检索结果-内蒙古大学图书馆

SSRN 2022年

作者： Cheng, Shu-Liang Yang, Hong-Yun Yan, Qun Wang, Bin Sun, Yong-Tao Xin, Ya-Jun Ding, Qian Yan, Hao Wang, Liang Key Laboratory of Mechanical Reliability for Heavy Equipment and Large Structure of Hebei Province Yanshan University Qinhuangdao China Tianjin Key Laboratory of Soft Soils and Engineering Environment Tianjin Chengjian University Tianjin China Department of Mechanics Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin University Tianjin China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China Key Laboratory of Aeroacoustics and Dynamics Aircraft Strength Research Institute Xi’an China Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province Yanshan University Qinhuangdao China

In this paper, a new type of single-phase metamaterial is proposed. Based on the finite element method, the band gap characteristics of the structures with different branches are comprehensively analyzed, and the existence of the band gap is further verified by the frequency response transmission spectrum. Then, the propagation characteristics of elastic waves of different frequencies in different combinations of structures are investigated respectively. The results show that the proposed single-phase metamaterial structure has an excellent band gap range, and under the action of relatively low-frequency elastic waves, the wave propagation in the structure has a certain direction and regionality, while the elastic waves at higher frequencies are applied, the propagation direction of the wave tends to propagate in all directions. This paper provides a new idea for studying the structural design of metamaterials with specific wave propagation directions. © 2022, The Authors. All rights reserved.

关键词： Energy gap

来源：评论

学校读者我要写书评

暂无评论

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

SSRN

引用

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

来源：评论

学校读者我要写书评

暂无评论

Simulations on Pressure Characteristics of Low-Flow Rate Water Circulating System Based on Porous Media Model 1

引用

11th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC 2019

作者： Xue, Yu Zhao, Wenxuan Ye, Wei Wu, Chao Zhang, Xu School of Mechanical Engineering Tongji University Shanghai201804 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University 1239 Siping Road Shanghai200092 China

ISBN: (数字)9789811395284

ISBN: (纸本)9789811395277

A spherical experimental device is placed in an underground cylindrical laboratory hall, and the surface is covered with ~17,510 photomultiplier tubes (PMTs) for detecting radiation signals. Since the device is placed underground for a long time, an effective water circulation is required to remove radon and algae to ensure stable operation. In this paper, the pressure distribution characteristics of water in the PMT region are studied. The PMT areas of the device are simplified into a porous media. Two models, i.e., a vertical-flow and a horizontal-flow model, were established to obtain the coefficient of resistance using CFD. In addition, the relationship between the pressure difference and the water entry parameters in the porous media is also studied. The results show that the resistance coefficients of single-layer PMT and two-layer PMT are similar in the vertical direction. However, the resistance coefficient of two-layer PMT in the horizontal direction is smaller than that of the single-layer PMT. Another simplified 2D model was also proposed to further study the effect of the simplified porous media on the overall flow. Overall, when the water inlet velocity is smaller, and the angle of inclination of the inlet is larger, the fluid is more likely to pass through the PMT areas, and the pressure distribution in the PMT areas can be more uniform. © 2020, Springer Nature Singapore Pte Ltd.

关键词： Porous materials

来源：评论

学校读者我要写书评

暂无评论

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

SSRN

引用

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

来源：评论

学校读者我要写书评

暂无评论

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

来源：评论

学校读者我要写书评

暂无评论

Stability study of electromagnetic SD oscillator vibration isolation system considering nonlinear characteristics of electromagnetic force under state feedback control

引用

Chaos, Solitons and Fractals 2025年 199卷

作者： Wang, Meiqi Zu, Qian Wang, Ruichen Qin, Chengwei Liu, Pengfei School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Hebei Key Laboratory of Mechanical Power and Transmission Control Shijiazhuang Tiedao University Shijiazhuang050043 China CRRC Tangshan Co. Ltd Tangshan064000 China

To enhance the robustness of SD oscillator system, an electromagnet with state feedback control is introduced above the oscillator, considering the nonlinear characteristics of the electromagnetic force. Initially, the system's steady-state amplitude-frequency response, phase-frequency response, and backbone curve are determined using the averaging method. These results are compared with the traditional SD oscillator, analyzing the influence of state feedback parameter on vibration isolation effectiveness and acceleration transmissibility. Subsequently, differences in bifurcation diagrams between the conventional SD oscillator and the electromagnetic SD oscillator are examined, focusing on how parameters affect the system's dynamic bifurcation characteristics. Finally, employing the cell mapping method, the global bifurcation characteristics are analyzed, investigating how parameters influence the number of attractors and the area of their attraction domains. The research indicates that the system exhibits rich nonlinear characteristics, and that appropriate selection of state feedback parameters can effectively suppress chaos and bifurcations induced by external excitation, thereby enhancing the system's stability and vibration isolation performance. © 2025 Elsevier Ltd

关键词： State feedback

来源：评论

学校读者我要写书评

暂无评论

Research on Brake Failure control of Heavy Commercial Vehicles Based on Turning Conditions

Research on Brake Failure Control of Heavy Commercial Vehicl...

引用

Conference on Vehicle control and Intelligence (CVCI)

作者： Yongjie Lu Fahui Wang Guangfeng Zhang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (数字)9781728184975

ISBN: (纸本)9781728184982

With the rapid rise of the transportation industry, commercial vehicles as an important means of transportation, its safety and stability are paid more and more attention. In order to improve the safety performance of heavy commercial vehicles when braking failure occurs under turning conditions. Based on the vehicle dynamics characteristics, this paper designed the stability control strategy in the case of brake failure in the above conditions, designed a fuzzy PID controller based on yurch angular velocity control, carried out the Trucksim-Simulink joint simulation and hardware in the loop experiment to jointly verify the control effect of the brake. The results show that the influence of vehicle brake failure on vehicle driving stability is reduced, the performance of vehicle brake under long and downhill conditions and turning conditions is improved, and the safety stability of vehicle brake failure in hardware loop is improved, which meets the requirements of national standards for vehicle braking.

关键词： Stability criteria Turning Hardware Safety Brakes Acceleration Standards

来源：评论

学校读者我要写书评

暂无评论

Effects of microstructural heterogeneity on fatigue properties of cast aluminum alloys

引用

Journal of Central South University 2020年第3期27卷 674-697页

作者： JIAO Yi-nan ZHANG Yi-fan MA Shi-qing SANG De-li ZHANG Yang ZHAO Jin-jin WU Sheng-chuan LIU Yong-qiang YANG Shao-pu School of Materials Science and Engineering Hebei Key Laboratory for Mechanics of Intelligent Materials and StructuresShijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,*** subjected to mechanical cyclic load during *** accurate fatigue life prediction of these alloys is essential for normal operation as fatigue cracks initiated during operation induce the lubrication oil leak and serious safety *** heterogeneity,including shrinkage/gaspores and secondary phase particles,is the most detrimental factor that affects fatigue life of cast Al *** approximate fatigue life cycles could be estimated based on the size distribution and locations of shrinkage pores/*** relationship between crack population and stress was reported by statistical distributions and the cumulative probability for cast Al alloys fail at a certain stress could be predicted by combination of Paris law and pore size *** depth was found to dominate the stress field around the pore on the surface and the maximum stress increases sharply when the pore intercepted with the surface at its *** microstructure of cast Al alloys usually is composed of primary Al dendrites,eutectic silicon,Fe-rich particles and other intermetallic particles are dependent upon alloy composition and heat *** coalescence of microcracks initiated from the fractured secondary phases was clearly found and can accelerate the initiation and propagation of the fatigue cracks.A link between defect features and the fatigue strength needs to be established through a good understanding of the fatigue damage mechanisms associated with the microstructural features under specific loading *** paper reviews the influences of shrinkage/gaspores and secondary phase particles,formed during casting process,on the fatigue life of Al-Si-Mg cast Al alloys.

关键词： cast aluminum alloys fatigue microstructural heterogeneous shrinkage/gas pore secondary phase particles

来源：评论

学校读者我要写书评

暂无评论

An Improved Autogram and its Application in Bearing Fault Diagnosis

An Improved Autogram and its Application in Bearing Fault Di...

引用

Prognostics and System Health Management (PHM-Jinan), International Conference on

作者： Wenpeng Liu Shaopu Yang Qiang Li Yongqiang Liu School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (数字)9781728151816

ISBN: (纸本)9781728151823

Envelope analysis is one of the most advantageous methods in rolling element bearing (REB) diagnosis, but the determination of the informative frequency band (IFB) is always a huge challenge. In order to reduce the influence of discrete frequency components and strong background noise to choose IFB, a new improved Autogram is provided. Firstly, the Cepstrum pre-whitening (CPW) is taken as a preprocessing method to reduce the interference from discrete frequency components in the signal. Then, the Autogram is used to decompose the pre-whitening signal and the optimal IFB is selected for a further demodulation. The simulated signals and a set of experiment signals are taken to verify its validity. The results indicates that this method can successfully address the interference generated by discrete frequency and strong background noise, and effectively extract the weak fault features of bearing.

关键词： Interference Time-frequency analysis Coplanar waveguides Noise measurement Vibrations Cepstrum Gears

来源：评论

学校读者我要写书评

暂无评论

Effects and mechanisms of the main longitudinal beam shape on vortex-induced vibrations of Π-shaped composite girders

引用

structures 2025年 78卷

作者： Li, Kaiwen Sun, Yifei Liu, Qingkuan Wang, Yangxue Wang, Qingcai Wang, Binxuan School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Key Laboratory of Roads and Railway Engineering Safety Control Ministry of Education Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China Research Center for Wind Engineering and Engineering Vibration Guangzhou University Guangzhou510006 China

As a typical blunt body cross-section, Π-shaped composite girders are notably susceptible to vortex-induced vibrations (VIVs). Therefore, it is crucial to investigate their VIV characteristics and develop corresponding aerodynamic countermeasures. In the present study, synchronous pressure and vibration measurements, combined with computational fluid dynamics (CFD) simulations, were conducted for various Π-shaped composite girder models with different main longitudinal beam shapes. The effects of the main longitudinal beam height (h), bottom plate width (b), and bottom plate inclination angle (β) on the vertical VIV were systematically investigated. The underlying mechanisms of VIV for these parameters were discussed by analyzing the time-frequency characteristics of aerodynamic forces, the relationship between local lift forces and vortex-excited forces (VEFs), and flow field characteristics. The results indicate that reducing h, increasing b, or setting β to 20° can suppress vertical VIV, but the suppressive effect varies and is related to the wind attack angle. From the perspective of the flow field, the formation and movement of the large separation vortices at the leading edge of the girder are responsible for the observed vertical VIVs. The aforementioned parameter adjustments that exhibit an excellent VIV suppression effect can reduce the size and suppress the development of the leading-edge vortices, thereby improving the stability of the flow field. From the perspective of aerodynamic force characteristics, these adjustments can reduce the RMS value of the surface pressure coefficient. They can also shift the dominant frequency of the pressure spectrum away from the vibration frequency, weaken the dominant role of the vibration frequency in the overall lift, and greatly reduce the contribution of local lift to the overall vortex-excited forces (VEFs). As a result, VIV is suppressed. © 2025

关键词： Flow fields

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：