dynamics (CFD), the aerodynamic drag coefficient in the transverse wind environment is obtained, and the variation laws of fluctuation velocity of contact wire under different air dampings are analyzed. Based on the AR model and the structural characteristics of catenary, the pulsating wind field of catenary with temporal and spatial correlation is established. The influences of pulsating wind speed and wind attack angle on the fluctuation velocity of contact wire are analyzed through simulation. Research result shows that the air damping of contact wire caused by the static wind load is very low. When the average wind speed reaches 30m·s
−1, the air damping on the contact wire is only 0.3, and the fluctuation velocity of the contact wire is stable at about 549.1 km·h
−1. Therefore, the air damping will not have great impact on the fluctuation velocity of the contact wire. When the wind attack angle of incoming wind is 60° and the average wind speed is no more than 10 m·s
−1, the standard deviation and difference between the maximum and the minimum fluctuation velocities of contact wire under pulsating wind are less than 1 and 6 km·h
−1, respectively. In this case, the fluctuation velocity of the contact wire has little change compared with the no wind condition, and the influence of pulsating wind load on the fluctuation velocity of the contact wire is negligible. When the wind speed reaches 40 m·s
−1, the average fluctuation velocity of the contact wire decreases by 39.39 km·h
−1 compared with the no wind condition, and the standard deviation and difference between the maximum and the minimum fluctuation velocities reach 11.84 and 75.98 km·h
−1, respectively. At this point, the fluctuation velocity of the contact wire decreases and oscillates sharply, and the minimum is as low as 474.16 km·h
−1. Therefore, the higher the wind speed under pulsating wind is, the more significant the impact of pulsating wind load on the fluctuation velocity of the contact wire will be. When the wind speed remains at 30 m·s
−1 and the attack angle of incoming wind ranges from 0° to 30°, the standard deviation and difference between the maximum and the minimum fluctuation velocities are less than 1 and 5 km·h
−1, respectively. In this case, the pulsating wind load has little influence on the fluctuation velocity of the contact wire. When the wind attack angle is 90°, the standard deviation and difference between the maximum and the minimum fluctuation velocities reach 12.38 and 73.19 km·h
−1, respectively. At this point, the fluctuation velocity of the contact wire declines and oscillates drastically, and the minimum is as low as 472.91 km·h
−1. Hence, under pulsating wind, the more obvious the tendency of incoming wind is to the horizontal direction, the less influence the incoming wind has on the fluctuation velocity of the contact wire.

A quasi-static force analysis for the coupler was carried out and the longitudinal load distribution law was studied, to evaluate the change in the force state of a heavy haul freight coupler under the combined action of coupler clearance, gravity, and longitudinal traction force. A strain measurement at upper and lower traction flange roots of the coupler knuckle was designed. The relationship between the elastic stain of measuring points and traction force was obtained. The trends in bearing degrees of the upper and lower traction flanges were analyzed. A detailed force analysis of coupler was carried out. An analytical solution of equivalent forces on the load transfer sites was derived. The boundary conditions of the simulation under different traction forces of coupler were obtained. A simulation analysis of coupler was carried out. The response curve of node strain with the traction force was obtained. The reliabilities of analytical solution of the equivalent forces on the load transfer sites and simulation model were demonstrated through comparsion with strain measurements. The influences of some key parameters on the relationship between the traction force and equivalent force were analyzed. The equivalent forces refer to those on the inner wrist surface and upper and lower traction flanges. Research result shows that the upper compressive platform is stressed when the traction force is lower than 13.5 kN. The upper and lower traction flanges of the coupler are loaded simultaneously when the traction force is 13.5–1 725.0 kN. With the gradual increase in the traction force, the bearing ratio of lower traction flange goes down and approaches 0.53, while the bearing ratio of upper traction flange goes up and converges to 0.47. The bearing ratio is linearly correlated with the system parameters. The acting position of equivalent force on the inner wrist surface of coupler knuckle exerts immense influence on it. These results can lay the groundwork for studying the fatigue crack initiation and propagation simulations of couplers and can be a guidance to couplers’ service safety.

This study aims to analyze the vibration characteristics and fatigue damage of the gearbox housing of high-speed trains. A test bench for high-frequency excitation of small rollers was applied to study the vibration characteristics of gearbox housing under different conditions of vertical load and speed. The surface of the roller was processed to the 13th-order polygon with an amplitude of radial run-out of 0.05mm, which could be equaled to a 20th-order actual wheel polygon. The stress cumulative damage of gearbox housing per unit time was analyzed by the rainflow-counting algorithm and Miner linear damage rule. Analysis result indicates that the root mean squares (RMS) of vertical and lateral accelerations of each measuring point of the gearbox housing under different vertical loads are the lowest at 200 km·h
−1, affected by the resonance of the gearbox housing. The RMSs of lateral and vertical accelerations of most measurement points peak under 23 t. The resonance of gearbox at the natural frequency of 573 Hz can be stimulated by the resonance frequency of test bench at 100 km·h
−1 and 580 Hz dominant frequency of the 20-th order wheel polygon at 300km·h
−1. The stress cumulative damage per unit time at each measuring point of gearbox housing largely fluctuates when the initial speed of wheel ranges from 0 to 200 km·h
−1 and drops from 300 km·h
−1 to 0. The stress cumulative damage per unit time of each measuring point at the other speed grades undergoes only slight fluctuations. The maximum (3.72 × 10
−10) of the dynamic stress cumulative damage per second appears at the tooth surface observation hole of the gearbox while the minimum (8.29 × 10
−18) directly above the bearing of small gearbox housing. Thus, the vibration acceleration of gearbox housing is largely affected by the resonance of gearbox housing, speed grade, and deceleration of the test bench. However, the vertical load has little influence on the stress cumulative damage per unit time without resonance of gearbox housing, without deceleration of the test bench, and at the same speed grade.

The traction motor of power bogie frame of CR400BF Fuxing high-speed EMU adopted the unique four-point elastic suspension mode, and the lateral oil dampers and bump stops were installed between the motor and bogie frame. For the first time, the traction motors were used as dynamic absorbers to control the hunting stability and hunting frequency of the bogie, avoiding the elastic modal resonance of carbody. Considering the nonlinearity of suspension parameters and wheel/rail contact, a nonlinear multi-body dynamics simulation model of Fuxing high-speed EMU was established. The influence of key parameters on the hunting was analyzed by the suspension mode calculation and dynamics time-domain simulation of power vehicles. On the principle of using the traction motor as a dynamic absorber, the lateral stiffness of motor joints and the damping of oil dampers were optimized. Considering the random wheel/rail matching factors in the EMU operation, a total of 400 wheel/rail random matching conditions were combined to analyze the dynamics performances of the EMU. The long-term dynamics tracking test of the EMU on line was carried out, and the development of hunting motion of power bogie was obtained. Compared with the single-peak spectrum for lateral acceleration at the end of the bogie frame with no motor, the spectrum with motor elastically suspended on the bogie frame has two peaks, and the two dominant frequencies are on both sides of the one in the scheme with no motor. The above phenomenon is a typical feature of the dynamic absorber system. Taking the motor as a mass damper can improve the hunting stability of motor vehicles. The nonlinear critical speeds under typical wheel/rail matching conditions with different equivalent conicities exceed 500 km/h. The highest hunting frequency of motor vehicles is around 6 Hz, which is far away from the diagonal distortion modal frequency 8.5 Hz of the carbody. Therefore, the elastic resonance of the carbody caused by the bogie hunting is avoided. Under the excitation of random track irregularity, the lateral acceleration at the end of the bogie frame is less than 0.5
g; the lateral stability index is less than 2.5, and the lateral force of the wheelset and derailment coefficient meet the requirements.