交通运输工程学报

Cover and Contents of Vol.25, No.2, 2025

Cover Contents

2025, 25(2): 1-1.

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Review on high-speed maglev train technology

XIONG Jia-yang, SHEN Zhi-yun, CHI Mao-ru, WU Xing-wen, LIANG Shu-lin

Abstract: From the perspective of high-speed maglev technology development, the basic principles and technical characteristics of four types of high-speed maglev trains, including conventional electromagnetic suspension (EMS), superconducting electrodynamic suspension (EDS), high-temperature superconducting (HTS) maglev (pinned maglev), and permanent magnet electrodynamic suspension (Hyperloop) were summarized. The advantages and disadvantages of the technical schemes of the four high-speed maglev trains were compared from safety performance, operating speed, operation and maintenance, and application prospects. Research results suggest that high-speed maglev transportation in China should be developed under the leadership and overall planning of the government. Based on the experience of conventional EMS train research and development, the key technologies of superconducting EDS, HTS maglev, and vacuum pipeline high-speed maglev should be included in the national science and technology development plan to build pilot bases and test lines in an orderly manner so that a comprehensive system for the research, test, standard, and product in maglev transportation can be constructed in China. Given the advantages of the socialist system with Chinese characteristics, the strategic opportunities for developing high-speed maglev transportation should be grasped. The science and technology development principles and the innovation and development process of large engineering projects should be followed based on existing research foundations to promote technological progress. The research progress of the four high-speed maglev trains should be arranged gradually and differently according to their different maturity levels to keep China's leading position in high-speed and ultra-high-speed transportation and to contribute to the strategy of a country with great transportation strength.More>

2025, 25(2): 1-23. doi: 10.19818/j.cnki.1671-1637.2025.02.001

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Research progress on high-speed EMS track system based on bibliometric analysis

YE Feng, WANG Kai, ZENG Guo-feng, SUN You-gang

Abstract: To comprehensively analyze the research progress on the high-speed electromagnetic suspension (EMS) track system, 321 pieces of Chinese and English literature from 1987 to 2023 were retrieved from core databases of Web of Science, EI, China National Knowledge Infrastructure, and Wanfang Data, covering 16 countries and regions and 59 Chinese institutions. For the first time, the bibliometric method and mapping knowledge domain built by CiteSpace were employed to analyze the research progress on the high-speed EMS track system. The development history, research effort, research themes, and hot spots of the field were analyzed and visually elucidated in light of spatial and temporal distribution characteristics of literature and keyword co-occurrence, burst, and clustering analysis. Research results show that the research on the high-speed EMS track system has experienced the incipient development stage and the preliminary development stage and is currently in the high-speed development stage. The research hot spots of the field are positively correlated with the important engineering construction and policy support. China is the backbone of research in this field, contributing 83.82% of the total English research publications. The core research institutions are mainly comprised of universities and have close relationships with enterprises. The research themes focus on seven aspects: alignment design and optimization, girder structure design, track manufacturing and installation technology, static and dynamic performance analysis for tracks, environmental load response analysis, system coupling dynamic response analysis, and track structure detection, monitoring, and maintenance. The research hot spots mainly include the vehicle-guideway coupling effect and track structure detection and monitoring, and the research on design, manufacturing, and maintenance is still slightly insufficient. The above bibliometric analysis results show that there is still much room for improvement in the research on the high-speed EMS track system. The development of China's new generation of high-speed EMS transportation at 600 km·h^-1 will be a good opportunity to enhance the level of research in this field.More>

2025, 25(2): 24-36. doi: 10.19818/j.cnki.1671-1637.2025.02.002

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Review of multimodal transport research based on bibliometrics

XU Zhi-gang, SHEN Dan-dan, GAO Ying, ZHAO Xiang-mo, YANG Min, YANG Xiao-guang, DONG Chun-jiao, YANG Zhong-zhen

Abstract: To comprehensively understand the research progress in the field of multimodal transport, bibliometric methods was adopted to systematically retrieved relevant literature from the WOS core database and the China National Knowledge Infrastructure (CNKI) database from 1990 to 2024, totaling 32111 articles, involving 2 244 authors and 1 422 keywords. Through scientific knowledge mapping, the distribution of literatures, publishing countries, research institutions, and authors were systematically analyzed and visualized. Keyword co-occurrence maps and clustering maps were used to reveal the research hotspots in this field. Emergent term analysis was conducted to predict future research directions. Research results show that multimodal transport research has gone through three stages: slow growth, steady growth, and rapid growth. The hotspots are concentrated in the analysis, planning and design, operation, and logistics of multimodal transport systems. Specifically, these include: the supply-demand relationship of multimodal transport systems, network models, the relationship between travel behavior and land use, multimodal transport network layout optimization, regional connectivity and interoperability improvement, seamless connection and efficient operation of multiple transport modes, and logistics network, transportation path optimization, and freight flow efficiency improvement. Currently, the research focuses of domestic and international scholars are highly overlapping but still differ. Domestic scholars focus more on the strategic development, structural optimization, comprehensive planning, and national urgent scenario research of multimodal transport. In contrast, international research focuses more on multimodal transport theory and the application of emerging technologies. In the future, with the development of artificial intelligence, big data, blockchain, and digital twins, multimodal transport research will move towards more integrated, three-dimensional, digital, networked, shared, and low-carbon, to achieve efficient utilization of transport spatiotemporal resources, energy, and computing power. Cross-industry, cross-field, cross-department, and cross-level collaboration and coordination will become key to driving the continuous development of multimodal transport research. This will promote resource integration and optimization, helping to build an efficient, intelligent, safe, and environmentally friendly multimodal transport system.More>

2025, 25(2): 37-60. doi: 10.19818/j.cnki.1671-1637.2025.02.003

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Fault-tolerant control for levitation systems of high-speed maglev train based on diversified basis neural networks

SUN You-gang, HUANG Zhi-chuang, LIN Guo-bin, XU Jun-qi, JI Wen

Abstract: To address the effects of system parameter perturbations, actuator faults, and left and right electromagnet coupling in high-speed maglev vehicles during long-term service, the mutual coupling relationship between left and right electromagnets and the actuator faults in the joint-structure of the maglev vehicle suspension system during the process of connecting the vehicle bodies were analyzed. A neural network method for adaptive fault-tolerant suspension control based on diversified basis functions was proposed. Diversified basis functions were introduced into neural networks, and an upper norm boundary processing method for neural networks was incorporated to address complex and discontinuous issues in the control process. Through Lyapunov functions, the fault tolerance of the proposed method against failures and its robustness to uncertain system dynamics were verified. On this basis, the ultimately uniformly boundness of the control method was proven. Experimental results indicate that when partial failure occurs in electromagnets, adaptive variables are adjusted according to fault conditions and affect control currents, thereby achieving fault tolerance performance. For steady-state signal tracking, left and right electromagnets show maximum errors of 0.2 and 0.1 mm and average errors of 0.14 and 0.09 mm, respectively. For sinusoidal signal tracking, left and right electromagnets demonstrate maximum errors of 0.2 and 0.1 mm and average errors of 0.18 and 0.10 mm, respectively. For square wave signal tracking, left and right electromagnets exhibit maximum errors of both 1.1 mm and average errors of 0.18 and 0.14 mm, respectively. The proposed method displays adaptability to faults in both left and right electromagnets, enabling rapid tracking of desired signals and ensuring operational reliability and safety of maglev vehicles.More>

2025, 25(2): 61-74. doi: 10.19818/j.cnki.1671-1637.2025.02.004

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Residual stress measurement and lifetime evaluation of railway axles by neutron scattering technology

HU Fei-fei, QIN Tian-yu, AO Ni, XU Ping-guang, SU Yu-hua, PARKER Joseph Don, SHINOHARA Takenao, SHOBU Takahisa, KANG Guo-zheng, REN Ming-ming, MA Yi-zhong, KANG Feng, WU Sheng-chuan

Abstract: To accurately predict the remaining lifetime of surface-strengthed railway axles, a damage tolerance analysis method considering three-dimensional (3D) residual stresses was proposed. By taking the induction-hardened carbon steel S38C axle as an example, two-dimensional (2D) distribution characterization of residual strain and 3D residual stress measurement were performed through comprehensive application of the neutron Bragg-edge transmission imaging and angle-dispersive neutron diffraction experiments. A numerical method was employed to implant the 3D residual stress into the axle model, and the remaining lifetime of the full-scale axle was studied by coupling the measured load spectrum, press-fit loads, and residual stresses. Experimental results show that, both axial and hoop directions present a compressive residual strain gradient layer of about 3 mm, with a maximum compressive residual strain of up to -4.5×10^-3 in the surface layer, yet a maximum strain of up to 1.0×10^-3 in the core. The maximum axial and hoop compressive residual stresses of the axle are about -500 and -303 MPa, respectively, while radial stresses overall fluctuate in the zero mean stress range. At depths beyond 4.5 mm from the surface layer, all three components are tensile stresses. The axle surface layer is subjected to compressive residual stresses, and crack propagation does not occur if the crack depth is less than 4.5 mm. Nevertheless, cracks propagate accelerates when the crack depth is greater than 4.5 mm. Different crack propagation depth thresholds lead to a larger calculated remaining lifetime for the residual stress-free condition than for the case where 3D residual stresses are taken into account. However, the axle remaining service mileage of the axle of 227 000 km under the most conservative conditions exceeds 3.5 non-destructive inspection (NDI) cycles, with a large safety margin. The experimental results can provide a scientific reference for the development and optimization of NDI cycles for surface-strengthed railway axles.More>

2025, 25(2): 75-93. doi: 10.19818/j.cnki.1671-1637.2025.02.005

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Speed sensorless MPTC of linear induction motors for rail transit based on improved SMO

HU Hai-lin, YU Shi-yan, HUANG Wei-yi, ZHAI Ming-da, YAN Zhuang-yu

Abstract: To address the high robustness of speed observation and model accuracy for speed sensorless model predictive control of linear induction motors (LIM) in rail transit, a model predictive thrust control (MPTC) strategy based on an improved sliding mode observer (SMO) was proposed. Through the improved SMO, the real-time performance and robustness of speed and flux linkage observation were enhanced, and the demand for model accuracy was lowered, thus realizing high performance model predictive control of the speed sensorless of LIM. A LIM dynamic model based on the dynamic end effect was established in the static coordinate system. A discrete model of model predictive thrust control was established. An observation method of flux linkage and speed based on the improved SMO was proposed. Subsequently, a speed sensorless MPTC system for LIM based on the improved SMO was designed. To enhance the estimation precision of speed and flux linkage, minimize sliding mode chattering, and accelerate the convergence speed, a switch function based on the continuous sigmod function was designed. Meanwhile, an improved variable exponential power reaching law was proposed to balance the contradiction between the rapid convergence and chattering of the system. The stability and dynamic performance of the improved SMO were analyzed, and the hardware-in-the-loop environment was built to verify the effectiveness of the algorithm. Experimental results show that the observation accuracy of the improved SMO is high. In the case of abrupt changes in secondary resistance and excitation inductance, the speed observation errors are 0.20 and 0.35 m·s^-1, both of which reduce by 1.4%. When the white noise perturbation with a variance of 0.01 is introduced, the maximum error is 0.20 m·s^-1, with an error rate of about 1.8%. Characterized by a fast convergence speed and less chattering of observation results, the observer exhibits a better anti-interference ability. Under the multi-speed domain conditions, the error is 0.075 m·s^-1, satisfying the performance requirements. The speed sensorless MPC system of LIM based on the improved SMO exhibits small steady state error, fast dynamic response, and good robustness performance.More>

2025, 25(2): 94-107. doi: 10.19818/j.cnki.1671-1637.2025.02.006

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Wind tunnel test study on shock wave characteristics of low-vacuum tube train

HUANG Zun-di, TAN Meng-cheng, XU Zhen-guo, CHANG Ning, FU Cheng

Abstract: To investigate the challenges faced by high-speed trains operating within low-vacuum tubes, particularly the generation of shock waves, wind tunnel tests were conducted using a magnetic levitation (maglev) train model. These tests identified the Mach number at which shock waves first appear in the flow field of tube train, as well as the positions and characteristics of the shock waves at various Mach numbers. The flow field of tube train in the wind tunnel was captured by using the schlieren system, and the interaction mechanism and shock wave characteristics between the tube train and the surrounding air were deeply explored. The actual operation of the tube train was simulated by using the computational fluid dynamics (CFD) method, and the shock wave characteristics of the wind tunnel test results and numerical calculation results were analyzed. Research results indicate that for a blockage ratio of 0.112, no shock waves occurred in the flow field of tube train when the Mach numbers were 0.5, 0.6, and 0.7. When Mach number is 0.8, shock waves first appeared in the flow field at two distinct locations: near the train shoulder and in the wake region. At the front of the train, flow separation occurs, and the airflow flows along the front of the train through the tube and the middle of the train. The cross-sectional area decreases, the Mach number increases, and a sonic line forms near the shoulder. Downstream of this sonic line, a rapid increase in gas density and pressure leads to shock wave generation. As the airflow continues through the transition between the train body and the tail, the cross-sectional area increases, the Mach number continues to rise, and flow separation occurs near the rear. The flow velocity decreases to sonic speed, resulting in a shock wave due to the sudden increase in gas density and pressure. The numerical calculation cloud map revealed the spatial distribution characteristics of the shock wave and the evolution law of flow separation. The shock wave locations in both at the train shoulder and in the wake, agreed well with the schlieren images from the wind tunnel experiments, confirming that the critical Mach number for shock wave generation is 0.8.More>

2025, 25(2): 108-117. doi: 10.19818/j.cnki.1671-1637.2025.02.007

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Definition of seaworthiness standard and construction method of seaworthiness risk indicator system for autonomous ships

ZHOU Xiang-yu, JIN Shi-qi, WANG Xin-yu, LI Zhen, NIE Sheng-zheng, LIU Zheng-jiang, ZHANG Wen-jun

Abstract: To address a series of issues such as unclear seaworthiness standards, vague criteria for assessing seaworthiness status, lack of definition for seaworthiness risks, and difficulty in identifying seaworthiness risks, the seaworthiness standards applicable to autonomous ships were clarified from three dimensions: subjective standard, objective standard, and time standard. The concepts of seaworthiness and seaworthiness risk for autonomous ships were defined. To identify the seaworthiness risks of autonomous ships, a method for constructing the seaworthiness risk indicator system for autonomous ships was proposed for the first time. Through the collection and preprocessing results of multi-source seaworthiness risk data, the extraction and clustering of seaworthiness risk factors were completed. Decoupling and reconstruction of the seaworthiness risk indicator system for autonomous ships were achieved by introducing the method of system engineering processes. Research results show that the subjective standard from the seaworthiness standards for autonomous ships can be consistent with existing standards, while the objective standard needs to be generally interpreted and expanded. Furthermore, the time standard needs to be extended to "sea voyage" for certain matters and ships with selected degrees of autonomy (DoAs), and a continuous seaworthiness management system needs to be established. The constructed seaworthiness risk indicator system for autonomous ships covers three risk categories, with initial seaworthiness assessment indicators set at 19 items, 31 items, 29 items, and 29 items and continuous seaworthiness assessment indicators at 0 item, 9 items, 28 items, and 28 items, respectively based on different DoAs. The defined seaworthiness standards and constructed seaworthiness risk indicator system for autonomous ships provide a theoretical basis and technical support for assessing the seaworthiness status of autonomous ships, formulating seaworthiness risk control strategies, developing early warning capabilities for unseaworthiness, and revealing the evolution patterns and transmission paths of seaworthiness risks.More>

2025, 25(2): 118-140. doi: 10.19818/j.cnki.1671-1637.2025.02.008

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Experimental research on remote navigation and control technology for inland waterway ships

LI Meng-xia, XU Tu-yuan, ZOU Tian-yue, LIU Chen-guang, ZHENG Mao, CHU Xiu-min, YAN Xin-ping

Abstract: To investigate the feasibility and reliability of remote navigation and control technology for inland waterway ships, a ship-shore collaboration remote navigation and control system was designed. By designing the 4G/5G dual-channel network architecture, efficient and stable ship-shore communication was established. A human-machine switching control strategy was adopted to physically implement mode transitions between manual navigation and remote navigation. Through retrofitting conventional inland waterway ships into remotely navigated ships, remote collision avoidance experiments were conducted in inland waters for typical encounter scenarios including heading-on, crossing, and overtaking. Risk evolution patterns were analyzed by using risk assessment models based on distance to closest point of approach (DCPA) and time to closest point of approach (TCPA), and existing challenges in remote navigation and control of ships were investigated. Experimental results show that the remote navigation and control technology proves applicable in narrow channel sections of inland waterways. However, the physical separation between remote operators and controlled ships leads to deficiencies in presence perception and situational awareness, hindering accurate assessment of traffic conditions and affecting operational decisions. Both perception and control links are affected by network performance during trials. The average communication delay is within one second, and the maximum delay reaches three seconds, significantly impacting collision avoidance decisions on inland waterway ships and elevating the risks of remote navigation. Remote navigation and control involve complex human-machine interaction and coordination, requiring advanced technologies including digital twins, high-precision ship motion modelling, real-time ship attitude monitoring and feedback, and communication compensation. Full-scale ship tests provide theoretical and technical support for system design. Advanced machine cognition and decision-making should be utilized in future to mitigate human-machine conflicts and improve intelligent operation.More>

2025, 25(2): 141-155. doi: 10.19818/j.cnki.1671-1637.2025.02.009

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A priority control method for special vehicles based on heterogeneous vehicle group cooperation

ZHANG Zhen, LAI Jin-tao, YANG Xiao-guang

Abstract: In a heterogeneous vehicle group environment, there is a coexistence between connected and automated vehicles (CAVs) and human-driven vehicles. To address the problems that the priority operation of existing special vehicles was vulnerable to interference and causes severe disturbances to the system, multi-objective considerations of individual priority benefits and system operation benefits were incorporated into the priority control of special vehicles. A differentiated hierarchical response mechanism for various traffic demands was developed, and the priority response levels of different vehicles' demand for right-of-way resources were determined. A hierarchical framework of centralized right-of-way allocation and distributed vehicle trajectory planning was designed. In the upper layer, right-of-way allocation decision-making was implemented based on different priority response levels of traffic demand. In the lower layer, distributed vehicle trajectory planning was achieved with the allocated right-of-way as the goal to provide the demand-responsive supply of priority right-of-way for special vehicles. To validate the effectiveness and advancement of the control method, different saturation (0.8-1.4) and different penetration rates (0.3-0.8) conditions were selected, and different priority control methods for special vehicles were compared. Simulation results show that, as for the priority level, the proposed method can guarantee the special vehicles with delays of less than 0.1 seconds, ensuring absolute priority of special vehicles in a heterogeneous vehicle swarm environment. As for the traffic efficiency at the intersection, the proposed method maintains high efficiency when the traffic demand saturation rate is below 1.0. When traffic demand saturation rate is above 1.0, the efficiency of the proposed method is significantly affected by the CAV penetration rates, and with the increment in the penetration rates, the intersection efficiency can be ensured by the proposed method in a better way.More>

2025, 25(2): 156-169. doi: 10.19818/j.cnki.1671-1637.2025.02.010

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Adaptive graph spatio-temporal synchronization for traffic flow prediction based on NODEs

SHI Xin, HU Xin-qian, ZHAO Xiang-mo, MA Jun-yan, WANG Jian

Abstract: To tackle the continuity and synchronization in the acquisition of spatio-temporal features for traffic flow prediction, an adaptive graph based on neural ordinary differential equation (AGNODE) model for spatio-temporal synchronized traffic flow prediction was proposed. According to the correlations of semantic and distance in historical traffic flow data, a two-way prior adjacency matrix was defined. An adaptive adjacency matrix with automatically adjustable weights was designed by using dynamic filtering and node embedding. With the prior adjacency matrix and the adaptive adjacency matrix, a fusion layer of the static-dynamic map was established based on the linear weighted fusion, and an adaptive spatio-temporal synchronized graph containing both temporal and spatial dimensions was constructed via the vertex features in the virtual connection layer. The neural ordinary differential equations (NODE) were employed to solve the graph convolutional network (GCN) and then form the graph convolutional NODE (GCNODE). The AGNODE model was constructed by utilizing the time-aligned solution step and double-stacked GCNODE. Using the California freeway public traffic datasets (PeMS04 and PeMS08), combined with indicators such as the mean absolute error (MAE), root mean square error (RMSE), and training and inference time, the AGNODE model was tested and verified. Analysis results show that compared with those of the optimal baseline model of the spatio-temporal graph ordinary differential equation (STGODE), the MAE and RMSE of the AGNODE model in the single-step prediction (5 min) decrease by 3.6% and 2.8% on PeMS04, and by 2.2% and 1.7% on PeMS08, respectively. In the multistep predictions (15, 30, and 60 min), the MAE and RMSE of the AGNODE model decrease by an average of 3.0% and 2.4% on PeMS04, and by an average of 3.6% and 1.2% on PeMS08, respectively. As the network layer increases, the MAE and RMSE of the AGNODE model decrease by 5.3% and 2.6%, while those of the STGODE model decrease by 0.7% and 0.6%, respectively. The training and inference time of the AGNODE model on PeMS04 and PeMS08 decrease by 11.4% and 7.5%, respectively, compared with those of the attention-based spatial-temporal graph convolutional network (ASTGCN). Moreover, the AGNODE model can achieve better prediction accuracy with an additional time of no more than 7.7% compared to STGODE. Therefore, the AGNODE model can exhibit strong capabilities in spatio-temporal modelling and parameter adaptation, accurately predict the short-term traffic flow, and provide reliable flow information and decision basis for traffic participants.More>

2025, 25(2): 170-188. doi: 10.19818/j.cnki.1671-1637.2025.02.011

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Selection of logistics network nodes based on cloud warehousing under uncertain demand

WU Di, SHI Shuai-jie, ZHANG Ya-ting, ZHENG Jian-feng, LIU Bao-li

Abstract: In order to reduce the effects of uncertain logistics demands on the efficiency and stability of urban delivery network, the problem of selecting logistics network nodes based on cloud warehousing was investigated. Realistic factors such as the capacities of cloud warehouses and vehicles, as well as the stock-out guarantee rate, were taken into account, and a mixed-integer nonlinear stochastic optimization model aiming to minimize the total cost of cloud warehouse leasing and distribution was constructed. A three-layer hybrid algorithm model was designed by integrating plant growth simulated algorithm, neighborhood search algorithm, dynamic programming, and genetic algorithm. In the outer framework, the number and location selection of cloud warehouses were optimized based on an adaptive plant growth simulated algorithm. In the middle framework, the service relationships between cloud warehouses and demand points were optimized based on the improved neighborhood search algorithm incorporating the volume-distance-cost accumulation clustering operator. In the inner framework, the delivery vehicle routes were optimized based on the dynamic programming savings algorithm, and the trunk vehicle routes, the rental areas of each cloud warehouse, and the replenishment cycles were optimized based on the genetic algorithm. Research results show that the total cost of the solution obtained by the algorithm designed reduce from a maximum of 3.673 4 million yuan to 3.508 2 million yuan compared with existing algorithms, and the reduction range is between 2.48% and 4.50% compared with different algorithms. When the number of cloud warehouses and demand points is the same, the distance between production and sales areas is negatively correlated with the trunk transportation cost, and positively correlated with the rented area of cloud warehouses and the replenishment cycle. The unit rent of cloud warehouses is positively correlated with the trunk transportation cost, and negatively correlated with the rented area of cloud warehouses and the replenishment cycle. The more concentrated the distribution of cloud warehouses and demand points, the lower the distribution cost of the cloud warehousing system. Under the same distribution, the number of demand points is positively correlated with the number of selected cloud warehouses and the rented area of cloud warehouses. The research conclusions can provide decision-making references for the design of cloud warehouse logistics networks.More>

2025, 25(2): 189-203. doi: 10.19818/j.cnki.1671-1637.2025.02.012

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Robustness design of multi-span through tied-arch bridge considering systemic hanger failure

FAN Bing-hui, SUN Qi, CHEN Bao-chun, CHEN Kang-ming

Abstract: To investigate the dynamic impact of systemic hanger failure on the multi-span through tied-arch bridge, firstly, three numerical calculation methods were employed to simulate the effects of hanger breakage: the LS-DYNA restart method, the element birth and death method, and the full-dynamic analysis method. The simulated effects were then compared with dynamic response data of the hanger breakage test to identify the optimal method for modeling systemic hanger failure. Secondly, to enhance the robustness and prevent progressive collapse in multi-span through tied-arch bridge structures, two structural systems were proposed: the simply-supported continuous structure and the rigid integral tied-arch structure. The failure simulation method was employed to compare the dynamic response of the remaining structure under systemic hanger failure before and after structural transformation. Additionally, the Simple-Johnson-Cook model was utilized to simulate the damage process of the bridge and determine the final damage mode of the structure. On this basis, the progressive collapse and damage mechanism of the structure under systemic hanger failure was further investigated. Research results show that the error between the simulation results and the test data of the LS-DYNA restart method is relatively small, enabling better simulation of conditions when the hanger experiences instantaneous damage. For the simply-supported continuous structure, in the event of systemic hanger failure, the final damage extent of the bridge system is the lowest, and the force transmission path is extended, effectively delaying the damage process of the structure, reducing the risk of progressive collapse accidents, and providing additional time for traffic evacuation. However, for the rigid integral tied-arch structure, due to the high initial stiffness, stress concentration may occur, leading to premature local failure of the bridge system. Consequently, the simply-supported continuous structure can be utilized in the design of newly constructed multi-span through tied-arch bridges or readily applied to enhance the robustness of existing bridges through the installation of replaceable joints on pier tops.More>

2025, 25(2): 204-217. doi: 10.19818/j.cnki.1671-1637.2025.02.013

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Corrosion degradation of shear performance in friction-type connections with high-strength bolts for steel structures

LU Lin-feng, NIE Shao-feng, DING Song-lin, MA Zhong-yi, LI Rui, WANG Wei, RAFTERY Gary

Abstract: In order to investigate and compare the effects of external and internal anti-corrosion coating on the shear performance in friction-type connections with high-strength bolts, a relevant experimental study was carried out. The preset conditions included the presence or absence of anti-corrosion coating on the friction surface, the presence or absence of external anti-corrosion coating, and the maintenance of external anti-corrosion coating. Under these conditions, shear performance tests before and after corrosion were carried out on 43 specimens featuring friction-type connections with high-strength bolts in 17 groups. Calibration tests were conducted on the anti-slip coefficient of the friction surface painted with epoxy zinc-rich primer, alcohol-soluble inorganic anti-rust and anti-slip primer for bridges, and sandblasted friction surfaces. Test results show that the anti-slip coefficient of sandblasted friction surfaces is 0.44, which does not meet the recommended code value. The anti-slip coefficient of the friction surface coated with epoxy zinc-rich primer is 0.27, and it is 0.50 when the friction surface is coated with alcohol-soluble inorganic anti-rust and anti-slip primer for bridges. Both values are higher than the recommended code value. A C4 atmospheric corrosion environment was artificially simulated, and an alternate wet and dry copper accelerated acetic acid salt spray test (CASS) was carried out. One-time corrosion tests were completed for specimens with sandblasted friction surfaces, epoxy zinc-rich primer, alcohol-soluble inorganic anti-rust and anti-slip primer for bridges, external anti-corrosion coating, and no corrosion protection. A second corrosion of the external anti-corrosion coating following maintenance was performed. The test results show that the acceleration of laboratory accelerated corrosion tests is predictable and controllable. Significant degradation of shear performance in friction-type connections with high-strength bolts is not prevented by external corrosion coatings, with a degradation range of 4.9%-19.0%. The corrosion degradation of the shear bearing capacity of the connection can be delayed after the friction surface is treated with an anti-corrosion coating. The anti-corrosion ability of the external anti-corrosion coating of the steel structure will gradually decrease after maintenance. Through the anti-slip tests of friction-type connections with high-strength bolts, the effect of corrosion on the shear performance of friction-type connections with high-strength bolts under different preset conditions (internal and external anti-corrosion coating, external anti-corrosion coating maintenance) in a simulated C4 atmospheric corrosion environment was investigated. It is concluded that the degree of degradation of the shear bearing capacity of friction-type connections with high-strength bolts without external anti-corrosion coating is about 1.5-1.8 times that of the specimens with external anti-corrosion coating. In the C4 atmospheric corrosion environment, the reduction of the anti-slip coefficient is the main factor affecting the degradation of the shear bearing capacity of friction-type connections with high-strength bolts with external anti-corrosion coating. The loss of the pre-tightening force of high-strength bolts is the main reason for friction-type connections with high-strength bolts without external anti-corrosion coating.More>

2025, 25(2): 218-234. doi: 10.19818/j.cnki.1671-1637.2025.02.014

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Moisture diffusion law of cracked HDPE sheath for bridge cables under alternating action of ultraviolet and fatigue loads

MENG Qing-ling, DUAN Hao-chen, WANG Bao-lin, GUO Xiao-yu, WANG Hai-liang, ZHANG He

Abstract: To reveal the moisture diffusion mechanism of cracked high density polyethylene (HDPE) sheaths in cable-bearing systems of bridges in service, prefabricated-slot sheaths were subjected to alternating ultraviolet and fatigue loads to generate fatigue cracks. Based on this, moisture diffusion tests on cracked sheaths were conducted, the equivalent crack area of the sheath was defined, and the variation laws of moisture diffusion flux and diffusion coefficient were revealed. Research results show that only ultraviolet exposure does not significantly change the moisture diffusion behavior of the cracked sheath. In contrast, when the fatigue load cycles increase from 4.50×10⁴ to 1.35×10⁵, the moisture diffusion flux and diffusion coefficient both increase by 6.16% under only fatigue load. When the crack area of the specimen is small, the moisture diffusivity of the sheath is mainly influenced by fatigue load. Considering alternating ultraviolet and fatigue loads, compared to only fatigue loads, single and two alternating actions can increase the moisture diffusion flux and diffusion coefficient by 4.80% and 8.57%, respectively. The sequence of alternating actions also affects the moisture diffusion law in the cracked sheath. Ultraviolet conducted at first can enhance the effect of fatigue load, increasing the moisture diffusion flux and diffusion coefficient by 8.42% under the same fatigue load cycles. When ultraviolet exposure is applied later, the results for single alternating action are similar to those under only fatigue loads, while two alternating actions only increase the values by 4.49%. Therefore, it is considered that only ultraviolet or fatigue loads are insufficient to fully explain the moisture diffusion law in cracked sheaths during service. Predicting the moisture accumulation law within the cable sheath requires a comprehensive consideration of the coupled effects of ultraviolet and fatigue loads. These findings can provide a basis for the maintenance and repair of bridge cables, thereby extending the service life of cable-supported bridges.More>

2025, 25(2): 235-251. doi: 10.19818/j.cnki.1671-1637.2025.02.015

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Multi-objective optimization algorithm for upper stiffened double-deck steel truss girder bridge based on response surface

WANG Ling-bo, GUO Xin-jun, ZHAO Peng, ZHU Cheng-long

Abstract: To optimize the design parameters of the upper stiffened double-deck steel truss girder bridge to ensure structural safety and reduce the engineering workload of the superstructure, an improved AdaDelta algorithm based on the response surface method suitable for multi-objective optimization was proposed. Based on a bridge serving both highways and railways, a multi-scale hybrid element model was established for the initial design parameters, and its calculation accuracy was validated. Based on the structural and mechanical characteristics of the bridge, the height of the upper and lower chords, the height of the truss, the maximum length of the stiffened vertical rods, and the thickness of the bridge deck were selected as the structural parameters to be optimized. In addition, the mid-span live load deflection, the maximum tensile stress of stiffened chords, the maximum bending stress of the bridge deck, the maximum compressive stress of lower chords at the top section of piers, the maximum stabilizing compressive stress of web rods, and the engineering workload of the superstructure were selected as the objective functions. A set of response surface fitting equations reflecting the nonlinear relationships between the parameters to be optimized and the objective functions was established. The improved AdaDelta algorithm was applied to optimize the design parameters of the upper stiffened double-deck steel truss girder bridge and compared with the optimization results of PSO and NSGA-Ⅲ. Analysis results show that the response surface method can accurately fit the numerical relationship between the parameters to be optimized and the target response function. The lightweight equation can achieve a fitting accuracy exceeding 97% and a variation coefficient below 1%. This approach significantly enhances computational efficiency while maintaining accuracy. The improved AdaDelta algorithm retains the fast convergence speed and low fluctuation characteristic of the traditional AdaDelta algorithm. By introducing a dual-weight control criterion based on satisfaction and importance, the optimization results become more targeted and applicable for engineering projects. The multi-objective optimization satisfaction results can be improved by an average of 6%. After the optimization of design parameters, the structural internal forces are redistributed. The mid-span live load deflection, the maximum tensile stress of stiffened chords, and the maximum bending stress of the bridge deck increase by 10.37%, 4.65%, and 4.99%, respectively. The maximum compressive stress of the lower chord at the top section of piers and the maximum stabilizing compressive stress of web rods decrease by 0.86% and 4.34%, respectively, and the engineering workload of the superstructure decreases by 4.11%. The project cost is greatly reduced under the premise of ensuring structural safety. The proposed algorithm is efficient and user-friendly. The weights can be flexibly adjusted according to specific optimization requirements to achieve design decisions oriented toward different goals. It is suitable for application in the optimization design practice of bridges in other systems.More>

2025, 25(2): 252-269. doi: 10.19818/j.cnki.1671-1637.2025.02.016

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Optimization on vibration reduction of longitudinal constraint system in suspension bridges based on KPSO algorithm

LI Guang-ling, GAO Huan, HAN Wan-shui, LAN Guan-qi

Abstract: To achieve optimization on vibration reduction of the longitudinal constraint system in the suspension bridge under the wind and traffic flow loads during operation, the Kriging-particle swarm optimization (KPSO) algorithm was constructed by integrating the Kriging surrogate model and the particle swarm optimization (PSO) algorithm with global optimization capability. Based on the existing wind-vehicle-bridge coupling vibration system, the longitudinal vibration characteristics of a large-span suspension bridge under normal wind, random traffic flow, traffic flow braking, and typhoon loads during operation were analyzed. The parameter sensitivity of the rigid central buckle and the variable parameter viscous damper to vibration reduction of the suspension bridge was analyzed. By taking the longitudinal displacement at girder end and tower top, as well as the relative longitudinal displacement at suspender cable end and girder end, as the indicators and taking the control efficiency of the cumulative value of the indicators as the goal, the vibration reduction optimization design of the longitudinal constraint system in the suspension bridge under different weight coefficients of load levels was carried out. The analysis results show that the estimation error between the sample test value and the calculated value obtained from the surrogate model is less than 5% in the case, indicating that the constructed KPSO algorithm can provide an algorithmic basis for the optimal design of the longitudinal constraint system in suspension bridges. The rigid central buckle has a significant vibration reduction control effect on the relative longitudinal displacement at suspender cable end and girder end, while the damper at girder end only has a significant vibration reduction control effect on the longitudinal displacement at girder end and the relative longitudinal displacement at cable end and girder end of suspenders near the girder end. However, it is not conducive to the longitudinal vibration reduction of short suspenders in mid span, and the relative longitudinal displacement at the short suspender cable end and girder end increases with a rising damping coefficient and decreases with a higher velocity index. The longitudinal vibration reduction efficiency of suspension bridges in descending order is as follows: rigid central buckle+damper system, only rigid central buckle system in mid span, and only damper system at girder end. Therefore, according to the principle of minimum damping force, the longitudinal constraint system of rigid central buckle+damper [1.0 MN·(m·s^-1)^-0.2] for the suspension bridge is recommended.More>

2025, 25(2): 270-282. doi: 10.19818/j.cnki.1671-1637.2025.02.017

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Seismic response of ballastless track system with Ⅲ-type slab on bridge considering traveling wave effect

ZHANG Peng-fei, XU Lang, TANG Qiang-qiang, WANG Cheng-long, YAN Bin

Abstract: To analyze the influence of the El-Centro seismic wave considering the traveling wave effect on the dynamic response of the track-bridge structure, and investigate the force and deformation laws of bridge components when the longitudinal resistance of fasteners and the longitudinal stiffness of the top of the fixed bearing pier/abutment were changed under the traveling wave effect, a simply supported beam bridge was selected as the research object. Based on the finite element method and the principle of beam-slab-rail interaction, a ballastless track model with a Ⅲ-type slab for a simply supported beam bridge of 11-32 m was established on the ABAQUS platform. The direct acceleration method was used to simulate the traveling wave effect. According to the results of dynamic response analysis, recommended values for corresponding influencing factors were proposed. Research results show that when the seismic traveling wave effect is considered, the force and deformation laws along the longitudinal direction of the bridge structure remain basically consistent under different operating conditions. However, seismic excitation considering traveling wave effect causes the displacement of the track-bridge structure along the traveling wave propagation direction. With the increase in the apparent wave velocity, the variation laws of maximum longitudinal stress/force in components differ and should be analyzed in conjunction with apparent wave velocity. The maximum longitudinal displacement of components increases as apparent wave velocity decreases, with the most significant change observed in the longitudinal displacement of the top of the fixed bearing pier/abutment, with an increase of 49.8%. When fasteners with longitudinal resistance of 15.0 kN·set^-1 or 10.0 kN·set^-1 are used, the force and deformation of components are nearly the same, and the difference in maximum displacement is less than 5.0%. When low-resistance fasteners with 4.1 kN·set^-1 are used, the tensile stress in components other than the rail increases by over 31.6%; component displacement increases by 236.0%, and the relative displacement of the track slab increases by 948.0%. Therefore, fasteners with longitudinal resistance of higher than 10.0 kN·set^-1 are recommended. The longitudinal stiffness at the top of the fixed bearing pier/abutment is positively correlated with the maximum stress/deformation of components, with the greatest increase found in the longitudinal displacement of the track slab, reaching 87.2%. Therefore, it is suggested that the longitudinal stiffness at bearing on the bridge should not exceed a coefficient value of 1.0. The above research results can provide a theoretical reference for the seismic design of ballastless track structures with a Ⅲ-type slab on bridges in earthquake-prone areas.More>

2025, 25(2): 283-295. doi: 10.19818/j.cnki.1671-1637.2025.02.018

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Study on mechanical behavior of unsupported sections of ballast track based on wheel-rail dynamics model

NIU Liu-bin, ZHAO Yan-feng, LIU Wan-li, ZHOU Wei, JIANG Shu-guang

Abstract: To study the wheel-rail mechanical behavior and rail deflection deformation characteristics under the excitation of unsupported sleepers of ballast tracks, the wheel-rail dynamics simulation model was constructed based on the typical Chinese ballast track structure and the suspension system parameters of in-service vehicles. The contact state between the sleepers and the ballast in the unsupported area was refined. The wheel-rail interaction behaviors of the vehicle passing through 1-3 sleepers at a running speed of 200 km·h^-1 under symmetrical and asymmetrical sleepers were numerically simulated. The mapping relationships of the wheel-rail vertical force, the maximum rail deflection displacement, track dynamic irregularities, the change rate of the wheel load, and other parameters in the unsupported area with the number and depth of unsupported sleepers were demonstrated. Research results show that the unsupported sleepers change the supporting stiffness of the foundation under the left and right rails, thereby causing significant differences in the deflection displacements of the left and right rails and the vertical forces of the wheel-rail and resulting in dynamic irregularities of the track such as dynamic height, triangular pits, and horizontal irregularities, as well as a large rate of change in wheel load. The maximums of the above parameters are related to the depth and the number of unsupported sleepers and the contact state between the unsupported sleepers and ballast. Due to the stiffness of the track itself, the above parameters no longer change when the number of unsupported sleepers is greater than 1.6 mm. Under the cases of asymmetrical unsupported sleepers, the difference in the unsupported sleepers of the left and right rails mainly forms dynamic horizontal irregularities, and its amplitude is negatively correlated with the rate of change of the wheel load on the unloaded side. At the same number of unsupported sleepers, they both increase with the number of the unsupported sleepers, and the maximum change rate of wheel load is about -0.28 under the case of one-side three unsupported sleepers. Under the cases of symmetrical unsupported sleepers, the amplitudes of the dynamic height irregularities of the left and right tracks are comparable, while the amplitudes of the dynamic horizontal irregularities are relatively small. When there are symmetrical unsupported sleepers, the maximum change rate of wheel load is approximately 0.03. The research results of this paper can provide scientific references for the wheel-rail interaction in the unsupported sleeper area, the analysis of the differences in the dynamic and static track irregularities, the identification of the characteristics of initial unsupported sleepers, and early warning technologies.More>

2025, 25(2): 296-310. doi: 10.19818/j.cnki.1671-1637.2025.02.019

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Preparation and early-strength mechanism of CA mortar for rapid repair and replacement of slab ballastless track filling layer

GAO Yi, LI Hao-xin, MA Cong, YANG Xu, DONG Bi-qin, LI Hui, DU Yan-liang

Abstract: Targeted at major repair and replacement of China railway track system (CRTS) Ⅱ type slab filling layers in high-speed railway, fast-hardening cement emulsified asphalt (CA) mortar satisfying the construction window time and early performance was developed. Magnesium phosphate cement-based emulsified asphalt (MCA) mortar and sulphate aluminium cement-based emulsified asphalt (SCA) mortar were prepared by using magnesium phosphate cement and sulphate aluminium cement combined with cationic emulsified asphalt. The Bingham model was employed to fit the rheological parameters, quantifying the yield stress and plastic viscosity of the slurry. A dynamic elastic modulus tester was used to measure the 7 d elastic modulus, and accelerated leaching tests were conducted to quantify the leaching rates of Mg²⁺/Ca²⁺. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS) microstructural analysis was used to reveal the interfacial interaction mechanism between the asphalt phase and cement hydration products. Research results show that the final setting time of both systems is under 60 min, satisfying the maintenance window time of high-speed railways. The 2 h compressive strength of MCA mortar is 11.5-29.3 MPa, and that of SCA mortar is 5.1-9.3 MPa. Both have a 28 d elastic modulus exceeding 7 GPa. As the A/C ratio increases, the fluidity of MCA drops from 170 mm to 140 mm, with the yield stress rising to 9.284 Pa. SCA shows better fluidity and outperforms MCA in volume stability and water resistance. Microstructurally, the asphalt film intertwines with struvite and ettringite to form a dense network. Therefore, SCA-type CA mortar is preferable for rapid repair of the CRTS Ⅱ filling layers due to its superior early strength, water resistance, and ionic stability.More>

2025, 25(2): 311-321. doi: 10.19818/j.cnki.1671-1637.2025.02.020

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Performance and whole life cycle environmental impact assessment of cement-stabilized permeable recycled aggregate subgrade

YANG Tao, XIAO Yuan-jie, WANG Xiao-ming, CHEN Yu-liang, MENG Fan-wei, HE Qing-yu, YANG Jian-xiong

Abstract: To promote the widespread application of recycled aggregates derived from building demolition wastes (BDWs) in road engineering, a whole life cycle assessment method was applied. The cost and environmental impacts of the blending proportions of recycled aggregates and auxiliary cementitious materials on cement-stabilized permeable recycled aggregate (CPRA) during the four stages of raw material production, engineering construction, road maintenance, and service completion were further analyzed. In combination with laboratory compressive strength, permeability coefficient, four-point bending test, freezing resistance test, and compression resilience tests, the CPRA was compared with the traditional cement-stabilized aggregate (TCSA) subgrade materials from multi-performance and multi-dimensional perspectives. Research results show that the compressive strength and permeability coefficient can meet the requirements of China's road standards when the CPRA is used with recycled aggregate partially substituted for natural aggregate. The proportion of recycled aggregate reaches 60% by optimizing the ratio of cementitious materials in the mixture. The CO₂ emissions of cement-stabilized materials during raw material production account for 87%-91% of the total CO₂ emissions throughout the whole life cycle. The CO₂ emissions during cementitious material production account for 95% of the total CO₂ emissions of raw material production. The CO₂ emissions can be effectively reduced by using auxiliary cementitious materials to partially replace cement and employing recycled aggregates. Compared with the three groups of materials with 0 recycled aggregate content, the three groups of CPRA with 30% recycled aggregate content can reduce the total cost by 8%-20% and CO₂ emissions by 3%-15%. The three groups of CPRA with 60% recycled aggregate content can reduce the total cost by 24%-34% and CO₂ emissions by 3%-23% compared with the three groups of materials with 0 recycled aggregate content. The replacement of cement with auxiliary cementitious materials with a proportion of 10%-32% decreases the CO₂ emission of the mixture by 8%-17% but increases SO₂ and NO_x emissions by 14%-81% and 21%-106%, respectively. The total cost of CPRA is lower than that of TCSA. The research indicates that when the dosage of cementitious materials is controlled within the range of 7%-8%, the CPRA demonstrates superior whole life cycle carbon emission performance. The research findings will provide a reference for the application of recycled aggregates from BDWs in fully permeable subgrade as well as the measurement of carbon emission data and the design of material ratios.More>

2025, 25(2): 322-339. doi: 10.19818/j.cnki.1671-1637.2025.02.021

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Wind tunnel test and numerical simulation for vortex-induced vibration of EMUs using scaled model

QIN Ting, YAO Yuan, SONG Ya-dong, FAN Chen-guang

Abstract: In view of the sustained swaying of the train tail of the CR200J power-centralized electric multiple unit (EMU) in a single-track tunnel, a 1∶25 scaled train model for the CR200J EMU was constructed to explore the generation mechanism and aerodynamic characteristics of train tail swaying. The lateral vibration of a single-degree-of-freedom carbody was measured by a wind tunnel test. A fluid-structure coupling numerical simulation platform for a wind tunnel model was established by the large eddy simulation (LES) method, and the simulation results were verified by the wind tunnel test. Under the conditions with and without the fluid-structure coupling vibration, the wake vortex structure and aerodynamic response were analyzed. Research results show that the lateral aerodynamic force frequency (vortex-induced frequency) is linearly related to the wind speed when the carbody is assumed to be fixed and the fluid-structure coupling vibration is not considered. Meanwhile, the size of the lateral aerodynamic force is related to the aerodynamic shape of the carbody and the wind speed. When the fluid-structure coupling vibration is considered, the lateral vibration amplitude is positively correlated with the wind speed. The lateral aerodynamic force frequency is locked to the lateral natural vibration frequency of the carbody due to the frequency locking effect of vortex-induced vibration. In this case, the carbody is subject to the vortex-induced resonance, and the lateral vibration is aggravated. Additionally, in contrast to the conditions of non-fluid-structure coupling simulation, the lateral vibration of the carbody results in a backward displacement of the high vorticity region and the separation point of the boundary layer and causes them to be closer to the nose tip. This causes an increase in the force arm of the lateral force generated by the vortex shedding, which further amplifies the yaw moment of the carbody and aggravates the vibration. The fluid-structure coupling can change the size and frequency of the aerodynamic load and further affect the dynamic response of the carbody. Therefore, the fluid-structure coupling vibration method combining train dynamics and aerodynamics is necessary for the analysis of the train tail swaying.More>

2025, 25(2): 340-350. doi: 10.19818/j.cnki.1671-1637.2025.02.022

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Analysis of dynamics performance and wheel wear on a high-speed EMUs equipped with herringbone gears

SONG Ye, QI Ya-yun, ZHAN Li-chao

Abstract: A vehicle dynamics model incorporating the complete traction transmission system was built. Herringbone and helical gears were adopted in modeling the transmission system. A comparative analysis was conducted on the influence of the two gear transmission systems on wheel-rail contact parameters and vehicle dynamics performance. The effect of herringbone gear meshing on wheel wear in the transmission system was analyzed. Analysis results show that herringbone gears increase the meshing stiffness of the gear pairs, resulting in smoother torque transmission. Herringbone gears effectively reduce both the lateral forces between wheels and rails and the lateral displacement of wheelsets. The maximum lateral displacements during traction were 8.9 and 5.7 mm in the helical and herringbone gear models, respectively, indicating a reduction of 35.9% in the herringbone gear model. Herringbone gears significantly reduces the axial forces in the gears, with the maximum axial forces of helical and herringbone gears reaching 4.50 and 2.85 kN, respectively. When herringbone gear transmission systems are applied in high-speed EMUs, wheel wear becomes more concentrated after new wheels are paired with new rails, which make it difficult to achieve uniform wheel profile wear. Under straight-line conditions, wheel wear in the herringbone gear model increases by 5.96% compared to the helical gear model. Wheel wear is strongly affected by the traction torque. Harmonic torque affects wheel wear to some extent, and its increase lead to higher wear. The helix angle has a minor effect on wheel wear. The research provides a theoretical basis for the design of herringbone gear transmission systems in high-speed EMUs.More>

2025, 25(2): 351-360. doi: 10.19818/j.cnki.1671-1637.2025.02.023

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