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SSRN 2024年

作者： Su, Mingming Zhou, Zhiming Wang, Han Non-destructive Testing Laboratory School of Quality and Technical Supervision Hebei University Baoding071002 China National and Local Joint Engineering Research Center of Metrology Instrument and System Hebei University Baoding071002 China Hebei Key Laboratory of Energy Metering and Safety Testing Technology Hebei University Baoding071002 China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace Engineering Xi'an Jiaotong University Xi’an710049 China

Interpenetrating phase composites (IPCs) were prepared by connecting open-cell aluminum foam (AF) and epoxy resin (EP) in three-dimensional space. Silica powder was added to epoxy resin to improve the compressive and three-point bending properties of IPCs. In the bending test, acoustic emission (AE) was applied to track the bending deformation of the samples, and k-means clustering algorithm was applied to identify the damage modes. When the content of silica powder was 100 wt.%, the compressive and bending properties of IPCs were the highest. The X-type shear band and EP/AF debonding appeared in compression failures of AF and IPCs, respectively. The AE clustering results showed that under bending load, AF contained plastic deformation of matrix and fracture failure modes, while IPCs included plastic deformation of foam matrix, EP/AF debonding and EP failure modes. © 2024, The Authors. All rights reserved.

关键词： Epoxy resins

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Effects of the Cuo Additive Nanoparticles on the Internal Strain Homogenization and Microstructure Evolution in Ag-Sno2 Composites

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SSRN 2022年

作者： Li, Guijing Ma, Yuanyuan Feng, Wenjie Zhang, Chuanzeng Yan, Zhen Fang, Xueqian Tian, Ruilan Shijiazhuang Tiedao University Shijiazhuang050043 China Provincial Collaborative Innovation Center of Mechanics of Intelligent Materials Hebei China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures China Department of Civil Engineering University of Siegen SiegenD-57068 Germany Department of Engineering Mechanics Germany

Stress concentration caused by reinforcements has very unfavorable effects on the metal matrix composites, which will inevitably induce localized strains and crack initiation. In this paper, an effective approach is presented to relieve stress concentrations near the reinforcements in metallic composites. The Ag-SnO2 contact materials with CuO additive are prepared by electroless plating combined with powder metallurgy method. The CuO nanoparticles in-situ formed on the SnO2 reinforcements are adopted to relieve local stress concentrations near the Ag/SnO2 interfaces and promote strain homogenization. The mechanical properties, deformation characteristics and microstructure evolution of the Ag-SnO2 composites without and with CuO additive are systematically studied by experiments and numerical simulations. The results show that the CuO nanoparticles formed on the surfaces of the SnO2 reinforcements dramatically improve the mechanical properties of the Ag-SnO2 composites, particularly the plasticity at a higher loading rate. It is demonstrated that the dislocation tangle around the CuO nanoparticles effectively relieves the adverse effect of the stress concentration near the SnO2 and results in the strain homogenization in the Ag matrix. Furthermore, the damage evolution of the Ag-SnO2 composites without and with CuO nanoparticles is investigated by the Gurson-Tvergaard-Needleman (GTN) models under uniaxial tension. The nucleation and growth of voids at the interfaces of the Ag-SnO2 composites are numerically simulated and discussed. This study provides a fundamental basis for developing novel high-performance metal matrix composites. © 2022, The Authors. All rights reserved.

关键词： Stress concentration

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A mechanism-data dual-driven approach for predicting profile changes in rails

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Wear 2025年 578-579卷

作者： Yadi Yang Jianxi Wang Yang Li Wenjie An Jiasheng Cai Key Laboratory of Roads and Railway Engineering Safety Control Ministry of Education Shijiazhuang Tiedao University Shijiazhuang 050043 PR China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang 050043 PR China

Accurate prediction of rail profile changes is crucial for scientifically formulating rail wear mitigation strategies, maintaining track reliability, and ensuring economic benefit. However, traditional models based on rail wear mechanisms are limited in prediction accuracy due to their idealized assumptions. While possessing strong nonlinear fitting capabilities, data-driven models often lack interpretability and rely on large amounts of high-quality training data. To address these challenges, this paper proposes a novel method that integrates the advantages of both approaches to predict rail profile changes. Utilizing a prototype network, a rail profile change model is pre-trained with simulation data and then fine-tuned using measurement rail profile data through transfer learning. K-fold cross-validation and noise augmentation are employed to enhance the model's prediction accuracy and robustness. The study results indicate that for tracks with curve radii between 400 and 600 m, the precision of 10 random prediction trials exceeds 90 %, with standard deviations of Mean Squared Error ( MSE ), Root Mean Squared Error ( RMSE ), Mean Absolute Error ( MAE ), and Mean Absolute Percentage Error ( MAPE ) being 0.03397 mm 2 , 0.04261 mm, 0.0204 mm, and 0.175 %, respectively, demonstrating excellent predictive accuracy and stability. Compared to models using only measurement data, this method achieves reductions in average MSE , RMSE , MAE , and MAPE by 30.60 %, 11.76 %, 12.94 %, and 10.45 %, respectively.

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Causal inference approach to appraise long-term effects of maintenance policy on functional performance of asphalt pavements

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arXiv 2024年

作者： You, Lingyun Guo, Nanning Long, Zhengwu Wang, Fusong Si, Chundi Diab, Aboelkasim School of Civil and Hydraulic Engineering Huazhong University of Science and Technology Hubei Province Wuhan430074 China State Key Laboratory of Mechanical Behaviour and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Province Shijiazhuang050043 China Department of Civil Engineering College of Engineering Fahad Bin Sultan University Tabuk71454 Saudi Arabia Department of Civil Engineering Aswan University Aswan81542 Egypt

Asphalt pavements as the most prevalent transportation infrastructure, are prone to serious traffic safety problems due to functional or structural damage caused by stresses or strains imposed through repeated traffic loads and continuous climatic cycles. The good quality or high serviceability of infrastructure network is vital to the urbanization and industrial development of nations. In order to maintain good functional pavement performance and extend the service life of asphalt pavements, the long-term performance of pavements under maintenance policies needs to be evaluated and favourable options selected based on the condition of the pavement. A major challenge in evaluating maintenance policies is to produce valid treatments for the outcome assessment under the control of uncertainty of vehicle loads and the disturbance of freeze-thaw cycles in the climatic environment. In this study, a novel causal inference approach combining a classical causal structural model and a potential outcome model framework is proposed to appraise the long-term effects of four preventive maintenance treatments for longitudinal cracking over a 5-year period of the upkeep. Three fundamental issues were brought to our attention: 1) detection of causal relationships prior to variables under environmental loading (identification of causal structure);2) obtaining direct causal effects of treatment on outcomes excluding covariates (identification of causal effects);and 3) sensitivity analysis of causal relationships. The results show that the method can accurately evaluate the effect of preventive maintenance treatments and assess the maintenance time to cater well for the functional performance for different preventive maintenance approaches. This framework could help policymakers to develop appropriate maintenance strategies for pavements. Copyright © 2024, The Authors. All rights reserved.

关键词： Sensitivity analysis

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A small-scale experimental study of CO_(2) enhanced injectivity methods of the high-rank coal

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Petroleum Science 2021年第5期18卷 1427-1440页

作者： Qing-He Niu Li-Wen Cao Shu-Xun Sang Wei Wang Wei Yuan Jiang-Fang Chang Xiao-Jun Jia Wei-Min Zheng Zeng-Xue Zhang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang050043China Hebei Technology and Innovation Center on Safe and Efficient Mining of Metal Mines Shijiazhuang050043China School of Resource and Earth Science China University of Mining and TechnologyXuzhou221008China Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization China University of Mining and TechnologyXuzhou221008China Hebei Academy of Emergency Management Shijiazhuang050081China Hebei Iron and Steel Group Mining Co. LtdTangshan063000China Minmetals Mining Holding Co. LtdHefei241000China

The attenuation of CO_(2)injectivity has become the biggest technical barrier for the application of CO_(2)enhanced coalbed methane recovery(CO_(2)-ECBM).Commonly,the intermittent CO_(2)injection,N2 displacing CO_(2)and pre-fracturing are the potential CO_(2)enhanced injectivity methods for coal reservoirs,but their mechanism and effectiveness remain to be *** paper thus conducted small-scale experiments to simulate the working process of these engineering measures by an independently developed experimental *** show that the CO_(2)injectivity of coal is remarkably improved by the intermittent injection mode since the CO_(2)injection time is increased by folds and the loss of reservoir pressure can be complemented in *** N_(2)displacing CO_(2)method promotes the desorption of CO_(2)and reduces the swelling strain,with the result that the permeability of coal is improved by 74.82%and 64.95%compared with the methods of the primary subcritical CO_(2)(Sub CO_(2))and supercritical CO_(2)(Sc CO_(2))***,the permeability reduces again with the secondary CO_(2)*** permeability of the coal sample after pre-fracturing is averagely improved by 1-2 orders of magnitude,the irreversible permeability loss rate,average stress sensitivity coefficient and the permeability loss rate due to adsorption are averagely reduced by 95.885%,61.538%and 96.297%,*** indicates that the permeability of coal after pre-fracturing is no longer sensitive to both the effective stress and Sc CO_(2)adsorption,the injectivity is thus improved and *** CO_(2)enhanced injectivity effects of the intermittent CO_(2)injection,the N_(2)displacing CO_(2)and the pre-fracturing are various,which thus can be selected individually or jointly to improve the CO_(2)injectivity according to the reservoir physical properties and geological *** research deepens the understanding of the functional mechanism of CO_(2)enhanced injectivity method

关键词： Supercritical CO_(2) Permeability Intermittent injection N_(2)displacing CO_(2) Pre-fracturing

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Studies of Turbulent Heat Transfer Properties in Combined Solar Chimneys and Their engineering Applications

SSRN

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SSRN 2023年

作者： Cui, Huimin Han, Mengjiao Zhang, Jitao Han, Zhiming Xu, Feng Liu, Qingkuan State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China School of Physical Science and Engineering Beijing Jiaotong University Beijing100044 China

Solar chimneys can induce natural ventilation through solar radiation. However, sufficient theoretical studies are needed as a basis in order to fully exploit passive design in practical green building design. In this study, the heat transfer properties of turbulent natural convective flows in a combined solar chimney with a thermal flux at the absorption wall are investigated by theoretical analysis and numerical simulations. Two different flow patterns have been discovered, one with an obvious thermal boundary layer flow pattern and the other without, based on the high Rayleigh number. For the flow development in these two flow regimes, the transient scaling analysis is performed separately and the control mechanism for each phase is presented. Scaling correlations of air flow speed, temperature, and mass flow rate have been established to describe the ventilation properties of solar chimneys. The corresponding numerical simulation data is used for scaling verification. Ventilation times are calculated for a solar chimney with aspect ratio A=7.5 to provide a basis for the devise of a solar chimney. © 2023, The Authors. All rights reserved.

关键词： Boundary layers

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A new control strategy for high speed train and its simulation analysis

A new control strategy for high speed train and its simulati...

引用

第八届国际振动工程会议

作者： Yiwei Zhao Shaopu Yang Yongqiang Liu Yingying Liao State Key Laboratory of Mechanical behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Department of Transportation Shijiazhuang Tiedao University Department of Mechanical Engineering Shijiazhuang Tiedao University Department of Civil Engineering Shijiazhuang Tiedao University

For a long time, the dynamic performance of high-speed train has been studied by many experts. And it will continue to be studied in the future with the rapid development of high-speed trains. The ride comfort and safety of trains which is the part of the dynamic performance is studied in this paper through applying the control method to the secondary lateral dampers and yaw dampers. Firstly, a train model is built by multi-body dynamics software UM. Then the co-simulation model is built in Simulink for the further study. The second, the multi-objective optimization for the damper damping coefficient of the secondary lateral dampers and yaw dampers is carried out in a straight track. The optimal damping coefficient that can improve the ride comfort and safety simultaneously is obtained. The objectives of optimization are the lateral acceleration and derailment coefficient. Similarly, the multi-objective optimization for the damping coefficient of the two kind of dampers is carried out in a curve track. The optimal damping coefficient is obtained. In order to keep the ride comfort and safety of the train, no matter in a straight track or in a curve track, the semi-active control method is proposed to adjust the damping coefficient. In this way, the damping coefficients of the two kinds of shock absorbers are always ***, the train model is simulated and *** results show that the control method that the two kinds of shock absorbers are controlled at the same time can significantly improve the ride comfort and safety of the train whether it's running in a straight track or a curve track. In other words,multi-point control can improve the train dynamic performance comprehensively.

关键词： high-speed train co-simulation semi-active ride comfort safety

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Erratum: ‘Scattering of SH Waves Around Circular Canyon in Inhomogeneous Wedge Space’

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Geophysical Journal International 2021年第1期226卷 345-350页

作者： Zailin Yang Xinzhu Li Yunqiu Song Guanxixi Jiang Menghan Sun Xueqian Fang College of Aerospace and Civil Engineering Harbin Engineering University Harbin China Key Laboratory of Advanced Material of Ship and Mechanics Ministry of Industry and Information Technology Harbin Engineering University Harbin China sunmenghan163@*** State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

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The Effects of Row Spacing and Ground Clearance On the Wind Load of Photovoltaic (Pv) Arrays

SSRN

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SSRN 2023年

作者： Xu, Ang Ma, Wenyong Yuan, Huanxin Lu, Lihe 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 Shijiazhuang Hebei050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Hebei050043 China School of Civil Engineering Wuhan University Wuhan430072 China Inner Mongolia Electric Power Survey & Design Istitute Co. Ltd. Huhehot Inner Mongolia 010011 China

Row spacing and ground clearance have a significant effect on the wind load of a photovoltaic (PV) array. Based on wind tunnel tests and numerical simulations with the self-sustainable equilibrium atmospheric boundary layer, the influences of row spacing and ground clearance on the wind load of PV arrays are analysed, and the mechanism of the wind-induced interference effect is determined by flow field analysis. The results show that the ground clearance affects the wind load distribution on the PV module, and this effect has an inconsiderable impact on the net wind pressure on the PV modules. The effect of row spacing on the wind load of PV arrays is more significant, and this effect is mainly manifested in the shielding effect. The tilt angle is the main factor that affects the size of the vortex scale which significantly influences the wind load. The ground clearance, row spacing and tilt angle all affect the torque coefficient on the PV module. The larger the ground clearance is, the larger the torque coefficient. Finally, the wind load coefficients and reduction factors are presented as a recommendation for wind resistance design of PV arrays. © 2023, The Authors. All rights reserved.

关键词： Atmospheric boundary layer

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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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