力学学报

A WIND-TUNNEL STUDY OF WIND LOADING ON COOLING TOWERS OF SHA-LIN-ZI POWER STATION

In this paper the results of wind tunnel testing of fluctuating as well asmean pressures on models of four neighboring cooling towers of Sha-Lin-Zi Power Station, arranged nearly in line under directions of prevailing wind and of peak speed are presented and discussed. It shows that, the peak suction (mean pressure) of certain towers, due to proximity interference, will be moderately greater, and the fluctuating pressure (rms value) of downstream towers, due to wake interference, may be several times larger...

1992, 24(2): 129-135. doi: 10.6052/0459-1879-1992-2-1995-720

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DIRECT NUMERICAL SIMULATION OF COHERENT STRUCT-URES IN TWO-DIMENSIONAL MIXING LAYER

This paper is to investigate the coherent structures of two-dimensionatemporally evolving mixing layer by direct numerical simulation (DNS) of Navier-Stokes equations using pseudospectral method. To avoid imaging error, mapping function designed by Cain et al. is used here to transform the original infinite region to a finite domain.The approach explains numerically the important role of fundamental perturbation wave-and its subharmonic wave in the formation, development and interaction of coherent structur...

1992, 24(2): 136-144. doi: 10.6052/0459-1879-1992-2-1995-721

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THE WAYS OF THE FORMATION OF THE HORSESHOE VORTEX IN TURBULENT BOUNDARY LAYER

Experimental observation and measurement were performed for the horseshoff ortex in turbulent boundary layer through using a new method of visualization-moving sheet of laser light and several experimental skills. It was discovered and described that the horseshoe vortices form in four ways: secondary instability, combination, deformation and burst. The formation and development of these horseshoe vortices were studied and compared. The test results show that these horseshoe vortices are different in size, ...

1992, 24(2): 145-151. doi: 10.6052/0459-1879-1992-2-1995-722

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A GENERAL KINEMATICAL ANALYSIS OF NONPROPORTIO-NAL DOUBLE SLIP

This paper presents a general kinematical analysis for nonproportionaldouble slip in fcc and bcc crystals. The analytical formulas for the deformation gradient arc obtained for bilinear path double slip and piece-wise proportional double slip. The purely kinematical equation for the tangent vector of a line element is derived.The axis rotations on a stereographic projection are illustrated for several different slip-system combinations, initial axis positions in both fcc and bcc crystal.An accurate numerica...

1992, 24(2): 152-161. doi: 10.6052/0459-1879-1992-2-1995-723

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A 3-D COMPOSITE CONSTITUTIVE MODEL FOR ANALYSIS OF FINITE ELASTO-PLASTIC DEFORMATION

In this paper, the 3-D composite constitutive model proposed in Reference[1] is extended to analyze finite elasto-plastic deformation. Constitutive equations and explicit incremental stiffness tensors for the Updated Lagrangian solution and the Total Lagrangian solution are derived and used to predict the nonuniform and localized deformation of ductile single crystals subjected to tensile loading. The obtained results are in good agreement with the experimental data[2] and predictions of previous crystal th...

1992, 24(2): 162-170. doi: 10.6052/0459-1879-1992-2-1995-724

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FREE VIBRATION OF NONCIRCULAR CYLINDRICALSHELLS WITH ARBITRARY BOUNDARYCONDITIONS

By a new coordinate transbormation function, the cylindrical shell witharbitrary shaped section can be mapped into a circular cylindrical shell and then the free vibration of the circular cylindrical shell is only investigated with the aid of the characteristic beam vibration functions. Detailed results of applications to oval and U-shaped cylindrical shells are presented. The versatility and accuracy of the method are amply demonstrated through a number of worked examples.

1992, 24(2): 171-179. doi: 10.6052/0459-1879-1992-2-1995-725

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FINITE ELEMENT DYNAMIC ANALYSIS OF FLEXIBLE MANIPULATOR ARMS WITH VISCOELASTICDAMPING

A general approach, based on the principle of virtual work in dynamics,is presented for dynamic analysis of flexible manipulator arms with viscoelastic damping, and the finite element dynamic equations which are time-dependent differential-integral equations are developed. A recurrence formulation for numerical integration of the equations is obtained.

1992, 24(2): 180-190. doi: 10.6052/0459-1879-1992-2-1995-726

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THE INVESTIGATION OF THE METAL DAMAGE AT THE CREEP BY THE METHOD OF ELECTRICAL RESISTANCEMEASURING

In this paper the method of damage measurement of metal structure atthe creep is proposed. In contrast to other methods, it allows to carry out the measurement of this damage in the process of creep test without unloading and cooling of specifens. Experimental damage curves during creep are obtained as a result of test data processing by the suggested method. The analysis of these curves leads to a conclusion that the material damage at rupture is monotonically decreasing function of applied stress. This co...

1992, 24(2): 191-196. doi: 10.6052/0459-1879-1992-2-1995-727

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COMPUTER SIMULATED ANALYSES ON DEFORMATION AND FRACTURE OF NON CRACKED AND CRACKEDSPECIMENS

A unified damage and fracture model, the combinatory work density model, which is suitable for both non-cracked body and cracked body has been su-ggested[5-7] by the authors of this paperIn the present paper, the deformation and fracture of the two kinds of tensile specimen and TPB specimen made of Steel 40Cr have been simulated by using the new model combined with large elastic-plastic deformation finite element method. The results represent the whole deformation and fracture processes of the specimens in ...

1992, 24(2): 197-206. doi: 10.6052/0459-1879-1992-2-1995-728

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ANTI-PLANE WAVE MOTION IN FINITE ELEMENT MODEL

In this paper, the equation of anti-plane wave motion in a two-dimensional finite element model is first separated into two one-dimensional simultaneous equations by-means of the separating variable method, analytical solutions of the above equations are ob-tained. According to the solutions, various aspects of the wave propagation in the discrete model is finally systematically studied: dispersion, cut-off frequency, parasitic oscillation and appendent anisotropic properties of wave propagation. In additio...

1992, 24(2): 207-215. doi: 10.6052/0459-1879-1992-2-1995-729

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SINGULAR ANALYSIS TO THE SOLUTION OF THE RICCATIDIFFERENTIAL EQUAT

The Riccati differential equation of finite duration is considered in thipaper. The solution is closely related to the variational principle and the correspondent interval mixed energy. Instead of the numerical integration method, the assembling and condensation method to the interval mixed energy can be used to the solution. The boundary condition at t can be processed at the last step, such that the difficulty of beginning integration from the singular point can be avoided. And the singular property at tj...

1992, 24(2): 216-222. doi: 10.6052/0459-1879-1992-2-1995-730

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NUMERICAL SIMULATION OF THE INTERACTION BETWEEN A PAIR OF INCIDENT VORTICES AND A CIRCULARCYLINDER

The interaction between a pair of incident vortices and a circular cylinder has been simulated numerically by using a fast vortex method in present paper. A secondary and a tertiary vortices separated from the cylinder surface are, induced by the incident yortex, observed. Because of pairing with the secondary one, the incident vortex changes its trajectory. The 'rebounding' phenomenon of the incident vortex is attributed to the effect of secondary vortex. This phenomenon has been vertified by flow visualiz...

1992, 24(2): 223-228. doi: 10.6052/0459-1879-1992-2-1995-731

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A PARALLEL ALGORITHM FOR EIGENVALUE PROBLEMS OF LARGE-SCALE STRUCTURES

In this paper, a parallel algorithm for calculating natural frequenciesand mode shapes of large structural systems is presented. In the process of subspace iteration, the method uses only substructure stiffness and mass matrices to carry out condensation concurrently and to get new iterative basis vector finally until the convergence is realized. The program of this algorithm has been realized on ELXSI-6400 parallel computer of Xian Jiao-tong university. The computational results show the computing time and...

1992, 24(2): 229-232. doi: 10.6052/0459-1879-1992-2-1995-732

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SEVERAL FIXED RIGID LINE PROBLEMS IN ANTIPLANEELASTICITY

In this paper, the fixed rigid line problem in antiplane elasticity is discussed. By means of using conformal mapping, several solutions concerning the fixed rigid line problems of half-plane are obtained. Stress singularity coefficients are derived for the investigated examples.

1992, 24(2): 233-239. doi: 10.6052/0459-1879-1992-2-1995-733

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THE EFFECT OF TRANSVERSE SHEARING DEFORMATIONSON BUCKLING AND POST-BUCKLING OFANNULAR PLATES

The effect of transverse shearing deformations on the buckling and post-buckling of annular plates is studied by using the bifurcation theory and the shooting method-

1992, 24(2): 240-246. doi: 10.6052/0459-1879-1992-2-1995-734

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SINGULARITIES IN ANiSOTROPIC COMPOSITES

In this paper, according to the theory of eigenvalue and eigenfunctionexpansion in anisotropic materials, using very simple forms of matrices, the eigenequations of stress singular orders are established on laminar wedges and cracks terminating at interface. The stress singular characteristics are discussed, the stress singular orders of all cases are calculated.

1992, 24(2): 247-252. doi: 10.6052/0459-1879-1992-2-1995-735

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FURTHER REMARKS ON THE NONHOLONOMIC DYNAMICS

Further comments on the Clielaev model and the Vacco model of the non-holonomic dynamics are presented. A conclusion of irrationality of both models is drawn. Answers to the contention of the paper [9] are given as well.

1992, 24(2): 253-257. doi: 10.6052/0459-1879-1992-2-1995-736

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1992 Vol. 24, No. 2

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