Research on the longitudinal stress distribution in steel box girder with large cantilever

Yu Hong,ShengYu LI,Yining WU,Dailing XU,Qianhui Pu 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.5

There are numerous structural details (Longitudinal beam, web plate, U-ribs and I-ribs) in the top and bottom plates of steel box girders, which have significant influences on the longitudinal stress (normal stress) distribution. Clarifying the influence of these structural details on the normal stress distribution is important. In this paper, the ultra-wide steel box girder with large cantilevers of the Jinhai Bridge in China, which is the widest cable-stayed bridge in the world, has been analyzed. A 1:4.5 scale laboratory model of the steel box girder has been manufactured, and the influence of structural details on the normal stress distribution in the top and bottom plates for four different load cases has been analyzed in detail. Furthermore, a threedimensional finite element model has been established to further investigate the influence regularity of structural details on the normal stress. The experimental and finite element analysis (FEA) results have shown that different structural details of the top and bottom plates have varying effects on the normal stress distribution. Notably, the U-ribs and I-ribs of the top and bottom plates introduce periodicity to the normal stress distribution. The period of the influence of U-ribs on the normal stress distribution is the sum of the single U-rib width and the U-rib spacing, and that of the influence of I-ribs on the normal stress distribution is equal to the spacing of the I-ribs. Furthermore, the same structural details but located at different positions, will have a different effect on the normal stress distribution.

Damage detection of subway tunnel lining through statistical pattern recognition

Yu, Hong,Zhu, Hong P.,Weng, Shun,Gao, Fei,Luo, Hui,Ai, De M. Techno-Press 2018 Structural monitoring and maintenance Vol.5 No.2

Subway tunnel structure has been rapidly developed in many cities for its strong transport capacity. The model-based damage detection of subway tunnel structure is usually difficult due to the complex modeling of soil-structure interaction, the indetermination of boundary and so on. This paper proposes a new data-based method for the damage detection of subway tunnel structure. The root mean square acceleration and cross correlation function are used to derive a statistical pattern recognition algorithm for damage detection. A damage sensitive feature is proposed based on the root mean square deviations of the cross correlation functions. X-bar control charts are utilized to monitor the variation of the damage sensitive features before and after damage. The proposed algorithm is validated by the experiment of a full-scale two-rings subway tunnel lining, and damages are simulated by loosening the connection bolts of the rings. The results verify that root mean square deviation is sensitive to bolt loosening in the tunnel lining and X-bar control charts are feasible to be used in damage detection. The proposed data-based damage detection method is applicable to the online structural health monitoring system of subway tunnel lining.

Serviceability assessment of subway induced vibration of a frame structure using FEM

Yuhong Ling,Jingxin Gu,T.Y. Yang,Rui Liu,Yeming Huang 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.2

It is necessary to predict subway induced vibration if a new subway is to be built. To obtain the vibration responsereliably, a three-dimensional (3D) FEM model, consisting of the tunnel, the soil, the subway load and the building above, isestablished in MIDAS GTS NX. For this study, it is a six-story frame structure built above line 3 of Guangzhou metro. The entiremodeling process is described in detail, including the simplification of the carriage load and the determination of model parameters. Vibration measurements have been performed on the site of the building and the model is verified with the collected data. Thepredicted and measured vibration response are used together to assess vibration level due to the subway traffic in the building. TheNo.1 building can meet work and residence comfort requirement. This study demonstrates the applicability of the numerical traintunnel-soil-structure model for the serviceability assessment of subway induced vibration and aims to provide practical referencesfor engineering applications.

Behaviour and Modeling of the Bearing Capacity of Shear Stud Connectors

Yuhong Ling,Zhaoyi Zheng,T.Y. Yang,Hongwei Ma 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2

The bearing capacity of shear stud connectors from the simplifi ed design equations in diff erent building codes tends to be underestimated because of a relatively large safety factor. Finite element analysis using ABAQUS was carried out to simulate the force–deformation response of shear stud. The fi nite element model was verifi ed by using push-out tests, and detailed parametric numerical studies were conducted to investigate the force–deformation response of diff erent shear stud confi gurations. A new design equation was derived from linear regression based on the results of the parametric studies. The presented equation shows better agreement with the experimental data. Detailed comparison between the proposed equation and existing design equation in China code for shear stud strength was carried out. The results show signifi cant reduction in the construction cost when the new equation is used.

Wireless charging system for unmanned aerial vehicles using lightweight and compact receiver modules

Yuhong Tian,Zhenjie Li,Hao Liu,Yiqi Liu,Mingfei Ban,Junyuan Zheng 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.4

This paper proposes a wireless charging system (WCS) for unmanned aerial vehicles (UAVs) that features a lightweight andcompact receiver module and constant current/constant voltage (CC/CV) charging. Optimizing the LCC-none compensation topology reduces the weight and volume of the receiver module mainly by avoiding the secondary-side resonant capacitors. In addition, high system performance similar to that of the LCC-S compensation topology is achieved. A magnetic coupler with dual power transfer channels is designed using the specific structure of the UAV. The reasonable charging zone is determined by optimizing the magnetic coupler parameters. Besides, a primary-side PI-controlled Buck converter is used to realize CC/CV charging with a high system efficiency under a suitable misalignment range to avoid the secondary-side circuit and control complexity. Finally, both simulation and experimental results verify the feasibility of the designed WCS. The total weight of the receiver coil is only 54 g. During 5 A CC charging, the tested maximum output power and system efficiency values are 90 W and 87.2%, respectively.

Forming Limit and Mechanical Properties of 2024-O Aluminum Alloy Under Electromagnetic Forming

Yuhong Lin,Xiaohui Cui,Kanghua Chen,Ang Xiao,Ziqin Yan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.10

The effect of electromagnetic forming (EMF) on the forming limit and properties of 2024-O aluminum alloy is studied in thispaper. This was done to address the important problems related to the poor forming limit of aluminum alloy when conventionalstamping is used. The evolution of the microstructure of the alloy during quasi-static stamping (QS) and the dynamicdeformation is analyzed. This was done using mechanical testing, texture analysis, scanning electron microscopy (SEM),fracture analysis, and transmission electron microscopy (TEM). Compared with QS, the forming limit for EMF increases by36.9%. For the same deformation height with 17.6mm, the maximum degree of thickness thinning of the sample for EMF is4.7%, and 6.4% for QS. The thickness distribution of the EMF sample is more uniform than for the QS sample. Numericalsimulation shows the maximum principal stresses at different points were almost same with each other after EMF, whichleads to uniformity plastic deformation of samples. In addition, the grain size of the material decreases, the proportion ofsmall-angle grains increases, and the copper texture increases after EMF. When EMF is used, the dislocation density of thesample is significantly higher than for QS and the dislocation distribution is more uniform. The temperature rise is small,which is not a significant reason for dislocation dispersed in EMF.

Feasibility of ultrasonic vibration assisted grinding for carbon fiber reinforced polymer with monolayer brazed grinding toolss

Yuhong Liang,Yan Chen,Binbin Chen,Baopeng Fan,Chaoren Yan,Yucan Fu 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.7

Ultrasonic vibration assisted grinding (UVAG) is an effective method for edge trimming to improve the mechanical integrity of carbon fiber reinforced polymer (CFRP). However, due to the high heat resistance, abrasiveness and powdery chip of CFRP, serious tool clogging, rapid tool wear and poor surface are still considerable problems to the industry. In this paper, monolayer brazed diamond grinding tools with defined grain distribution are designed in order to solve the above problems. The maximum undeformed chip thickness based on UVAG was analyzed. A mathematical grinding force model was established based on monolayer brazed diamond tools. The UVAG experiments using different grain inter-row spacing diamond tools were carried out. The grinding force and surface morphology were investigated and compared. It was found that the predicted grinding force values were consistent with the experimental results. Additionally, the force was strongly related to the grain inter-row spacing. When employing the tool with the grain inter-row spacing of 1.2 mm, the grinding force was highest and the roughness of the surface was better due to more active grits and interaction-overlap areas.

Fixed Charge Transportation Problem and Its Uncertain Programming Model

Yuhong Sheng,Kai Yao 대한산업공학회 2012 Industrial Engineeering & Management Systems Vol.11 No.2

In this paper, we study the fixed charge transportation problem with uncertain variables. The fixed charge transportation problem has two kinds of costs: direct cost and fixed charge. The direct cost is the cost associated with each source-destination pair, and the fixed charge occurs when the transportation activity takes place in the corresponding source-destination pair. The uncertain fixed charge transportation problem is modeled on the basis of uncertainty theory. According to inverse uncertainty distribution, the model can be transformed into a deterministic form. Finally, in order to solve the uncertain fixed charge transportation problem, a numerical example is given to show the application of the model and algorithm.

Nanoscale Interface Control for High-Performance Li-Ion Batteries

Yuhong Oh,Seunghoon Nam,Sungun Wi,Saeromi Hong,Byungwoo Park 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.2

Li-ion batteries have attracted great interest for the past decades, and now are one of the most important power sources for portable electronic devices, store electricity, hybrid electric vehicles (HEV), etc. However,Li-ion-battery technologies still have several problems related to the electrochemical performance (cycle-life performance and power density) or safety of the active electrode materials. There have been numerous break-through challenges to overcome these problems by extensive research. Among the various methods to improve the battery’s electrochemical properties, nanoscale coating on active materials and control of the nanostructured morphology were proven as effective approaches over the last decade. In this review paper, enhanced elec-trochemical properties of the cathode and anode materials via nanoscale interface modification and the respective enhancing mechanisms will be discussed.

Preparation and Super-Water-Absorbency of Poly(sodium acrylate-co-acrylamide-co-2-hydroxyethyl acrylate)

Yuhong Zhang,Min Deng,Peixin He 한국고분자학회 2006 폴리머 Vol.30 No.4