Archive

20 July 2022, Volume 41 Issue 07 Previous Issue    Next Issue
---
Transportation+Big Data & Artificial Intelligence
Transportation Infrastructure Engineering
Transportation Equipment


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Transportation+Big Data & Artificial Intelligence

Select

Ship Path Planning and Algorithm Considering the Effect of Wind, Wave and Current XIE Xinlian1, WANG Yukuan1,2, HE Ao1, PAN Wei1, XU Xiaowei1 2022, 41(07): 1-8.  DOI: 10.3969/j.issn.1674-0696.2022.07.01 Abstract ( )   PDF (3286KB) ( )   Aiming at the problem that the influence of marine meteorological environment was seldomly considered in ship path planning, an intelligent planning method for ship paths under the effect of wind, wave and current was established on the premise of ensuring navigation safety and aiming at the shortest navigation time. Firstly, the vessel stall due to the disturbance forces of wind, wave and current was calculated. Secondly, the convex packet algorithm was used to construct a safe navigational space considering the irregularity of the obstruction zone boundary, and the initial path solution was solved based on Maklink method and Dijkstra algorithm. Then, an improved genetic algorithm with adaptive evolution of cross-mutation operator was designed to improve the convergence speed of the algorithm, and a master-slave parallel mechanism was adopted to realize the adaptive genetic algorithm’s optimization of the initial path. Finally, the proposed method was simulated and compared with the case without considering the water depth limitation and the disturbance of wind, wave and current. The results show that the path planned by the proposed method can effectively avoid unsafe navigational waters and shorten the navigation elapsed time, which helps to improve the efficiency of ship navigation and facilitate the intelligent development of ships. References | Related Articles | Metrics

Select

Dynamic Programming Algorithm Based on ARIMA Model and K-Means Clustering Analysis XU Jianmin1, ZANG Peng1, SHOU Yanfang2 2022, 41(07): 9-13.  DOI: 10.3969/j.issn.1674-0696.2022.07.02 Abstract ( )   PDF (3400KB) ( )   Finding the shortest path is one of the important steps to optimize the transportation system. In order to find the shortest path, a dynamic programming algorithm based on ARIMA model and K-means clustering analysis was established by using historical and real-time floating-car data. The algorithm was tested in the second ring road area of Chengdu using Didi travel data. The results show that the newly proposed algorithm provides high-quality time solutions with low computation. The operation time is less than 2.010 minutes, the mean absolute percentage error is less than 6.5% and the invalid value ratio is less than 20%. References | Related Articles | Metrics

Select

Shared Parking Spot Allocation and Pricing Based on Two-Way Auction Mechanism HAN Yan, DUAN Xiaoning 2022, 41(07): 14-19.  DOI: 10.3969/j.issn.1674-0696.2022.07.03 Abstract ( )   PDF (4499KB) ( )   The design of two-way auction mechanism of shared berths considering the space attributes of berths and the elastic adjustment demand of service time is of great significance to improve the participation of sharing participants and system efficiency. The two-way auction mechanism of shared berths considering the spatial and temporal attributes was designed. Aiming at the optimization of social welfare, a shared berth allocation model based on two-way auction mechanism was constructed. In order to ensure that users could truly bid, a shared berth pricing model was built based on VCG (vickery-clarke-groves) auction pricing mechanism, and the algorithm was designed and analyzed by a numerical example. The calculation and analysis of the example shows that, compared with the traditional sharing reservation mode, the two-way auction mechanism has increased the transaction success rate, the number of successful transaction units and the platform revenue by 25%, 28% and 198 yuan respectively. References | Related Articles | Metrics

Select

Stochastic Fundamental Diagram Model of Traffic Flow Speed-Density Relationship Based on Quantile Regression PAN Yiyong, GUAN Xingyu 2022, 41(07): 20-26.  DOI: 10.3969/j.issn.1674-0696.2022.07.04 Abstract ( )   PDF (4537KB) ( )   In order to simulate the traffic flow speed-density relationship accurately, stochastic fundamental diagram model of traffic flow speed-density relationship was established based on quantile regression. The quantile regression was used to fit the speed-density curve to obtain clusters of speed-density curves at different quantile levels. The hypothesis test and confidence interval calculation were carried out for the parameter values, and the fitting results were numerically analyzed. The calculation results show that the proposed model can reflect the relationship between traffic flow speed and density at different quantile levels. Compared with Greenshields quantile model and Newell quantile model, the error of Northwestern quantile model decreases by 54.1% and 33.6% respectively. The proposed method provides a methodology for the construction of traffic flow stochastic fundamental graph model, which can be extended to other future traffic flow models and has a very important application in traffic flow theory. References | Related Articles | Metrics

Select

A New Method for Vehicle Speed Planning and Model Prediction Control under V2I LIU Ping1,2, LI Zhenpeng1,2, JIANG Ping3, SHU Hang1,2, LIU Zibin1,2 2022, 41(07): 27-33.  DOI: 10.3969/j.issn.1674-0696.2022.07.05 Abstract ( )   PDF (2823KB) ( )   In order to improve the advorse effects on comfort and economy caused by the frequent switching of “stop-go” status due to the periodic change of signal lights at urban traffic intersections, a speed planning method to improve traffic efficiency was designed by combining speed planning with model predictive control in the V2I scenario. And a variable weight model predictive control method for vehicle speed control was proposed. For the proposed method, the co-simulation model was established by Prescan and Matlab / Simulink, which was compared and analyzed with the speed planning method and speed control method respectively. The results show that in terms of traffic efficiency, the network-connected bus can maintain a high speed without idling at the intersection, which saves more time than the traditional bus does. In terms of comfort, compared with the networked-PI control strategy, the maximum acceleration and deceleration of the networked-MPC control strategy are reduced by 79.22% and 93.26% respectively, and the maximum acceleration and deceleration impact are reduced by 92.73% and 96.38% respectively, which improves the driving comfort of the bus. In terms of economy, compared with the networked-PI control strategy, the average braking force and the maximum braking force of the networked-MPC control strategy are reduced by 49.79% and 96.77% respectively, making the braking occur less and the breaking situation more moderate, which improves the economy of the bus. References | Related Articles | Metrics

Select

Influence of Tunnel Pavement Color on Driving Safety LIN Zhi1, LI Jiaqi1, ZHAO Yao2, CHEN Mengting2, SU Peixun1 2022, 41(07): 34-38.  DOI: 10.3969/j.issn.1674-0696.2022.07.06 Abstract ( )   PDF (2702KB) ( )   With the development of tunnel construction in China, the problem of tunnel traffic safety has become more prominent and severe. By analyzing the braking mechanism of automobiles, it is found that shortening the reaction time of the driver plays an extremely important role in reducing the rate of traffic accidents. A system was designed to measure the reaction time of drivers under different pavement colors. Based on the simulation of the real tunnel driving environment, the relationship between different pavement color conditions and drivers reaction time was obtained through experiments. The test results show that under the most widely used black and gray pavement conditions, the driver has the longest reaction time, which is not conducive to tunnel driving safety. Based on the comprehensive analysis of the test results and the visual psychological theory of traffic color, the influence of different tunnel pavement colors on driving safety was deeply studied. Finally, it is found that the reaction time of drivers is shorter under the condition of yellow, and the color visual psychological effect of yellow is more suitable for the tunnel driving environment, which is an ideal tunnel pavement color. References | Related Articles | Metrics

Select

Signal Optimization of Pedesenian Crossing the Street Based on the Behavioral Characteristics of the Elderly ZHANG Xu1, YANG Xiaoguang2, DAI Peijia3, LI Yingshuai3 2022, 41(07): 39-45.  DOI: 10.3969/j.issn.1674-0696.2022.07.07 Abstract ( )   PDF (3626KB) ( )   In order to solve the problem that the elderly cannot cross the street safely within the total time of green light signal due to slow walking speed when passing through the crosswalk, the pedestrian crossing street signal was optimized. Three signalized intersections in Lanzhou were selected, and the field data of the elderly crossing the street were collected by photography and manual investigation. The influence degree of green flashing signal and age on the walking speed of the elderly was analyzed, and the time model of elderly crossing the street under the influence of age and green flashing signal was established. The signal timing of the existing crosswalk was optimized. The results show that the green flashing signal has a significant effect on the walking speed of the elderly. A two-stage green flashing signal mode (i.e. safe green flashing duration + shortest green flashing duration) is proposed to ensure the safety of the elderly crossing the street. References | Related Articles | Metrics

Select

Travelers Choice of Taxi and Online Car-Hailing Based on Latent Variable SI Yang1, GUAN Hongzhi2 2022, 41(07): 46-50.  DOI: 10.3969/j.issn.1674-0696.2022.07.08 Abstract ( )   PDF (2571KB) ( )   In order to study the influence mechanism of latent variables on travelers choice behavior intention, taxi and online car-hailing were taken as examples. Convenience, safety, reliability, comfort and economy were selected as exogenous latent variables, while perceived value and behavioral intention were endogenous latent variables. A willingness questionnaire of trip mode choice was designed and surveyed through web, and a structural equation model (SEM) was established. The relationship between travelers travel mode selecting behavior and various latent variables was studied. The results show that the perceived value has a significant positive effect on travelers behavioral intention, and economy and comfort are important factors that affect the perceived value. Travelers pay more attention to the convenience when choosing taxis and pay more attention to safety when choosing online car-hailing. References | Related Articles | Metrics

Transportation Infrastructure Engineering

Select

Structural Damage Identification Method Based on Mixed Principal Component Analysis under Changing Operational Environment HUANG Haibin1,2，ZANG Jinggang1 2022, 41(07): 51-58.  DOI: 10.3969/j.issn.1674-0696.2022.07.09 Abstract ( )   PDF (6223KB) ( )   In general, operational environment changes will result in corresponding changes of structural dynamic characteristics, which thereby masks changes caused by damages. In practical engineering, it is crucial to eliminate the influence of changing operational environments for structural damage identification. At present, principal-component analysis is frequently employed to achieve this purpose. However, only when data is approximately Gaussian distributed and linearly correlated, traditional principal-component analysis is very effective. When there are non-Gaussian distribution and nonlinear correlation in the data, the effect is poor. Therefore, a structural damage identification method based on mixed principal-component analysis was proposed. At first, Gaussian mixed model was applied to fit the joint probability density function of multi-dimensional (non-Gaussian distributed and nonlinearly correlated) data, resulting in a linear combination of multiple local Gaussian components. Next, corresponding principal-component analysis models were established respectively for all Gaussian components. Finally, the Mahalanobis square distance and Euclidean square distance were calculated respectively for the residuals of all principal component analysis models, which were weighted and standardized as the comprehensive damage index of the structure. The mass-spring system simulation data and the wood truss bridge test data were used to verify the proposed method. The results show that the proposed method can effectively deal with non-Gaussian distribution and nonlinear correlation among damage characteristic data, and thus eliminate the influence of changing operational environments to significantly improve the ability of structural damage identification. References | Related Articles | Metrics

Select

Application of Virtual Load Method in Calculation of Steel-Concrete Composite Beam LI Xuefeng, LU Yuanchun, ZHOU Liang 2022, 41(07): 59-63.  DOI: 10.3969/j.issn.1674-0696.2022.07.10 Abstract ( )   PDF (1024KB) ( )   Application of virtual load method in stress analysis and calculation of steel-concrete composite beam was studied. The calculation formula of temperature difference stress of simply supported composite beam based on virtual load method was derived. Combined with the effective elastic modulus method, the calculation formula of shrinkage stress of simply supported composite beam based on virtual load method was derived. Taking a 45 m span I-shaped simply supported steel-concrete composite beam as an example, the temperature difference stress and shrinkage stress of the composite beam were calculated by using the virtual load method, ANSYS finite element method and the calculation formula recommended by The Railway Composite Beam Design Regulations (TBJ 24—89), and a comparative analysis was carried out. The research results show that: for the calculation results of the temperature difference stress of the composite beam, the error between the virtual load method and the ANSYS finite element method is 1.6%, which shows that the virtual load method can accurately calculate the temperature difference stress of the composite beam. Compared with the calculation results of the calculation formula recommended by The Railway Composite Beam Design Regulations (TBJ 24—89), the shrinkage strain is more fully considered in the stress calculation formula of virtual load method. References | Related Articles | Metrics

Select

Bond-Slip Constitutive Model of Corroded Steel Strand Concrete XIE Faxiang, ZHANG Chuanlong, LI Wenxiang 2022, 41(07): 64-71.  DOI: 10.3969/j.issn.1674-0696.2022.07.11 Abstract ( )   PDF (9369KB) ( )   Aiming at the problem of bond-slip performance of corroded steel strand concrete, the influence of different corrosion rate and cover thickness on the failure mode, number and width of cracks, shape of load-displacement curve, ultimate bond strength and ultimate relative slip were analyzed by the pull-out test, and the improved bond slip constitutive model was established. The research results show that when the corrosion rate is the same, the number and width of cracks tend to decrease with the increase of the thickness of the protective layer, and the ultimate bond strength and ultimate relative slip are linearly and positively correlated with the thickness of the protective layer. Under the same thickness of protective layer, the number of cracks is basically unchanged with the increase of corrosion rate, and the width of cracks increases with the increase of corrosion rate. The ultimate bond strength and ultimate relative slip decrease linearly with the increase of corrosion rate. The simulation results show that the proposed bond-slip constitutive model of corroded steel strand concrete can better describe the bond-slip degradation behavior of corroded steel strand concrete specimens. References | Related Articles | Metrics

Select

Dynamic Response and Avoidance Distance of Pile Foundation of Cross Fault Bridge in Strong Earthquake Area FENG Zhongju1, GUAN Yunhui1, ZHANG Cong1, MENG Yingying1, DONG Yunxiu1,2 2022, 41(07): 72-80.  DOI: 10.3969/j.issn.1674-0696.2022.07.12 Abstract ( )   PDF (5276KB) ( )   In order to study the dynamic response and the avoidance distance of pile foundation of cross-fault bridge in strong earthquake area, four types of seismic waves were selected to establish the pile-soil-fault interaction model, which was based on the physical project of Haiwen Bridge. The four types of seismic waves included 5010 wave, 5002 wave, Kobe wave and El-Centro wave. The finite element analysis software MIDAS/GTS was adopted to study the variation laws of the peak acceleration response of pile foundation in the upper and lower walls of the fault, the horizontal displacement response of pile top and the bending moment response of pile. And the influence of the safe avoidance distance between pile foundation and fault on the mechanical deformation characteristics of pile foundation was also studied. The results show that the response degree of pile foundation in the upper wall of the fault is larger than that in the lower wall of the fault under the action of the four seismic waves, showing a significant “upper wall effect”. The overburden soil has obvious amplification and filtering effect on the peak acceleration of the pile body, and the peak acceleration response of pile top has hysteresis. In comparison, the peak acceleration and amplification factor of the peak acceleration at the pile top under the action of El Centro wave are the largest, the peak value of horizontal displacement at the pile top under the action of 5002 wave is the largest, and the peak value of pile body bending moment under the action of Kobe wave is the largest. It is suggested that in the seismic design of bridge pile foundation, the influence of the difference between pile foundation upper and lower walls of fault and the type of seismic wave on the bearing capacity of pile foundation shall be taken into account emphatically. It is recommended that the safe avoidance distance of the pile foundation of cross-fault bridge in strong earthquake area is 20 m (10D). References | Related Articles | Metrics

Select

Sulphate Corrosion Resistance of Alkali-Activated Cementitious Porous Concrete GAO Jingjing, FAN Xinghua 2022, 41(07): 81-88.  DOI: 10.3969/j.issn.1674-0696.2022.07.13 Abstract ( )   PDF (10511KB) ( )   The sulphate corrosion resistance of different alkali-activated materials, including alkali-activated fly ash (AAFA) and alkali-activated slag (AASL) was studied. Based on the analysis of traditional test indexes, including mass loss, cross-section size and compressive strength, combined with the micro test methods of X-ray diffraction (XRD) and scanning electron microscope (SEM), the effects of different curing ages, sulfate solution concentration and soaking time of porous concrete specimens on the sulfate corrosion resistance of porous concrete with alkali-activated cementitious materials were studied. The results show that different alkali-activated cementitious materials have different deterioration modes. Ordinary porous concrete (OPC) is mainly reflected in the attenuation of mass and cross-section size, AASL is mainly manifested by the increase of mass and the expansion of cross-section size and the main product after OPC and AASL corrosion is gypsum. AAFA has no obvious change in mass and cross-section size, whose erosion process is dealumination and alkalization of sodium aluminosilicate crystals and the formation of a small amount of gypsum, accompanied by the reduction of compressive strength. References | Related Articles | Metrics

Select

Optimization and Preparation of Slow-Release Asphalt Self-healing Capsules CHEN Kun1, YUAN Miao2, LIU Quantao3, WANG Quanlei4 2022, 41(07): 89-95.  DOI: 10.3969/j.issn.1674-0696.2022.07.14 Abstract ( )   PDF (5403KB) ( )   The preparation method of calcium alginate capsule needs to be optimized, hence the effects of preparation parameters such as sodium alginate solution concentration, emulsification shear rate and oil-water ratio on the particle size, yield strength and repair agent content of calcium alginate capsules were studied. The preparation parameters of calcium alginate capsules were optimized, and their repair effect of asphalt concrete was explored. The research results show that the optimum preparation parameters of calcium alginate capsules are sodium alginate solution with concentration of 2.0%, emulsification shear rate of 5000r/min and oil-water ratio of 1:10. The particle size of calcium alginate capsule prepared by the optimum preparation parameters is 2.16 mm, the yield strength is 13.23 n, and the content of repair agent is 76.03%. After the proposed capsule is mixed with asphalt concrete, it can gradually release the repair agent under cyclic load, so as to soften the asphalt and significantly improve the self-healing performance of asphalt concrete. References | Related Articles | Metrics

Select

Motion Field Analysis of PVA Fiber Stirring and Dispersing CAO Yuanwen1, LI Cheng1, ZHOU Bo1, HUANG Xingsheng1, ZENG Jianmin2 2022, 41(07): 96-103.  DOI: 10.3969/j.issn.1674-0696.2022.07.15 Abstract ( )   PDF (9637KB) ( )   Single filament PVA fiber can greatly improve the properties of cement-based materials. In practical engineering, PVA fiber often exists in cement-based materials in bundle form, which largely limits the effect of PVA fibers. In order to improve the dispersion quality of PVA fiber in cement-based materials, a biaxial horizontal PVA fiber stirring dispersion device was designed. The motion field model of PVA fiber stirring dispersion was established and analyzed, and the velocity and turbulence kinetic energy characteristics of PVA fiber mixture were obtained. With the variation law of the rotation speed of the mixing shaft and the mass ratio of PVA fiber to fly ash, the ideal rotation speed of the stirring shaft and the ideal mass ratio of the mixing dispersion device were obtained. The results show that the mixing and dispersing device can effectively improve the dispersing quality of PVA fiber in cement concrete. With the increase of the rotating speed and mass ratio of the stirring shaft, the velocity and turbulence kinetic energy of PVA fiber mixture gradually increase, and the amplification is first sharp and then slow. In order to save resources and ensure the stirring and dispersing uniformity of PVA fiber, the ideal stirring shaft speed is 700rpm and the ideal mass ratio is 1∶45. References | Related Articles | Metrics

Select

Influence of Road Tunnel Transforming to Cutting on Safety of Lining Structure HAN Fenglei1,2, LIU Zonghan1,2, WANG Yi3, XIAO Donghui4, QIN Zhen1,2 2022, 41(07): 104-111.  DOI: 10.3969/j.issn.1674-0696.2022.07.16 Abstract ( )   PDF (7074KB) ( )   To study the safety impact of cutting excavation unloading on the lining structure of operating tunnels, the demolition of a shallowly-buried neighborhood tunnel to a highway cutting project was taken as the research background. The Drucker Prager elastic-plastic constitutive model was used to analyze the evolution law of the deformation, stress and safety factor of the existing operating tunnel lining structure under the cutting excavation unloading by numerical simulation, and the safety impact zoning of the excavation and construction of the cutting was proposed. The results show that under the action of cutting excavation unloading and elastic resistance of surrounding rock, the tunnel floats as a whole and the walls on both sides squeeze inward, mainly vertical deformation. The maximum displacement at the arch crown is 36.77 mm. The tension region of the lining structure gradually expands from the invert upward to the vault. When the buried depth is 20m, the tensile stress reaches 3.47 MPa, and the arch foot is prone to stress concentration. The safety coefficient of the lining fluctuates greatly, and the minimum safety coefficient of the arch foot position is 1.91. In particular, it is necessary to strengthen the monitoring of the arch foot position. Referring to the code and the calculated value of each index of lining structure, the calculated residual buried depth ratio is used to divide the three zones with the impact of cutting construction on tunnel safety, and the construction suggestions for each zone are given. References | Related Articles | Metrics

Select

Stability Analysis of Tunnel Blasting Wedge Considering Blasting Effect WANG Linfeng1, HU Cailong2, ZENG Taorui1, CHENG Ping1, WU Fayou1 2022, 41(07): 112-119.  DOI: 10.3969/j.issn.1674-0696.2022.07.17 Abstract ( )   PDF (3674KB) ( )   The analysis of the stability of the tunnel wedge rock is the basis for the prevention and control of the tunnel rock disaster. Based on the blast peak acceleration attenuation law and the assumption of the wedge structure surface, the peak blasting load acting on the wedge was determined by Newtons second law, and the time-lapse blast inertia force was obtained by modifying it. The physical model and calculation model of tunnel wedge-shaped dangerous rock stability analysis were established. And the dynamic limit equilibrium method of wedge-shaped stability analysis was proposed, by which the formula for calculating the stability coefficient of wedge was obtained. Furthermore, the influence of different factors on the stability coefficient was analyzed. The calculation results show that: under the blasting load of the side wall wedge, the wedge-shaped body changes in pressure and tension with time, and the whole action time lasts about 0.3~0.4 s. Under the blasting load, the maximum peak load of the side wall wedge is 410.52 kN, and the minimum peak load is -285.69 kN. Under the blasting load, the maximum peak load of the wedge on the top of the tunnel is 140kn, and the minimum peak load is -95.23kn. The stability coefficient of side wall under single sliding surface blasting load increases by 93% in max and decreases by 63.3% in max, and the stability coefficient of double sliding surface of side wall increases by 75% in max and decreases by 47.4% in max. Under the blasting load, the stability coefficient of the single sliding surface on the top of the tunnel increases by 75.5% in max and decreases by 56.4% in max, and the double sliding surface at the top of the tunnel increases by 81.5% in max and decreases by 57.8% in max. When the explosion center distance is increased from 2 m to 5 m, the maximum difference between the two stability coefficients is 1.92. When the inclination angle of the sliding surface is increased from 28° to 58°, the natural stability coefficient is reduced by 1.5, and the impact of blasting on the stability coefficient is reduced by 4.5 in max. When the amount of explosives is increased from 28 kg to 58kg, the stability coefficient is increased by 1.65 in max. When the area is increased from 8 m2 to 20 m2, the stability coefficient is increased by 0.75 in max. Therefore, the proposed calculation method of wedge stability coefficient can better reflect and evaluate the stability of tunnel wedge under blasting load. References | Related Articles | Metrics

Select

Probabilistic Optimization Method for Weight Assignment of Debris Flow Risk Assessment LI Li1, ZHANG Shixin1, QIANG Yue1, ZHENG Zhou1, WANG Kui2 2022, 41(07): 120-125.  DOI: 10.3969/j.issn.1674-0696.2022.07.18 Abstract ( )   PDF (1580KB) ( )   Debris flow risk assessment is a typical multi-criteria decision-making problem. Aiming at the deficiencies of the weight assignment method in the debris flow risk assessment problem, an improved weight assignment method from the perspective of probability was proposed. In the improved method, the weight was regarded as a bounded uniform random variable, and the boundary conditions were calculated and obtained by equal weight method, entropy weight method and variation coefficient method. The sample weight set was obtained by Monte Carlo simulation strategy within the boundary conditions, and the final weight was solved with the minimum deviation as the optimization objective. At the same time, the proposed method was applied to the risk assessment of 20 debris flows in the Wudongde area of the Yunnan-Guizhou Plateau. The assessment results show that: the use of a single weight assignment method has certain limitations and is not universal for different types of debris flows. The proposed method is more objective for the weight assignment of each evaluation factor. 5 debris flow hazard levels are higher than the results of the traditional Liu Xilin model. References | Related Articles | Metrics

Transportation Equipment

Select

Load-Bearing Deformation Characteristics of Truck Retreaded Tire WANG Qiang1, ZHANG Jianfu2, JIANG Li1, WANG Yunlong1, HUI Shengfeng3 2022, 41(07): 126-136.  DOI: 10.3969/j.issn.1674-0696.2022.07.19 Abstract ( )   PDF (7202KB) ( )   In order to effectively improve the service performance of retreaded tire, the load-bearing deformation characteristics of 12R22.5 retreaded tire were analyzed by finite element simulation using ANSYS software, and the load-bearing deformation characteristics of retreaded tire were studied by using the load-bearing deformation test system. The variation law of load-bearing characteristics such as radial deformation, lateral deformation, grounding shape and grounding area of retreaded tires and new tires of the same type were obtained under various working conditions with tire pressure of 530~830 kPa and radial load of 10~35 kN. By use of the principle of multiple linear regression, a mathematical model calculation formula for the load-bearing radial deformation of retreaded tires was proposed, and the differences and causes of load-bearing deformation characteristics and grounding area characteristics between retreaded tire and new tire were compared and analyzed. The research results show that the load-bearing deformation characteristics of retreaded tires are consistent with those of new tires of the same type, and there are also some differences. When the tire pressure is constant, the radial deformation, lateral deformation and grounding area of retreaded tire and new tire increase with the increase of radial load. The increasing trend of deformation is approximately linear, and the increasing trend of grounding area is approximately nonlinear. Under the same tire pressure and radial load conditions, the radial deformation, lateral deformation and grounding area of retreaded tires are smaller than those of new tires of the same type. Under the working condition of constant tire pressure and low load, the radial stiffness of retreaded tire is close to that of new tire. Under the working condition of constant tire pressure and high load, the radial stiffness of retreaded tire is greater than that of new tire, and the radial stiffness difference becomes larger and larger with the increasing load. The worse the load-bearing deformation characteristics of the retreaded tire, and the shorter the remaining service life of the retreaded tire. References | Related Articles | Metrics

Select

Fracture Failure Analysis and Fatigue Life Evaluation of Locomotive Axle Box Spring ZHANG Zifan1, WANG Kexiao1, YANG Guangxue2 2022, 41(07): 137-143.  DOI: 10.3969/j.issn.1674-0696.2022.07.20 Abstract ( )   PDF (11227KB) ( )   In view of the fatigue fracture of the axle box spring of an electric locomotive, fracture analysis, dynamic stress test and finite element simulation were used to explore the fracture causes. The results show that the spring failure is fatigue fracture failure mode, and the crack source starts from the contact wear position of the first and the second ring. The frequency of the 19th order polygon of the wheel coincides with the 3rd order modal main frequency of the spring, resulting in resonance, which increases the fatigue equivalent stress of the spring. The excessive stress and the decrease of the fatigue strength caused by wear are the causes for the premature fatigue failure of the spring. References | Related Articles | Metrics

Select

Vector Control of Permanent Magnetic Synchronous Hub Motor Based on New Dead Zone Compensation HU Qiguo, ZHANG Xiang 2022, 41(07): 144-150.  DOI: 10.3969/j.issn.1674-0696.2022.07.21 Abstract ( )   PDF (5065KB) ( )   In order to improve the control performance of vehicle permanent magnet synchronous hub motor vector control system, aiming at the problems of dead zone time of inverter and the nonlinear dead time effect of components such as switch in the system, the mechanism of dead time effect and its influence on current harmonic generation were analyzed. A new dead time compensation method was proposed without current polarity detection. According to the idea of feedforward control, the dead-zone perturbation voltage observer was established and combined with linear compensation method to offset the influence of dead time effect on the vector control system of permanent magnet synchronous hub motor. Finally, the vector control simulation model of permanent magnet synchronous hub motor based on the new dead-zone compensation was built by MATLAB/Simulink simulation software. The simulation results prove that the proposed dead-zone compensation method can effectively suppress the influence of the dead-zone effect of the inverter and improve the stability of the vector control system. References | Related Articles | Metrics