Advanced Materials Research Vols. 594-597

Abstract: Based on the flow model and its mathematical description in curvilinear coordinates, the steady and fully developed laminar flow in the curved pipe of square cross-section was simulated by the Galerkin method. The results show that the eye points of the secondary flow vortex at low Reynolds numbers almost locate at the position of 0.457 on the vertical axis, the axial velocity maximum shifts inward or outward when the pipe curvature parameter and flow conditions change. Furthermore the bifurcation flow is studied to draw the bifurcation state diagram, and the Reynolds number corresponding to the bifurcation point of the four-vortex solution is accurately equal to 300.1.

Abstract: A problem related to widespread accepting GW model is that there is no analytical expression for the parameters of interest at the interface. The probability density of asperity heights for closely 90% of engineering surfaces tends to be Gaussian. Taking GW model simple exponential probability density to approximate the Gaussian one is not explicit for some conditions. Many practical closed form analytical expressions were derived for the contact load, contact area and contact spot number for GW elastic contact model.

Abstract: The meshless finite volume method was employed to enforce the conservation of momentum in a local weak form. A novel hybrid meshless finite volume method (HMFVM) was proposed. The displacement and the stress were interpolated independently with a hybrid scheme in the process. To enforce the compatibility between stress and displacement, a smoothing stress was introduced via finite volume method. In this way, the HMFVM can avoid the appearance of derivatives of shape functions and improve the efficiency over the orthodox meshless finite volume method. Then, the HMFVM was applied to some Elasto-plastic problems, illustrating that it enjoys high precision and efficiency. As a result, the derivatives of shape function are avoid absolutely.

Abstract: In the paper the need of virtual assembly property analysis was discussed，the indexes system of the product assembly properties was constructed based on assembly force. The mechanical model of strength and reliability analysis was established for hole and axle interference fit joint in virtual assembly. The mechanical model of strength and reliability analysis was established for key joint. The analysis and inspection technology of the product assembly properties for virtual assembly was put forward based on assembly force. The system of product assembly properties analysis was developed, and the system was tested by gear reducer.

Abstract: In the present study, the constitutive law of the deformation theory of plasticity has been derived. And that develop the two-dimensional and three-dimensional finite element program. The results of finite element and analytic of plasticity are compared to verify the derived the constitutive law of the deformation theory and the FEM program. At plastic stage, the constitutive laws of the deformation theory can be expressed as the linear elastic constitutive laws. But, it must be modified by iteration of the secant modulus and the effective Poisson’s ratio. Make it easier to develop finite element program. Finite element solution and analytic solution of plasticity theory comparison show the answers are the same. It shows the derivation of the constitutive law of the deformation theory of plasticity and finite element analysis program is the accuracy.

Abstract: Based on the fast fourier transform（FFT） and flexibility matrix method, the study is presented for journal bearing elastohydrodynamic lubrication. The effects of FFT and flexibility matrix method on the distribution of oil film pressure and elastic deformation in the steady load are investigated. The results are shown that the difficulty of the EHL for journal bearings in the case of high eccentricity ratios or heave loads can be effectively solved by the FFT method. When the eccentricity ratio is smaller, the magnitude and distribution of the oil film pressure are basic agreement by FFT method and flexibility matrix method. When the eccentricity ratio enhances, the maximum oil film pressure obtained by FFT method is bigger on both ends of the journal bearing and on its intermediate is smaller.

Abstract: The original definition of material derivative is changing rate relative to the time of a physical quantity which belongs to a fluid particle. But when studying fluid mechanics problems, need in certain cases to calculate the material derivative of some quantities which don’t belong to a fluid particle, such as calculating the material derivative of base vectors of orthogonal curvilinear coordinate system. The original definition of material derivative isn’t suitable for these quantities. Calculating material derivative of these quantities is not clear in concept. To solve this problem, thorough analysis about material derivative was made according to the original definition and calculation formula of material derivative. Results found that the concept of material derivative can be extended and so can apply to any quantities which don’t belong to a fluid particle and are defined in flow fields, including vector or scalar, physical quantities or non physical quantities.

Abstract: After polymer flooding has been put into effect in Daqing oilfield, eccentric wear of sucker rod and tubing has been so serious that it made the rods break. In order to analyze the cause of eccentric wear based on the upper-convected Maxwell model, the flow equation of viscoelastic fluid in eccentric annulus was established in cylinder coordinate system. Then the equation was transformed in bipolar coordinate system and dispersed by control-volume method. The velocity distribution was solved by ADI methods and example was calculated which provides theory basis for solving eccentric wear problems.

Abstract: Based on review of current study on pile foundation under lateral load, an introduciton is given to some theoretical methods commonly used at home and aboard, with emphasis placed on the elastic subgrade reaction method and the p-y method as well as their characteristics and applicability, and some problems needed for further study are put forward. The present study provides a train of thought for further research on the behavior of large-diameter pile under lateral load.

Abstract: After polymer flooding was put into effect in DaQing oilfield, eccentric wear of sucker rod and tubing has been so serious that it made the rods break. This is because production liquid produced from normal wells is pure viscous fluid while liquid produced from polymer flooding oil wells is viscoelastic fluid. The flow equation of viscoelastic fluid in eccentric annulus was established in cylinder coordinate system, and the velocity distribution was solved. Based on upper-convected Maxwell constitutive equation, the normal stress calculating model of viscoelastic fluid acting on sucker rods was established. The normal stress of viscoelastic fluid acting on inner rod in eccentric annulus was measured under different experimental conditions indoors. The result proves that normal stress is the main reason of eccentric wear.