Applied Mechanics and Materials Vols. 602-605

Abstract: The turbulent flow inside contra-rotating disk cavity was numerically studied based on the finite volume method. The flow structure and its transition characteristics inside a contra-rotating were studied. The flow structure varies with the angular velocity ratio Γ of the slower disk to that of the faster one. For Γ=-1, the Stewartson-type flow occurs throughout the domain. For Γ=0, the Batchelor-type flow occurs throughout the flow region. The stagnation streamlines originating from the stagnation point are formed for-1<Γ<0, and batchelor-type flow occurs radially outward of the stagnation point with Stewartson-type flow radially inward. The stagnation point moves radially outward as Γ is reduced.

Abstract: To assess piston’s thermal loads, the direct and effective method is to calculate piston’s temperature distribution. A key point in calculating the temperature field of a piston is the determination of heat transfer boundary conditions of each side, especially the gas side. The thermal boundaries of a piston consist of the piston top side (combustion side), the crevice surfaces, the piston ring land and skirt outside surface, piston underside and pin hole side.The calculating methods for the heat transfer boundary conditions of engine piston are studied according to the theoretical analysis of heat transfer of engine piston, which can be taken as a reference for providing precise boundary conditions for the research on piston’s temperature field.

Abstract: Because the anisotropy of shale formation should result in that wellbore deviations is unpredictable, the bit-rock interaction should be fully lucubrated in order to eliminate this problem. The impact of shale rock anisotropy and the cutting velocity on the load of PDC cutter wasn’t considered by the existing cutter-rock interaction models. On the basis of experiments of cutting shale with PDC cutter, using the stress tensor analysis theory, the relationship between the shale rock anisotropy and the cutter’s force is proposed in this paper. A new cutter-rock interaction model was established, and then a new bit-rock interaction model was set up. That applying these models to the ROP prediction of directional PDC bit can improve forecast accuracy is found.

Abstract: s: Temperature, seepage and deformation are the important parts of the engineering geological mechanics both in water conservancy and hydropower engineering since there are highly nonlinear complex coupling effect between each other. In this paper, the earth and rock mass are classified as continuous porous media. The thermal constitutive relation of porous media and motion regularity of pore fluid are deduced from the basic theory of solid mechanics, hydraulics, and thermodynamics. Based on momentum, mass and energy conservation equations, the multi-field controlling equations of unsaturated porous media are given, in which the unknown variables include displacements, pore liquid pressure, pore gas pressure, temperature, and porosity.

Abstract: Health assessment of the girder is crucial to an overhead traveling crane. This paper presents an intelligent damage identification method for the girder based on stiffness variation index (SVI) and least squares support vector machine (LSSVM). In the method, the SVI indicators, which have high resolution to environmental noise, serve as the damage feature to detect damage locations. Moreover, the SVI indicators are input to the LSSVM classifier for identifying the actual damage level of the girder. A case study on girder damage identification demonstrates that the method could determine the actual conditions of the girder structure accurately.

Abstract: This paper mainly introduces the related theory and method of cylindrical gas film seal, the structure and principle of the cylindrical gas film seal, and solving the mathematical model, introduces several methods commonly used for solving the gas film pressure, and compare these methods, get the applicable conditions and calculation error of these methods.

Abstract: The analysis of slamming effect has been mainly discussed about the local strength assessment and the global longitudinal strength assessment under slamming loads. The former is to forecast the local design pressure and access the local structural strength. To achieve the strength assessment of local structure of the ship bow, the slamming design pressure results of bow bottom and bow flare areas have been selected, so as to show the calculation results of relative velocity extreme values and design slamming pressure. And then according to the slamming loads and strength assessment, the direct strength assessments have been used to check key areas. The latter is to forecast the global vertical design moment and access the global longitudinal strength through three dimension finite model.

Abstract: Fatigue assessments of container ship structures can be processed using various direct calculation approaches or various approaches of classification societies [1,2]. In this investigation, the fatigue strength assessment to the key positions of a 9200TEU container ship has been performed ,subjected to the rules of BV about fatigue strength specification of large container ships, based on design wave method and Miner fatigue cumulative damage theory analysis method. Wave loads have been computed using linear wave load calculation method based on three-dimensional potential flow theory. And the fatigue strength assessment of the typical hot spot structures has also been conducted based on a series of critical single design wave.

Abstract: Driveline gearbox includes transmission gearbox and rear axle,automotive gear oil used to lubricate gear.Take rear axle for example,through catia ,we can build three-dimensional models,and use ansa to mesh axle , then import it to fluid software fluent to analyze temperature,and obtain oil temperature curve under certain load over time;it can predict transmission efficiency and equilibrium temperature under a certain load ,and reduce gear wear and improve the operational reliability of the car.

Abstract: NURBS is a great modeling method which is supported in all the advanced three-dimensional softwares. With NURBS, people can create the lively and vivid models on the computer. And it plays a role on the model designing of chinas.combining with the experience of practices, the dissertation will analyze with cases to curved surface model of the china’s style designs and mainly study NURBS curved surface modeling taking the method of ceramic design.