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1.
祝效华  李柯 《应用力学学报》2020,(1):128-133,I0008
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。  相似文献   

2.
3.
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, Gs 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, Gs; 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  相似文献   

4.
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.  相似文献   

5.
Belostokskii Polytechnic Institute, Poland. Translated from Prikladnaya Mekhanika Vol. 26, No. 11, pp. 99–104, November, 1990.  相似文献   

6.
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.  相似文献   

7.
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.  相似文献   

8.
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.  相似文献   

9.
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.  相似文献   

10.
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.  相似文献   

11.
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.  相似文献   

12.
Institute of Hydromechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Prikladnaya Mekhanika, Vol. 24, No. 7, pp. 77–83, July, 1988.  相似文献   

13.
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.  相似文献   

14.
亚微米炸药的感度选择性   总被引:8,自引:0,他引:8  
采用亚微米粉体炸药 (0 .1~ 1 m )与普通粉体炸药 (1 0 m )进行了落锤撞击感度和冲击片 (高压短脉冲 )起爆感度对比试验 ,发现亚微米粉体炸药有在常见环境力 (一般的撞击、摩擦 )条件下比较安全 ,而在特定激励 (冲击片 )作用下起爆可靠性提高的感度选择性特点 ,并从理论上对上述特性进行了探讨。研究表明 ,亚微米粉体炸药具有非常好的应用前景。  相似文献   

15.
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.  相似文献   

16.
Experimental results are presented concerning the effect of the air blow-in rate on the size of the flow separation region downstream of a rearward-facing step at different step heights. The stream function is found from the experimental velocity profiles, the streamline = 0 being taken as the boundary line. It is shown that the separation region increases as the blow-in rate is increased. Generalization of the experimental results for different blow-in rates and step heights has made it possible to obtain an analytical expression describing the location of some characteristic lines in the separation region (boundary streamline, reverse-flow boundary, line of reverse-flow maximum velocity, line of variable-velocity layer thickness, and the displacement thickness line). Velocity profiles are obtained by means of a hot-wire anemometer. Analytical expressions are written as polynomials with unknown coefficients. The results obtained may be helpful in developing techniques for the treatment of heat transfer under flow separation conditions.  相似文献   

17.
The article gives the results of a study of the motion of bubbles and their deformation near the heating surface at different pressures. It was observed that, during the time of their growth, the gaseous medium in the bubbles is in a compressed state.Nomenclature R) radius of bubble - Rh) maximul radius of a deformed bubble in the horizontal plane - Rv) maximal radius of a deformed bubble in the vertical plane - ) specific weight - B) universal gas constant - ) surface-tension coefficient - p) pressure - ) edge wetting angle - g) acceleration due to gravity - V) volume - ) molecular weight - CT) isothermal velocity of sound Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 77–81, July–August, 1971.  相似文献   

18.
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.  相似文献   

19.
The inverse scattering theory is applied to determine the continuous variation of the elastic parameters of spherically symmetric flaw which is located within an isotropic and homogeneous host medium. From the angular dependence of the scattering amplitude, the phase shift for the transverse wave with polarization perpendicular to the scattering plane can be deduced for different partial waves. The knowledge of this set of phase shifts for two frequencies enables one to obtain the radial variation of the density and the shear modulus parameters of the flaw from the solution of a special difference equation which approximates the differential equation for the displacement of the transverse mode. The method has been applied successfully to obtain several different profiles for the density and the shear modulus parameters.  相似文献   

20.
The singularities of the boundary layer equations and the laminar viscous gas flow structure in the vicinity of the convergence plane on sharp conical bodies at incidence are analyzed. In the outer part of the boundary layer the singularities are obtained in explicit form. It is shown that in the vicinity of a singularity a boundary domain, in which the flow is governed by the shortened Navier-Stokes equations, is formed; their regular solutions are obtained. The viscous-inviscid interaction effect predominates in a region whose extent is of the order of the square root of the boundary layer thickness, in which the flow is described by a two-layer model, namely, the Euler equations in the slender-body approximation for the outer region and the three-dimensional boundary layer equations; the pressure is determined from the interaction conditions. On the basis of an analysis of the solutions for the outer part of the boundary layer it is shown that interaction leads to attenuation of the singularities and the dependence of the nature of the flow on the longitudinal coordinate, but does not make it possible to eliminate the singularities completely.  相似文献   

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