力学学报

A NUMERICEL SIMULATION OF ENERGY DISSIPATION IN PRESSURE CONDUITS WITH TWO PERFORATED PLATES

In this paper the turbulent flow in pressure conduits with perforated plates fordissipation is investigated.The results obtained are compared with experimental data andthe agreement between them shows that the numerical simulation is reliable。

1995, 27(6): 641-646. doi: 10.6052/0459-1879-1995-6-1995-479

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CONSTRUCTION OF AN ADAPTIVE HYBRID FORM OF TVD SCHEMES

In the present paper a number of TVD schemes are tested and compdred throughamodel equation。 Numerical results show that Some schelnes are more “compressive”andsome are more“diffusive”.To avoid the“overcompressibility” and“overdiffusion”, a newkind of TVD scheme is proposed.It is constructed in the hybrid form of a more compressiveTVD scheme and a more diffusive TVD scheme 。 With the introduction of an adaptiveweighted function,the new scheme maintains high resolution in sharp discontinuities andaVoids“o...

1995, 27(6): 647-652. doi: 10.6052/0459-1879-1995-6-1995-480

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THE STRUCTURE OF COMBUSTION DUST CLOUD WITHIN BOUNDARY LAYER INDUCED BY SHOCK WAVE

When a sufficiently strong shock wave passes over a surface laden with com-bustible particle,a combustion dust cloud will be induced within the boundary layer,whichis investigated both experimentally and theoret ically to reveal its structure,It is shownfrom the computational results that the combustion dust cloud boundary layer consists ofan induction zone, a reaction zone and a diffusion zone。 The highest particle concentrationoccurs in the induction zone。 Computed and measured results for the profile of ...

1995, 27(6): 653-662. doi: 10.6052/0459-1879-1995-6-1995-481

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MICROGRAVITY EXPERIMENT ON OSCILLATORY CONVECTION IN LIQUID BRIDGE OF SEMI-FLOATING ZONE

The inacrogravity experiments of oscillatory covection in liquid bridge of halffloating zone were carried out by using the 800 meter drop facility in the Japan Macrograv-ity Center,The coordinated measurements of typical physical quantities such as internaltemperature,flow field,edge variation of free surface boundary and free surface wave wererealized.The experimental results comprise the traiisition of oscillatory covection fromEarth’s gravity to microgravity environment and show that the oscillatory feat...

1995, 27(6): 663-670. doi: 10.6052/0459-1879-1995-6-1995-482

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STRESS ANALYSIS OF VISCOELASTIC COMPONENT BY THE HYBRID METHOD

The measurement of optical and mechanical parameters of viscoelastic materialshas been explained in detail.A new routine to solve time dependent principal stress bythe hybrid method of boundary element and photoviscoelasticity has been suggested.Anexample of viscoelastic simply supported beam has been analyzed.

1995, 27(6): 671-680. doi: 10.6052/0459-1879-1995-6-1995-483

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A DAMAGE MECHANICS MODEL FOR DESCRIBING NONLINEAR BEHAVIORS OF BRITTLE MAIERIALS

In this investigation,a mechanical model is developed for the characterizationof inelastic mechanical responses in brittle materials due to damage when the time and ratedependent behaviors are insignificant。The formulation is based on the concepts of damagesurface and damage potential.The approach makes the derivation of evolution law of thematerial coefficients and the anisotropic constitutive equation of the brittle materials pos-sible, based on the assumption that the changes in material properties due t...

1995, 27(6): 681-690. doi: 10.6052/0459-1879-1995-6-1995-484

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PLANAR TEXTURE EVOLUTION AND PLASTIC RESPONSE IN CRYSTALLINE POLYMERS

Proposes an analytical method for describing planar texture evolution andplastic responses in idealized crystailine polymers. The Taylor model is modified to take intoaccount the inextensibility of regtilarly foldetl molecular chains。 We introduce a continuousorientation distrihution function and represent it in the form of irreducible tensors.Theevolution equations for the tensor coefficients are derived and solved to obtain the evolvingtexture and the macroscopic respoiises of the material. The present mo...

1995, 27(6): 691-701. doi: 10.6052/0459-1879-1995-6-1995-485

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STRUCTURE TENSOR OF QUATERNION MULTIPLICATION AND TENSOR EXPRESSIONS OF QUATERNION MATRICES

The tensor concept of quaternions has been expounded and the relations betweenquaternion matrices and quaternion tensors have been set up with the aid of the structuretensor of quaternion multiplication, thus the quaternion calculus can be converted into theordinary tensor calculus.

1995, 27(6): 702-710. doi: 10.6052/0459-1879-1995-6-1995-486

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THE NUMRICAL ANALYSIS OF OPTIMAL CONTROL ON STRUCTURE DEFORMATION

Structure that can respond to enviroment appropriately by itself is calledsmart structure,e.g.plate containing piezoceramics. In this paper, FEM was formulatedhmeans of electro-mechanical variational equations and the procedure to get relationshipbetweell voltage on piezoceramic and structure deformation,i.e. control matrix,waJs alsoestablished.Using optimal method, optimal control of structure deformation was achievedwith consideration of no or some restricted conditions.

1995, 27(6): 711-718. doi: 10.6052/0459-1879-1995-6-1995-487

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AGREEMENT OF THE INFINITE ELEMENT METHOD AND THE ANALYTICAL METHOD FOR CHAIN OF IDENTICAL SUBSTKUCTURES AND THE SOLUTION OF TRANSLATIVE MATRIX

An agreement of the infinite element method and the analytical method for the chain of identical substructures is discussed in this paper.Ageneral solving program isgiven,which is based on reference[1]and[2]and can be applied to LQ control problems。Moreover,in this paper is the translative metrix X is solved directly by iderative method,which is very simple and accurate。

1995, 27(6): 719-723. doi: 10.6052/0459-1879-1995-6-1995-488

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PRINCIPLE AND APPLICATIONS OF DIGITAL SPECKLE CORRELATION METHOD

This paper presents theoretical description for digital speckle correlation methodwhich is based on variational and image recognition principle。The problem of deformationmeasurement is then converted into a pure numerical computation, in which the difficultiesdue to interferometric fringes in conventional optical methods can be avoided.Primaryexperiments indicated that the method can be applied in engineering environments,andis capable of measuring deformations quantitatively in high speed dynamic process a...

1995, 27(6): 724-731. doi: 10.6052/0459-1879-1995-6-1995-489

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NUMERICAL SIMULATION FO INCOMPRESSIBLE ASYMMETRIC TURBULENT VORTICAAL FLOW

The method of pseudocompressiblity is used in solving the three-dimensionalsteady incompressible Navier-Stokes flows。The solution procedure employs the Beam-Warming implicit approximate factorization scheme。The Baldwin-Lomax algebraic tur-bulent model together with the Degani-Schiff modiffication is used for Reynolds-averagedNavier-Stokes equations to numerically simulate the high-incidence, great Reynolds number,vortical flow about a tangent-ogive cylinder the asymmetric numerical results are in goodagreem...

1995, 27(6): 732-736. doi: 10.6052/0459-1879-1995-6-1995-490

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ON OPTIMAL PAIH OF LINEAR VISCOELASTIC STRUCTURES

We discussed the optimal path of two kinds of structures:(1)three dimensionalseparable variable viscoelasticity; and(2)truss.we have shown:1) the optimal deformationpath of viscoelasticity(Maxwell material)is linear on(0,T)and only suffers jump discontin-uance at t = T. We also pointed out the mistakes of some previous studies;2) the optimalloading path of a truss (Maxwell material)is an impulsive one。

1995, 27(6): 737-741. doi: 10.6052/0459-1879-1995-6-1995-491

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ARBITRARILY POLYGONAL 2-D FINITE ELEMENTS

At present, the computational analysis of micromechanics used to single crystalis to divide a crystai into many triangular or quadrilateral finite elements. If we use thismethod to analyze polycrystalline materials, the computation work will be too massive。Experimental observations show that the deformation and slide state vary slowly inside everycrystal of the polycrystalline material. Therefore each crystal may be idealized to a polygonalelement and each crystal interface to an interface eleinent, in so d...

1995, 27(6): 742-746. doi: 10.6052/0459-1879-1995-6-1995-492

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A NEW TEST METHOD FOR SHEAR BUCKLING OF A CYLINDRIC SHELL

A new method for the experiment on shear buckling of cyindric shell of R 1000mm using two curved plates is presented.The method saves experimental materials with the help of the coinpact fixtures andsimple equipments,its principle is very clqar and torque equipments are not used.Thetestingresults of this paper are rather exact and in good agreement with the results ofpublished works。

1995, 27(6): 747-753. doi: 10.6052/0459-1879-1995-6-1995-493

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ACOUSTIC EMISSION CHARACTERISTICS OF A3 STEEL DURING DAMAGE ACCUMULATION

To reveal the characteristics of acoustic emission(AE) for ductile materialsduring damage accumulation,a series of tests were carried out in our laboratory. Thispaper presents several AE results about static and fatigue loading induced damage behaviorfor A3 structural steel.Different AE properties are discovered when A3 steel underwenttension,fatigue and then tension。 Two peaks in the AE counts vs.time imply differentdamage states for the specimen during static loading after fatigue,yielding and damageaccum...

1995, 27(6): 754-758. doi: 10.6052/0459-1879-1995-6-1995-494

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1995, 27(6): 759-760. doi: 10.6052/0459-1879-1995-6-1995-495

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1995 Vol. 27, No. 6

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