Papers by Keyword: Numerical Analysis

Abstract: Combined with the project of an open cut metro tunnel passing through a viaduct, three- dimensional finite element method is applied to study the lateral deformation law of viaduct pile foundations induced by adjacent excavation in the pile foundations reinforcement and un-reinforcement conditions. The results show that the lateral deformation of pile foundations increases with the increasing of excavation depth. The closer distance and the larger deformation, the influence of pile foundations on excavation will be more obvious. The pile foundations deformation is significantly reduced when taking protection measures such as adding new piles, expanding the pile cap and strengthening stratum. Compared with the maximum deformation of the un-reinforcement condition, the reinforcement condition is only 27% to 30%, and the reinforcement measure is remarkably effective. In addition, the length of the piles, the depth of foundation pit, as well as the relative positions of walls and piles have significant influences on piles deformation forms, and it should be taken into account in the design and construction of foundation pit.

Abstract: The FLAC-3D software was used to study the surrounding rock displacement and the side abutment pressure distribution laws about roadway in thick coal seam. Based on this model, through change the mining height, working face length and mining depth, the differences of roadway underground pressure characteristics were analyzed between thick coal seam working face and normal working face. The results indicate that: ①the displacement of roadway surrounding rock increases with the increase of mining depth and mining height, the closer to the coal wall the larger of the increase range of roadway displacement. ②the peak of side abutment pressure increases with the increase of mining depth and mining height, the peak district of the stress will move toward the inner department of rock body. ③ the effect of working face length on the roadway displacement and the side abutment pressure is very feeble.

Abstract: This essay introduced that shape memory alloy in martensite-austenite coexisting was use to control the structural vibration. The proportion of martensite and austenite in shape memory alloy was selected which could realize the two basic characteristics of shape memory alloy. Based on Liang model, the mechanical model of shape memory alloy was established. The computer simulation analysis of the structure was achieved by using Matlab, and the result of numerical analysis proved that shape memory alloy in martensite-austenite coexisting could effect structural vibration control.

Abstract: In order to solve the weighing problem of a type of incubator shakers, a new weighing method, combined with numerical analysis and experimental verification, is proposed. The numerical analysis based on the software of ANSYS Workbench indicates that the sum of the two-point strain in the mechanism is found to be constant and there is a fine linearity relationship between the sum of the two-point strain and the weight of load, so as to offer a measurement method for indirect measurement of the loading weight and this measuring method has been verified by experiment.

Abstract: This article states seal clearance and fluid leakage.By means of pressure distribution calculation and theoretical analysis, theoretically it establishs the mathematical model of the leakage with liquid material, the sealing structure and the fuel tank between the internal and external pressure.The whole processes on Matlab platform meet the complex engineering requirements,so the calculation process is simple and convenient. By calculating the results should be very intuitive, it closes to the sealing gap and leakage distribution curve. Thus, it is sure sealing clearance is the first element in the ultra-high pressure seal system.

Abstract: Detailed prediction of steam flow field and heat transfer process is significant for the condensers. The flow and heat transfer performance of the condenser of 600MW power unit is numerical simulated. A model of porous media with distributed resistance and mass sink is used to simulate the function of the tube bundle. The equations including the continuous, momentum and air concentration are numerically solved using the finite control-volume integration method and SIMPLE algorithm. The distribution of steam velocity, pressure, heat transfer coefficient and air concentration are obtained and analyzed. On the basis of results, the condenser is evaluated.

Abstract: This study deals with the seismic assessment and retrofitting of existing non-ductile R/C structures and the issue of selecting effective strengthening solutions is addressed. A displacement based procedure using nonlinear static pushover analyses is adopted in order to assess the main characteristics of the original structure and to select valuable retrofitting strategies. The procedure is applied to a four-storey R/C frame tested at the JRC ELSA Laboratory some years ago. The R/C frame was designed for gravity loads without specific earthquake-resistant provisions. Accurate numerical models are developed to reproduce the seismic response of the R/C frame in both the original and retrofitted configurations. The effectiveness of two strengthening techniques is examined. First, a retrofitting intervention is carried out by adding a concrete shear wall to the short bay of the frame. This solution is efficient in controlling global lateral drift and thus reducing damage in structural members. Then, a retrofitting solution involving the introduction of eccentric steel bracing is investigated in order to reduce the displacement demand and to increase the energy dissipation capacity of the frame. Nonlinear dynamic analyses are performed to assess and compare the seismic response of the frame in the original and retrofitted configurations.

Abstract: In this study, a methane/oxygen-enriched air counterflow diffusion flame was analyzed numerically using detailed chemical kinetics, on the condition that the oxygen mass fraction in the oxidizer stream varied from 21% to 99%. The obtained results show that as the oxygen concentration in air increases, the maximum temperature increases; the region of combustion reaction is gradually divided into two parts, and the total NO production rate and especially the thermal NO production rate increase greatly. With consideration of the possibility of gas recirculation to minimize NO_X in the industrial combustor, the usefulness of NOX reduction in combustion was analyzed numerically when the methane stream was diluted with the inert gases N2 or CO2. The obtained results show that the flame structure and dominant mechanism of NO formation change greatly with the concentration of diluents in fuel; the emission index of NO decreases gradually when the concentration of diluent CO2 increases.

Abstract: As the bridge design theory and the construction level improving, the requirements on bridge's appearance and coordination of the landscape around have also became higher and higher in the scenic area. In this paper, we conducted a numerical analysis on structure stress of Wudu bridge at Laibao Road, in Fang Shan district , Beijing, located in the Wu du scenic spot. And we seek to provide the necessary theoretical basis for the bridge design and model selection.

Abstract: Combined composite foundation has been widely used in actual projects, but its working behaviors need to be studied further. By establishing finite element model, the effect of the core pile was researched. Analysis shows that, the diameter and the length of core pile affect the bearing capacity of combined composite foundation significantly. There is an optimal value of the length and the diameter of core pile, which can make the foundation generate maximum carrying capacity. With the increase of core pile length, the depth of neutral point increased.