力学学报

THE STUDY OF FLOW OVER OSCILLATING AIRFOILS AND AIRFOILS WITH TRAILING-EDGE FLAP

The dynamic precess was numerically simulated on a two dimensional oscillating airfoil or an airfoil with trailing-edge flap in pitch. The Euler and Navier-Stokes equations with Baldwin-Lomax turbulent model were required to solve using the implicit fac-torized finite difference algorithm(LU-AD1 algorithm), which was constructed n a body fitted coordinate system. The study was focused on the unsteady effect of shock wave and control of separation on the lifting surface due to the oscillation. The numerical ...

1993, 25(1): 1-7. doi: 10.6052/0459-1879-1993-1-1995-607

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THE GASDYNAMICAL ANALYSIS OF GAS-LUBRICATED SLIDER BEARINGS UNDER HIGH KNUDSEN NUMBER CONDITIONS

A generalized lubrication equation derived from a linearized Boltzmann equation is solved by finite difference method in this paper, and the results of static characteristics and dynamic characteristics are also given Numerical analysis of the equation for high Knudsen numbers reveals three principal resul s First, a generalized lubrication equation must be used for ultra-thin gas film aod low velocity. Second, the modified Reynolds equation featuring the first-order velocity slip boundary condition overest...

1993, 25(1): 8-15. doi: 10.6052/0459-1879-1993-1-1995-608

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THE DAMAGE PROCESS OF A TENSILE ALUMINIUM PLATE UNDER THE INTENSE LASER RADIATION

The damage process, fracure observation and numerical simulation studyof a tensile aluminium plate under the intense CO2 laser radiation is presented. If is found thar cracking initiates at the intersection of the laser radiation edge and a diameter which is perpendicular to the tension direction, and then, develops outward along this diameter until faiture.

1993, 25(1): 16-21. doi: 10.6052/0459-1879-1993-1-1995-609

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TEMPERATURE DEPENDENCE OF THE GRAIN BOUNDARY RELAXATION IN ALUMINIUM BICRYSTALS

1993, 25(1): 22-28. doi: 10.6052/0459-1879-1993-1-1995-610

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THREE-DIMENSIONAL ANALYSIS OF THE CONCENTRATION IN AN ELECTROPHORESIS CHAMBER WITH CONTINUOUS FLOW

This paper studies the separation process of different particles in a suspension continuously flowing through a square electrophoresis chamber under the action of a transverse electric field. Three-dimensional temperature, velocity and concentration fields as well as their interactions are taken into consideration, for the first time, and the effects of various parameters under micro-gravity and usual gravity are demonstrated through numerical simulations. A new quasi-three-dimensional approach is proposed,...

1993, 25(1): 29-39. doi: 10.6052/0459-1879-1993-1-1995-611

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THE NUMERICAL SIMULATION OF SOLUTE TRANSFER IN SATURATED AND UNSATURATED SOIL

In the present paper, numerical simulation of solute transfer in saturated and unsaturated soil is given. The convection and dispersion terms in the equations governing water and salt motion are solved respectively by using Langrangean moving coordinate and Eulerian fixed coordinate systems. Furthermore, cubic spline interpolation method is employed for the projection from the fixed coordinate to the moving coordinate, which makes the model more exact and simpler. The comparisons with theoretical solution i...

1993, 25(1): 40-47. doi: 10.6052/0459-1879-1993-1-1995-612

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THE LARGE DEFLECTION DYNAMIC PLASTIC RESPONSE OF A NOTCHED CANTILEVER BEAM SUBJECTED TO IMPACT

The paper examines the complete solution of a rigid-plastic notched cantilever beam subjected to impact by a projectile. A group of large deflection governing equations for the double-hinge mechanisms is derived. Numerical solution for the equations is presented to calculate the permanent deformation of the beam. Finally, the distribution of the dissipated energy in the beam and the effects of the notch on its plastic deformation are discussed.

1993, 25(1): 48-55. doi: 10.6052/0459-1879-1993-1-1995-613

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THE RESPONSE OF FINITE THICKNESS SAND-BED TO WAVE LOADING

In this paper, the continuum mechanics of water-soil mixture is adoptof for analysing the response of finite thickness sand-bed to wave loading. The sand-bed is treated as a saturated porous elastic medium and Biot's theory is used to formulate the coupled flow and deformation. The waves are described by linear water waves. Under the above assumptions, the basic equations are obtained for describing the response of soil-bed to wave loading. The distribution of displacements, stresses and porewater pressures...

1993, 25(1): 56-68. doi: 10.6052/0459-1879-1993-1-1995-614

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THE EXPERIMENTAL HRR SINGULARITY FIELD OF THE STATIONARY CRACK-TIP

In this paper, the displacement and strain fields around double edge cracks are measured for different hardening materials (the strain hardening exponents n = 3.350→ 9.180) using optical methods (in-plane moire and projected moire methods). The experimental singularity fields are analyzed and compared with HRR theoretical solution. The experimental HRR singularity fields around crack-tip are obtained and their distribution with different loading and hardening exponents are discussed.

1993, 25(1): 69-75. doi: 10.6052/0459-1879-1993-1-1995-615

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COMPUTER-AIDED PHOTOELASTIC STRESS ANALYSIS

A new method of computer aided photoelastic stress analysis is presented. It has such advantages as full electronic recording, automatic stress analysis and simple optical setup. The precision is greatly enhanced by phase measuring technique. Several experimental scheme and the methods of improving the image quality are also provided. An example of diametrically loaded disk proves the validity of the method.

1993, 25(1): 76-83. doi: 10.6052/0459-1879-1993-1-1995-616

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THE BOUNDARY ELEMENT METHOD FOR SCATTERING OF TRANSIENT WAVE FOR ANISOTROPIC MEDIUM

A set of boundary integral equation (BIE) of transient waves scattering in an anisotropic medium is established by Fourier transformation and weighted residuals method, and an appropiate shape-function is also obtained in this paper. Several examples calculating the scattering displacement show that the method used for scattering high-frequency transient wave is effective.

1993, 25(1): 84-92. doi: 10.6052/0459-1879-1993-1-1995-617

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INTERACTION OF MULTIPLE SEMI-CYLINDRICAL CANYONS BY PLANE SH-WAVES IN ANISOTROPIC MEDIA

In this paper, the interactions of multiple semicylindrical canyons by SH-waves in anisotropic media are studied by using multipolar coordinate and complex function method. The effects of the geological conditions can be simulated by anisotropic media. The so-called scattering wave function of the neighborhood of the multiple semi-cylindrical canyo ns in anisotropic media is given. Using the movign coordinate system, the boundary conditions of the given multiple semi-cylindrical canyons are satisfied step b...

1993, 25(1): 93-102. doi: 10.6052/0459-1879-1993-1-1995-618

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A NON-LINEAR VISCOELASTIC-PLASTIC CONSTITUTIVE MODEL FOR GLASSY POLYMER PMMA

This paper discusses the expressions of macroscopic mechanics for theuniaxial-compression stress-strain behaviour of glassy polymer PMMA, i.e. the constitutive relations, according to the experimental data. A non-linear viscoelastic- plastic constitutive model composed of an activation dashpot by taking into account of the strain-hardening effect coupl in series with a standard linear solid or a Maxwell body is suggested. The comprehensive constitutive equations both in differential and integral forms are p...

1993, 25(1): 103-110. doi: 10.6052/0459-1879-1993-1-1995-619

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VELOCITY FIELD OF THERMOCAPILLARY CONVECTION IN LIQUID BRIDGE OF HALF FLOATING ZONE

The velocity distribution of flow field in liquid bridge is an important aspect in the thermocapillary convection driven by the gradient of free surface tension in liquid bridge. This paper presents the velocity variation for typical liquid bridge shape and applied temperature difference. The experiment results agree with the numerical simulating results. It is indicated that the vortex in the liquid bridge splits into two when the liquid bridge is slender enough.

1993, 25(1): 111-115. doi: 10.6052/0459-1879-1993-1-1995-620

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THE SINGULAR BEHAVIOUR OF POTENTIAL FLOW AROUND THE RECTANGULAR CORNERS OF FLOATING BODIES

The singular behaviour of potential flow around the rectangular corners of floating bodies is presented. It is shown that, in the linear regime, the singular behaviour of velocity potential for oscillating problem is D2/3 (D is the distance between field point and corner) and an application is given.

1993, 25(1): 116-122. doi: 10.6052/0459-1879-1993-1-1995-621

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FINITE ELEMENT METHOD BASED ON ENTHALPY FORMULATION OF CONVECTION-DIFFUSION FOR LIQUID-SOLID PHASE CHANGE PROBLEMS

A finite element method based on enthalpy formulation of convection-diffusion is developed for numerical solution of liquid-solid phase change problems. It avoids many difficulties which will appear when temperature formulation be used. The basic feature of the proposed method lies in its naturality and the simplicity. The test problems of freezing in a thermal cavity (planar and axisymmetrial problems) under natural convection are used to demonstrate the reliability and the efficiency of this method.

1993, 25(1): 123-128. doi: 10.6052/0459-1879-1993-1-1995-622

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1993 Vol. 25, No. 1

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