隔水管弯曲对钻柱振动影响的计算与分析

海洋油气资源钻探中隔水管的弯曲对钻柱振动以及钻进特性有特别的影响。为得到隔水管弯曲对钻柱振动的影响规律,对南海已钻深水井使用非线性有限元软件建立全井钻井数值计算模型,研究获得了不同垂深时隔水管弯曲对钻柱振动特性的影响规律。研究表明:隔水管弯曲会加剧钻柱的振动,钻柱振动加剧会导致钻井能耗上升、钻头切削能力下降并且会加快钻柱疲劳;当隔水管的弯曲达到某临界值,钻柱与隔水管间的接触力会陡增;井口的钩载越大,隔水管弯曲带来的井口钩载波动量越大;井越深,隔水管弯曲对全井钻柱最大弯矩和钻头切削能力的影响越小。     

On the study of the initiation of the micro crack on the smooth surface of polycrystalline

Crystallographic plasticity was applied to study the initiation of micro cracks on the smooth surface of polycrystalline under uniform applied stress. Even under the uniform external stress, due to the different crystallographic orientations of the grains in the polycrystalline, there is un-uniform stress distribution and the deformation is also not uniform. Under the fatigue loading, the roughness increases with the number of fatigue, and deformation will localize in some places, where micro cracks form.     

On the existence of the derivative of the volume average

A general theorem on the derivative of the volume average is formulated and proved. Conditions for the existence of the derivative are presented and discussed. This is done in order to give a better base to the theory of spatial averaging.Latin Letters E ₃ three-dimensional vector space over the field of real numbers - K, K(x) averaging domain - G, G _w, G_s open sets in E ₃; components of the two-phase system - C ¹(G) the set of functions 1-times continuously differentiable in G - W1/2(G) Sobolev space - V volume of the domain K - f function defined in G, G _w - K _infi ^sup* (x), K _infi ^sup– (x) special parts of K(x) Greek Letters boundary of G, G _w, G_s; w-s interface - _ij Kronecker delta - v unit outward normal of G, G _w - _j j-dimensional Lebesgue measure Other M closure of a set M in the metric space E ₃ - f phase average of f for the w-phase - (u, v) scalar product of u, v in E ₃ - one-sided derivatives     

Hydraulic modeling of the flow in the delta of the River Neva and in the eastern part of the Gulf of Finland

In connection with the construction of Leningrad's flood defenses the flow in the mouth of River Neva has been investigated on hydraulic models of different scales both unpressurized (see, for example, [1, 2]) and pressurized (see, for example, [3]). Since the results of these investigations are being intensively debated in connection with the discussion of the effect of defensive structures on the ecology of the Leningrad region, it is important to analyze the scientific basis for the hydraulic modeling of such flows.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 57–65, September–October, 1990.     

Determination of the additional-loading modulus within the framework of the theory of slip

Belostokskii Polytechnic Institute, Poland. Translated from Prikladnaya Mekhanika Vol. 26, No. 11, pp. 99–104, November, 1990.     

Connection between the characteristics of the signal of a shadow instrument and the spectrum of the turbulence

The shadow method is one of the most widely used methods for investigating turbulence [1, 2]. Using a shadow instrument with photoelectric recording, there exists, in principal, the possibility of finding the statistical characteristics of the turbulence from the statistical characteristics of the random signal taken from the instrument. In the present work, an investigation is made of the connection between the mean value and the scattering of the signal of a shadow instrument and the energy spectrum of optical inhomogeneities in the medium.     

Calculation of the flow in the blade passages of pump-turbines on the basis of solutions of the direct axisymmetric problem of the theory of hydrodynamic machinery

The direct axisymmetric problem of the theory of hydrodynamic machinery is considered for flows in the turbine and pump regimes. In formulating and numerically solving the problem the conditions at the edges of the blade systems [7, 8] expressing the principal conservation laws are taken into account. The three-dimensional pressure distribution in the blade systems is calculated using the asymptotic relations [1, 9]. The results of the calculations are presented and the theoretical and experimental data on the flows in the blade passages of high-speed pump-turbines are compared.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No, 4, pp. 12–19, July–August, 1988.     

Investigation of the dynamics of the development of cracks by the method of photoelasticity

An experimental investigation was made of the process of the development of cracks in two materials: polymethyl methacrylate and a polymerized epoxy resin. For these materials, determinations were made of their optical and mechanical characteristics, such as density, the speed of sound, the critical value of the coefficient of singularity of the stress field at the tip of cracks. As the dynamic characteristic of the process of the development of cracks, an investigation is made of the dependences connecting the coefficient of the singularity of the stress field at the tip of a moving crack and the rate of development of the crack. The question of the interaction between two cracks moving in a previously elongated sample is discussed.     

Visual representation of the kinematics of the continuum

The purpose of this paper is to present some experimentally determined properties of the continuum. The development starts with the illustration of deformed shapes, or metamorphoses, and the introduction of the concept of displacement. From there on, the development follows the classic mechanics-of-continuum presentation, spatial and time derivatives of displacement, strains, stresses and rigid rotations. To unify the presentation, all considerations are applied to the case of a circular ring subjected to diametral compression. Particular advantage is taken of grids, moiré, brittle-coatings and photoelasticity methods to obtain the physical representations of the properties. The following loci are considered: isokinetics, isothetics, isogonics, isoclinics of displacement, displacement trajectories, loci of partial derivative, isogyros, isotenics, isochromatics, isoclinics of strain and stress, isostatics, isopachics, isobars, isostrophics and isoentatics. The understanding of the properties of these fields helps in the visualization of the mechanics of the continuum, in general, and may prove to be particularly useful in the fields of plasticity and finite strain.     

Asymptotic behavior of the unknowns at the solving of the plane problem of the longitudinal deformation of an elastic semiband by the superposition method

Institute of Hydromechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Prikladnaya Mekhanika, Vol. 24, No. 7, pp. 77–83, July, 1988.     

Influence of the distribution of suction on the structure of the turbulent boundary layer

In this paper we present the results of an investigation of the influence of distributed suction on the structure of a turbulent boundary layer in an aqueous medium. It is shown that with increasing suction rate, the completeness of the profile increases while the pulsation intensity of the longitudinal velocity component decreases.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 10, No. 3, pp. 127–129, May–June, 1969.     

Effect of the impulse of a meteorite on the dimensions of the impact crater

Formulas for the diameter and depth of an explosion crater are obtained which take into account the energy and impulse of the explosion products, rock strength, burial depth of the explosive charge, and gravity. Using the explosive-shock analogy, the obtained relations are extended to the case of meteorite (impactor) impact on the planet’s crust (target). It is shown that in the gravity cratering regime, the influence of the impulse of the impactor is significant and increases with increasing its size. In the strength cratering regime, the impulse has little effect on crater dimensions. It is established that crater dimensions are determined mainly by the kinetic energy of the impactor and, to a lesser degree, by its impulse.     

On the formulation of the problem of the motion of a body in water

The selection of solutions describing steady irrotational flow of an ideal incompressible fluid over bodies is considered. The selection is based on restrictions that follow from the physical properties of a real fluid and from the presence of a boundary layer on the body. In particular, for any body one can specify a minimal Euler number below which flow without cavitation becomes physically impossible. In the limiting case of an Euler number equal to zero, only the Kirchhoff scheme is physical admissible, and the cavity section tends to a circle. An equation is derived for the limiting shapes of cavities at small cavitation numbers, and a comparison is made with known results.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 19–26, September–October, 1980.     

A study on the period of the free lateral vibration of the beam bridge by the theory of the orthotropic rectangular plate

Conclusion The frequency of the right, simple beam bridges is discussed by the laboratory study on the model beam bridges and the field tests on existing beam bridges in this paper, but furthermore, the application to the skew beam bridge or to the continuous beam bridge and the problem of forced vibration should be studied.Even if more exact studies are necessary, it is made sure by the study in this paper that the theory of the orthotropic plate is proper to the analysis of the free lateral vibration of the beam bridge and sufficient enough for practical purpose, especially for the beam bridge of which the width is almost equal to the span.     

Investigation of the effect of the separation zone on the vibrations of a cone

A numerical experiment has been carried out to determine the decisive factor in the loss of dynamic stability by a cone with a circular conical stabilizer. It is shown that the inertia of the separation zone formed on the lateral surface of the cone can play this role.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 190–191, January–February, 1987.     

On the Global Geometric Structure of the Dynamics of the Elastic Pendulum

We approach the planar elastic pendulum as a singular perturbation of the pendulum to show that its dynamics are governed by global two-dimensional invariant manifolds of motion. One of the manifolds is nonlinear and carries purely slow periodic oscillations. The other one, on the other hand, is linear and carries purely fast radial oscillations. For sufficiently small coupling between the angular and radial degrees of freedom, both manifolds are global and orbitally stable up to energy levels exceeding that of the unstable equilibrium of the system. For fixed value of coupling, the fast invariant manifold bifurcates transversely to create unstable radial oscillations exhibiting energy transfer. Poincaré sections of iso-energetic manifolds reveal that only motions on and near a separatrix emanating from the unstable region of the fast invariant manifold exhibit energy transfer.     

On the nonlinear dynamics of the traveling-wave solutions of the Serre system

We numerically study nonlinear phenomena related to the dynamics of traveling wave solutions of the Serre equations including the stability, the persistence, the interactions and the breaking of solitary waves. The numerical method utilizes a high-order finite-element method with smooth, periodic splines in space and explicit Runge–Kutta methods in time. Other forms of solutions such as cnoidal waves and dispersive shock waves are also considered. The differences between solutions of the Serre equations and the Euler equations are also studied.