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SSRN 2024年

作者： Qing, caolin Jie, Shaolong Yue, Zurun Mao, Shuai Zhai, Zhongang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China College of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Shijiazhuang University Shijiazhuang050035 China College of Transportation Shijiazhuang Tiedao University Shijiazhuang050043 China

The deformation of the subgrade surface caused by frost heave and thawing settlement is the main cause of railway subgrade deformation in the frozen area, and controlling the deformation of the subgrade surface by reducing the freezing depth is the key to ensure the stability of train operation. Based on the measured temperature field and deformation field of the subgrade of the HQTJ-5 bid section of the Haqi passenger special project, and taking the freezing depth and frost heave deformation in the center of the subgrade on the minimum temperature date as the control standards, the simulation models of the subgrade temperature field and the deformation field were established, and the thermal insulation effects of 13 different types of subgrade surface structures were explored. The results show that under the premise of not considering the hot blanket effect of asphalt mixture layer, both asphalt mixture and cement-stabilized gravel have thermal insulation effect, and laying on the surface layer of subgrade bed can reduce the freezing depth. Appropriately increasing the 2.36-4.75mm particles in the asphalt mixture can reduce the thermal conductivity, the rubber powder cement stabilized gravel can further improve the thermal insulation capacity, and when the surface structure of the foundation bed adopts "10cm thick Ac-16 c asphalt mixture reinforced layer + 30% rubber powder cement stabilized gravel", the thermal insulation effect is the best, and the freezing depth can be controlled within 0.97m, and the frost heave deformation can be controlled within 3.23mm. The structure is of great significance to the design of thermal insulation and waterproof roadbed in the frozen area. © 2024, The Authors. All rights reserved.

关键词： Structural optimization

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Snow Load Shape coefficients and Snow Prevention Method on Stepped Flat Roofs

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SSRN 2023年

作者： Zhang, Zhibo Ma, Wenyong Li, Qiang Li, Sai State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang051132 China Key Laboratory of Road and Railway Engineering Safety Ministry of Education Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Hebei 050043 China

Excessive snow load and nonuniform snow deposition are the main factors leading to building collapses. The snow load shape coefficient represents the dimensionless snow load, and its value is related to the unbalanced distribution of snow. There are differences in the codes of different countries for applying snow load shape coefficients on stepped flat roofs. Therefore, through the combination of field measurements and numerical simulations, this study probed into the snow accumulation processes and snow load shape coefficients on stepped flat roofs, and thus proposed a viable design option to minimize the potential for any drift. It is found that the windward drift on the lower roof is similar to a "triangle" shape, while the downwind drift is close to being evenly distributed. Based on these, the equation of snow load shape coefficients is summarized, which combines with the discrepancies between counties’ codes and the regularity of snow distributions. In this study, the dynamic grid technology under the Eulerian framework is used to predict snow accumulation on stepped flat roofs. The formation mechanism of snow erosion and deposition in each process is analyzed with the wind field. Finally, an effective approach to prevent snow on stepped flat roofs is conceived. © 2023, The Authors. All rights reserved.

关键词： Snow

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Establishment of Dynamic Model of axle Box Bearing of high-speed Train under Variable Speed conditions

Research Square

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Research Square 2021年

作者： Liu, Yongqiang Wang, Baosen Zhang, Bin Yang, Shaopu School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China School of Traffic and Transportation Shijiazhuang Tiedao University Shijiazhuang050043 China College of engineering and computing University of South Carolina ColumbiaSC29208 United States State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

This paper establishes a dynamic model of the bearing rotor system of a high-speed train under variable speed conditions. Different from previous works, the proposed model simplifies the contact stress and considers the compensation balance excitation caused by the rotor mass eccentricity. The angle iteration method is used to solve the challenging problem that the roller space position cannot be determined in bearing rotation. The simulation results show that the model accurately describes the dynamics of bearing under varying speed profiles that contain acceleration, deceleration and speed oscillation stages. The order ratio spectrum of the bearing vibration signal indicates that both single frequency and multiple frequency in simulation results are consistent with that in theoretical results. Experiments of bearing with outer ring fault and inner ring fault under various operating conditions are presented to verify the developed model. © 2021, cc BY.

关键词： Dynamic models

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Ride comfort and Energy Harvesting of Inflatable Hydraulic-Electric Regenerative Suspension system for Heavy-Duty Vehicles

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SSRN 2023年

作者： Zhang, Buyun Luo, Minglu Li, Shaohua Tan, chin-An Liu, Zhiqiang Automotive Engineering Research Institution Jiangsu University Jiangsu Zhenjiang212013 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China Department of Mechanical Engineering Wayne State University DetroitMI48202 United States School of Automotive and Traffic Engineering Jiangsu University Jiangsu Zhenjiang212013 China

Heavy-duty vehicles (HDVs) experience severe vibrational environments when traveling on rough roads and dissipate considerable energy in the suspension system because of the dampers working, and the intense vibrations induced by the road roughness are transmitted to the vehicle body and the cockpit, greatly affecting the driver's ride comfort. Therefore, an inflatable hydraulic-electric regenerative suspension (IHERS), which can mitigate the vehicle’s vibration and recover some energy dissipated by the damper, was proposed in this study. The configuration and working principle of the IHERS was then interpreted and the corresponding mathematical model was established based on the hydraulic system's pressure drop and flow relationship. A half-car model with 5-degree-of-freedom including the cockpit was developed to assess the performance of the IHERS-equipped HDVs. Structural and non-structural parametric study of the influences on the IHERS was conducted in depth to better understand the damping forces. Simulation examples were taken to investigate the performance of energy recovery and dynamic behaviors of this type of vehicle, comparing to those of a vehicle with a traditional passive suspension. The results indicate that the equivalent damping coefficients range of IHERS fits within the HDVs’ damping force range. Moreover, the damping force can be adjusted by tuning the external resistance of IHERS, which can be used for control of semi-active suspension. The energy conversion efficiency increases up to 41.9% when the IHERS-equipped HDV travels on the class-c road at 20 m/s. The design of IHERS can improve the ride comfort, reducing vertical acceleration of the cockpit by 23.3% comparing to a traditional suspension, of an HDV. © 2023, The Authors. All rights reserved.

关键词： Energy harvesting

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Feature extraction and classification algorithm, which one is more essential? An experimental study on a specific task of vibration signal diagnosis

arXiv

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arXiv 2021年

作者： Liu, Qiang Zhang, Jiade Liu, Jingna Yang, Zhi Department of Electronic and Communication Engineering North China Electric Power University Hebei Baoding071003 China College of Mathematics and Information Science Hebei University Hebei Baoding071002 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

With the development of machine learning, a data-driven model has been widely used in vibration signal fault diagnosis. Most data-driven machine learning algorithms are built based on well-designed features, but feature extraction is usually required to be completed in advance. In the deep learning era, feature extraction and classifier learning are conducted simultaneously, which will lead to an end-to-end learning system. This paper explores which one of the two key factors, i.e., feature extraction and classification algorithm, is more essential for a specific task of vibration signal diagnosis during a learning system is generated. Feature extractions from vibration signal based on both well-known Gaussian model and statistical characteristics are discussed, respectively. And several classification algorithms are selected to experimentally validate the comparative impact of both feature extraction and classification algorithm on prediction performance. copyright © 2021, The Authors. All rights reserved.

关键词： Failure analysis

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The Effect of High-Temperature Deformation Twinning on the Work Hardening behavior of Fe-38mn Alloy During Hot Shear-compression Deformation

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SSRN 2023年

作者： Sang, Deli Xin, Xiaoli Fu, Ruidong Li, Yijun Jing, Lei College of Materials Science and Engineering Shijiazhuang Tiedao University Hebei Shijiazhuang050000 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China State Key Laboratory of Metastable Materials Science and Technology Yanshan University Hebei Qinhuangdao066004 China Northwest Institute for Nonferrous Metal Research Xi’an710016 China

The effect of high-temperature deformation twinning on the work hardening behaviors of Fe-38Mn alloy during hot shear-compression deformation was investigated. The flow curves for hot shear-compression deformation of Fe-38Mn alloy exhibit the characteristics of continuous work hardening. The deformation was uniform shear-compression deformation with no significant strain localization, but the shear action gradually increased with the increase of strain rate. Benefited from such deformation characteristics, the dynamic microstructure evolution was pioneered by "bulged" mechanism and had geometric and sub-grain migration characteristics, which was continuous dynamic recrystallization in nature and accompanied by a large number of micro-shear bands and deformation twins. Particularly, the work hardening rate curve is classified into five stages considering the deformation twinning during hot shear-compression deformation. © 2023, The Authors. All rights reserved.

关键词： Shear bands

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Nonlinear Dynamics Analysis and Vibration Reduction of Two Sandwich Beams connected by a Joint with clearance

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SSRN 2024年

作者： Guo, Zhenkun Jiang, Shuai Shen, Yongjun Jiang, Guoqing Xiao, Boya Xu, Qi Li, Meng Beijing Engineering Research Center of Monitoring for Construction Safety Beijing University of Civil Engineering and Architecture Beijing100044 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Zhejiang Sci-Tech University Hangzhou310018 China Key Laboratory of Microgravity Chinese Academy of Sciences Beijing100190 China School of Mechanics and Aerospace Engineering Southwest Jiaotong University Chengdu610031 China

The dynamics and vibration reduction characteristics of the hinged sandwich beams with clearance fixed at both ends is studied theoretically and experimentally. A transverse and torsional spring system with clearance is used to equivalent the joint model. The homogenization method is used to equivalent the core layer and Rayleigh-Ritz method is utilized to derive the mode function of the interconnected sandwich beam by using a sequence of orthogonal polynomials. The nonlinear motion equation of the two jointed sandwich beam structure with clearance is derived by the application of the Hamilton principle and then solved using an improved Newmark integration approach. In order to validate the accuracy of the natural frequency and vibration mode, the finite element model is established. This paper examines the impact of clearance on the amplitude-frequency response and vibration transmission of a two jointed sandwich beam structure, it is found the hinged sandwich beams show obvious nonlinear characteristics and intermittent vibration transmission phenomenon due to the clearance. Moreover, the vibration transmission analysis reveals that the existed clearance demonstrates significant vibration reduction effect, for which an experiment is conducted to validate the results. In general, this work proposes a novel approach for modeling sandwich structures with clearance with improved vibration reduction performance. © 2024, The Authors. All rights reserved.

关键词： Homogenization method

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Mitigation of Shady-Sunny Slopes Effect on Subgrade by Photovoltaic Sheltered Boards in Permafrost Regions

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SSRN 2024年

作者： Tian, Run-Ze Li, Xiao-Kang Zhang, Yu Zhang, Lu-Xin Yue, Zu-Run Li, Xu Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong University Beijing China School of Traffic and Transportation Lanzhou Jiaotong University Lanzhou730070 China China Railway Northwest Science Research Institute Co. Ltd China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

The temperature disparity between shady and sunny slopes leads to uneven subgrade deformation in permafrost regions. In response, this paper introduces a novel photovoltaic sheltered boards (PSB) subgrade and conducts a numerical investigation into its mitigation of shady-sunny slopes effect. The study commences with developing a two-dimensional heat transfer model, accounting for the coupled boundary of solar radiation and air convection. The numerical model was validated through monitored temperature data from the Beiluhe observation station. Subsequently, the study calculates the temperature distribution of the exposed subgrade to illustrate the effect of shady-sunny slopes and identify influencing ***, this study explores the feasibility of equalizing differential temperatures through insulated boards (IB), which refers to the traditional subgrade with laid IB and the novel PSB subgrade with suspended IB. Finally, the mitigation effects of temperature difference of two modes are compared, considering key parameters including solar radiation, subgrade alignment, wind speeds, and reflection rate. The study concludes that solar radiation significantly influences the shady-sunny slope effect, followed by subgrade direction, wind speed, and reflection rate. Both IB and PSB modes can reduce thaw depths and mitigate the shady-sunny slope effect by blocking solar radiation, with PSB demonstrating superior effects due to heat convection among an adjustable suspension height. Additionally, PSB results in a reduction of over 3 ℃ in the average annual temperature of the sunny slope and is recommended to be suspended at a height exceeding 5.3 cm in the research area. In summary, the PSB subgrade effectively mitigates shady-sunny slopes and is recommended with comprehensive consideration of mitigation performance and carbon emissions. © 2024, The Authors. All rights reserved.

关键词： Heat convection

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Study on mechanical properties and failure characteristics of rock mass with weak interlayer subjected to freezing–thawing treatment

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Arabian Journal of Geosciences 2022年第10期15卷 1-9页

作者： Fang, Zhichun Zhu, Zhengguo Zhang, Shuai Wu, Siqi Ma, chaoyi Wang, Renyuan State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuag Tiedao University Shijiazhuang People’s Republic of China State Key Laboratory for Track Technology of High-Speed Railway China Academy of Railway Sciences Beijing People’s Republic of China Hebei Province Technical Innovation Center of Safe and Effective Mining of Metal Mines Shijiazhuang People’s Republic of China School of Traffic and Transportation Shijiazhuag Tiedao University Shijiazhuang People’s Republic of China

Influenced by the geological activity, there are a lot of weak interlayers in the surrounding rock of tunnels along railway in china, and the severe cold climate has a great influence on the engineering properties of rock in cold region. To better understand the influence of interlayer dip and freezing–thawing (F-T) cycles on the mechanical properties and failure characteristics of tunnel surrounding rock and therefore providing a theoretical basis for the tunnel support design, rock samples with different dips of weak interlayer and different F-T cycles were prepared in laboratory, and the triaxial compression test was carried out. The results show that (1) the deformation of hard rock part with weak interlayer is small, while the failure of soft rock interlayer is more severe. When the dip angle of the interlayer is small (β = 0° and 30°), the fracture crack is nearly parallel to the dip angle of the interlayer after rock failure. When the dip angle of the interlayer is large, the fracture surface of the rock mass and the interlayer present an X-shaped intersection. The more F-T cycles, the stronger the damage degree of rock mass. (2) Triaxial compression strength (TcS) and elastic modulus of rock mass decrease first and then increase with the increase of dip angle of interlayer, and the compressive strength and elastic modulus are the minimum when the dip angle of interlayer β = 45°. compared with the rock mass with horizontal weak interlayer, the compressive strength decreases by 35.27%, and the elastic modulus decreases by 34.84%. (3) F-T cycles have a significant deterioration effect on the mechanical properties of rock mass. The bearing capacity of rock mass decreases with the increase of F-T cycles, but the plastic deformation capacity increases. There is a negative exponential correlation between TcS, elastic modulus, and F-T cycles and a positive linear correlation between peak strain and F-T cycles.

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Load Distribution Uniformity of Assembled Emergency Steel Bridge Pier columns

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SSRN 2024年

作者： Liu, Zi-Yu chen, Shi-Tong Zhi, Mo-Mo cheng, Shuai-Qi Fan, Xin Collaborative Innovation Center for Performance and Security of Large-scale Infrastructure Shijiazhuang Tiedao University Shijiazhuang China Hebei Eng. Innovation Center for Traffic Emergency and Guarantee Shijiazhuang Tiedao University Shijiazhuang China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

Throughout the utilization of assembled emergency steel bridge piers, there is a significant discrepancy in the load carried between different columns, which can lead to premature failure of individual columns and potentially trigger the collapse of the entire structure. currently, there is no mature method for calculating and implementing load distribution. Based on an improved Fourier series and energy principle, this paper proposes a universal calculation method for the load distribution of columns in assembled emergency steel piers. A specific assembled emergency steel pier is selected as the research subject to conduct model tests and simulation experiments. Through mutual verification of theory, experiments, and simulations, this study analyzes the key factors affecting the load distribution of columns, examines the mechanisms and patterns of their impacts, and explores general principles for the even distribution of loads. The research shows: As the column height or diameter-to-thickness ratio increases, the proportion of load borne by the corner columns and transverse edge columns increases, while the central and longitudinal edge columns see a reduction in their load proportions. A pier-beam linear stiffness ratio based on an overall consideration is proposed. As the height of the columns or the diameter-to-thickness ratio increases, the pier-beam linear stiffness ratio tends to decrease. Using the coefficient of variation of column loads as the standard for evaluating the pier-beam linear stiffness ratio, the recommended threshold for the application of the pier-beam linear stiffness ratio in engineering should be between 3 and 3.86. © 2024, The Authors. All rights reserved.

关键词： Steel bridges

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