Time filter

Source Type

Chongqing, China

Wang Z.A.,Southwest Jiaotong University | Zhou Z.R.,Southwest Jiaotong University | Chen G.X.,leu
Industrial Lubrication and Tribology

Purpose - The paper aims to study comparatively the fretting behavior in gross slip regime of fretting both under grease lubrication and dry condition and to investigate the mechanism of palliation of fretting wear with grease lubrication. Design/methodology/approach - All fretting tests were carried out on high-temperature fretting devices with standard GCr15 bearing steel ball against 45 steel flat and against GCr15 bearing steel flat contact pairs. The wear scar was examined by optical microscope, surface profiler and the confocal laser scanning microscope as well as energy dispersive X-ray spectroscopy. Findings - Compared with dry condition, the coefficient of friction and wear are decreased drastically and wear occurs mainly at the early stage of fretting under grease lubrication. The palliation effect of grease lubrication is closely associated with the amount of oil separated from the grease, the low-oxidation corrosion and high-hardness white layer. However, the bubbles which expelled from the contact edges have little influence on fretting wear. Research limitations/implications - The tested greases do not contain any additives for preventing possible misinterpretations of the results, but it is necessary to investigate the influence of different lubricant additives added to grease on friction and wear at different fretting conditions. Practical implications - The research reveals that the palliation effect of grease lubrication on fretting wear is related closely to the amount of oil separated from the grease. The bigger penetration and more susceptible greases, which are easier to separate from the base oil, should be taken into account for palliation of fretting wear. Originality/value - The presented results help to understand the palliation mechanism of grease lubrication and could be useful for designers of engineering assembly for which fretting wear is an issue. Copyright © 2011 Emerald Group Publishing Limited. All rights reserved. Source

Chen Z.-H.,leu
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

Thorough researches on unsaturated soils and special soils including fill, collapsible loess, expansive soil, bentonite and sandy clay, are carried out, and a series of novel results are obtained. A lot of instruments and equipments suitable for unsaturated soils and special soils, such as oedometer, direct shear apparatus, gas permeation device, multifunction triaxial apparatus and temperature-controlled triaxial apparatus as well as CT-triaxial apparatus, are successfully developed. Important mechanical properties and laws of water flow, air flow, deformation, strength, yield, moisture and meso-structure of unsaturated soils and special soils are revealed. An axiomatics theoretical system of geomechanics and the stress state variables of unsaturated soils are established. The formulae for effective stresses isotropic unsaturated soils and anisotropic porous media are proposed. The constitutive hierarchy including nonlinear model, elasto-plastic model, coupled temperature-mechanical model and meso-structure damage model as well as the general model for soil-water characteristics curve are established. The 3-D consolidation theory based on the theory of mixture and the hierarchy of consolidation model are created, the relevant software to solve 2-D consolidation problems is programmed independently, and the analytical solutions to 1-D problems and the numerical solutions to 2-D problems are obtained. Many difficult problems such as deformation and stability of dams and embankments are solved using the above achievements. It is indicated that the proposed theories can be adopted to guide engineering practices and to be as the theoretical basis for engineering decision. Source

Sun G.,Wuhan University | Sun G.,Hei Longjiang Institute of Geological Survey | Sun G.,Northeast Petroleum University | Li Z.,Institute of Geochemistry Chinese Academy of science | And 4 more authors.
Atmospheric Environment

Mercury (Hg) contamination in urban area is a hot issue in environmental research. In this study, the distribution, sources and health risk of Hg in dust from 69 kindergartens in Wuhan, China, were investigated. In comparison with most other cities, the concentrations of total mercury (THg) and methylmercury (MeHg) were significantly elevated, ranging from 0.15 to 10.59mgkg-1 and from 0.64 to 3.88μgkg-1, respectively. Among the five different urban areas, the educational area had the highest concentrations of THg and MeHg. The GIS mapping was used to identify the hot-spot areas and assess the potential pollution sources of Hg. The emissions of coal-power plants and coking plants were the main sources of THg in the dust, whereas the contributions of municipal solid waste (MSW) landfills and iron and steel smelting related industries were not significant. However, the emission of MSW landfills was considered to be an important source of MeHg in the studied area. The result of health risk assessment indicated that there was a high adverse health effect of the kindergarten dust in terms of Hg contamination on the children living in the educational area (Hazard index (HI)=6.89). © 2013 Elsevier Ltd. Source

Zhou J.,leu | Jiao G.,leu | Zhang X.,China Huayi Broadcasting Corporation
Energy Education Science and Technology Part A: Energy Science and Research

Aimed at the phenomenon of the leakage from the hole of high pressure buried gas pipeline,the simulation of buried gas pipeline pinhole leakage heat absorption rate and stationary and transient temperature field is simulated. Using the finite element analysis software ANSYS Workbench 14.0 to simulation verification the special frozen soil caused by gas release. The results show that the natural gas pipeline pinhole leakage can lead to frozen soil in a few times. At beginning the frozen soil’s curtain increase rapidly, with the time going the curtain increase slowly until transient. © Sila Science. All rights reserved. Source

Tan W.-P.,leu | Tan W.-P.,Chongqing Geological Hazard Control Engineering Technology Research Center | Zheng Y.-R.,leu | Zheng Y.-R.,Chongqing Geological Hazard Control Engineering Technology Research Center | Wang K.,HIGH-TECH
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

Creep property of rock and soil is important for landslide deformation and stable state. And it is necessary to be considered for analyzing stable state and prediction of landslides by displacement monitoring resources. With the landslide project which lies on Yunyang County in Chongqing City of China, the strength reduce technology considering creep properties is employed to study landslide deformation mechanism through analysis on macro phenomenon observation, monitoring displacement trend and numeral computing results. The final research shows that through comparing the monitoring displacement curves with the calculated displacement curves, the quantitative determination of the landslide stable state combined with qualitative experience can make accurate landslide prediction, and it can provide important reference for engineering decision-making. Source

Discover hidden collaborations