力学学报

NUMERICAL SOLUTION OF SIMPLIFIED NAVIER-STOKES EQUATIONS FOR HYPERSONIC THREE-DIMENSIONAL VISCOUS FLOWS WITH CHEMICAL NONEQUILIBRIUM

In this paper the time-dependent method has been applied to the compu-tation of simplified Navier-Stokes equations for hypersonic three-dimensional viscous flowswith chemical nonequilibrium. The overall problem is decoupled into(a)a fluid mechanicproblem and(b)a chemistry problem. The coupling between the fluid mechanics and thechemistry is treated in an iterative manner. For very high Mach number the air in the shocklayer that envelops the body is at high temperature. The air may become appreciably dis- s...

1994, 26(4): 385-396. doi: 10.6052/0459-1879-1994-4-1995-560

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NUMERICAL SIMULATION OF INSTABILITY IND DRIVEN RECTANGULAR CAVITY FLOW

Numerical simulation is reported for the two-dimensional driven cavityflow with aspect ratio two. Calculation has been performed for Reyonld number from 100to 10000 on nonuniform staggered grids with the modified implicit Temam scheme andpressure correction method.When Re≤3000, steady-state solutions have been obtained;when Re≥3500, periodic asymptotic solutions have been obtained and verifed with spectralanalysis.It is shown that Hopf bifurcation occurs between Re = 3000 and 3500.

1994, 26(4): 397-406. doi: 10.6052/0459-1879-1994-4-1995-561

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AN INVESTIGATION OF SURFACE BOUNDARY CONDITIONS FOR CHEMICALLY NON EQUILIBRIUM BOUNDABY LAYERS

The general formulations of the chemically reacting surface boundary condi-tions for non-equilibrium boundary layer chemistry are derived from the theoretical analysisand their specific cases are investigated. When the ablation surface is fully catalystic to allgas phase reactions adjacent to it,the transfer coefficient approach is used to simplify thecalculations by decoupling the ablating surface procedure from a non equilibrium bound-ary layer procedure and a general method for computing the ablation su...

1994, 26(4): 407-415. doi: 10.6052/0459-1879-1994-4-1995-562

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ANALYTICAL-VARIATIONAL-CONSERVATIVE INTEGRAL METHOD IN THE SOLUTION OF IMCOMPRESSIBLE BI-METAL GLUED JOINTS WITH INTERFACIAL CRACKS

According to the theory of function of complex variables,the eigenfunc- tion expansions of displacements and stresses,satisfying the governing equations,boundaryconditions along cracked interface and conditions of continuity along uncracked interface, are derived.The conservative integrals of mixed mode for interfacial crack of imcompress-ible bi-metal and the relations between conservative integrals and stress intensity factors areestablished.Furthermore,the unknown coefficients,including stress intensity ...

1994, 26(4): 416-423. doi: 10.6052/0459-1879-1994-4-1995-563

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THE CONCEPT OF PRINCIPAL MODE SHAPES AND THE MEASURES OF CONTROLLABILITY AND OBSERVABILITY FOR MODE SHAPES WITH REPEATED FREQUENCIES

This paper studies how to measure the controllability and observability ofvibration mode shapes with repeated frequencies and how to show clearly the structure of thesubspace consisting of these mode shapes with repeated frequencies in terms of controllabilityand observability. Using singular value decomposition technique,a new set of mode shapesassociated with this repeated frequency and the corresponding singular values has beenfound out.This new set of mode shapes, called the principal mode shapes,can c...

1994, 26(4): 424-431. doi: 10.6052/0459-1879-1994-4-1995-564

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STOCHASTIC OPTIMIZATION FOR VIBRATION SYSTEMS OF MUTIL-DEGREES OF FREEDOM

A pobabilistic approach to design variables optimization of vibrationsystems with mutil-degrees of freedom is presented. The proposed method is based onmathematical modelling of the system. Optimization is understood as a calculation of themean values and standard deviations and choosing of the random parameters which in thefeasible domain minimizes the objective function. Feasible domain is defined by probabilisticconstraints.The method is illustrated for the optimization of parameters of a linear torsiona...

1994, 26(4): 432-439. doi: 10.6052/0459-1879-1994-4-1995-565

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AN ASYMPTOTIC ANALYSIS OF THE ELASTOSTATIC FIELD WITH FINITE DEFORMATION NEAR THE TIP OF AN INTERFACE-CRACK

This work investigates the behavior of a tractionfree crack at the interface of two semi-infinite slabs bonded together under the conditions of plane strain. An asymptotic solution is found by the use of the fully non-linear equilibrium theory of a new compressible elastic solids.

1994, 26(4): 440-450. doi: 10.6052/0459-1879-1994-4-1995-566

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MICRO-STATISTICAL ANALYSIS OF ULTIMATE TENSILE STRENGTH OF CROSSPLY LAMINATES

This paper investigates the ultimate failure behavior of[0/90/0]crossplylaminates under uniaxial tension.A modified shear-lag model is first proposed for solvingthe stress redistributions due to both the failure of the 90° ply and the breakage of somefibers in the 0° plies. Next,the random critical-core probability model is used to analyzemicroscopically the ultimate failure of crossply laminates. The predictions of the ultimatefailure strength of[0_2/90_m]_s and[0_4/90_m]_s graphite epoxy and [0_4/90_m]_s ...

1994, 26(4): 451-461. doi: 10.6052/0459-1879-1994-4-1995-567

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DIFFRACTION OF SH-WAVES BY A CIRCULAR CAVITY WITH A PARIIALLY DEBONDED LINER

This paper deals with the problem of diffraction of SH-waves by a circularcavity with a partially debonded liner. The debonding resions are modeled as arc-shapedinterface cracks. Using the wave function expansion method and introducing the dislocationdensity functions as unknown variables, the problem is reduced to a set of singular inte-gral equations which are solved numerically to obtain the dynamic stress intensity factors(DSIF_s), far-field displacements and scattering cross-section(SCS). The results s...

1994, 26(4): 462-469. doi: 10.6052/0459-1879-1994-4-1995-568

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THE FREE MOT1ON OF NONHOLONOMIC SYSTEM AND DISAPPEARANCE OF THE NONHOLONOMIC PROPERTY

This paper studies the definition and the condition of realization of the free motion of a nonholonomic system and disappearance of the nonholonomic property related to such motions. Three exemples are given to illustrate the application of the result.

1994, 26(4): 470-476. doi: 10.6052/0459-1879-1994-4-1995-569

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A QUALITATIVE THEORY OF JUMPING MOTION

A four-seginent model of human body is proposed in this paper for thediscussion of vertical jumping motion. Assuming the rotating angle of legs as the gelleralizedcoordinate, and the variation of the position of the ground reaction force on feet as the controlfunction, the dynanucal equations are deduced to be an autonomous nonlinear equation oflst order. Analysing the phase trajectories in phase planes of angular vefocity and angularacceleration of the leg’s rotation and the curves of control functions in ...

1994, 26(4): 477-482. doi: 10.6052/0459-1879-1994-4-1995-570

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AN ANALLYSIS OF FLOW IN ATANK WITH COMPLEX GEOMETRY BY NON-ORIHOGONL FINITE VOLUME METHOD

A numerical model based on non-orthogonal finite vloume method ispresented.The model has been used to solve the governing equations of axisymmetrical flowswith standard k-ε turbufence model. Due to the non-orthogonal grids adopted, it can beused to simulate flows in sedimentation tanks with complex geometries. Flow computationof a real tank has been performed.The calculated results agree well with the measureddata.

1994, 26(4): 483-487. doi: 10.6052/0459-1879-1994-4-1995-571

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ON THE BURST DETECTION TECHNIQUES IN WALL-TURBULENCE

A comparision of the effectiveness and sensitivity of the mu-level, VITA,WAG,(uv)_2 burst-detection algorithms has been done. Measurements were made in a waterchannel using hot-film X-probes located in the near-wall region of a flat plate. Same setof data are used in the study with conditional sampling and conditional averages. Theapproach of acquiring the unique average bursting period are discussed.

1994, 26(4): 488-493. doi: 10.6052/0459-1879-1994-4-1995-572

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A METHOD FOR CALCULAIING THE DYNAMIC EFFECT OF DYNAMIC AND STATIC FRICTION ON A CONTACTABLE CRACK

This paper proposes an explicit met hod for analyzing the dynalnical re-sponse of the contactable cracks with friction in the crack surface,The method can be usednot only to simulate the process of impaict of the crack surfaces,but also to consider theeffects of static and kinematic frictional resistance when contact-slip of crack surface occurs. Dynamical contact of an infinite crack and scattering of P wave by a contactable crack inhalf-space are calculated.The results indicate that the method in the pape...

1994, 26(4): 494-502. doi: 10.6052/0459-1879-1994-4-1995-573

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A STUDY ON THE COMPUTATION EFFICIENCY OF MARCHING/ITERATING ALGORITHM

In this paper, we made a further investigation on the method of single spacemarching and iterating, carried out locally in each crossflow plane,that was used to simulatethe 3D steady supersonic viscous flow. In each marching plane,when iterating locally alongthe pseudotime levels, we used four different implicit iterating strategies. These includethe fully implicit method,the Gauss-Sidle iteration in circumferencial direction and implicititeration in normal direction, implict in normal direction and explici...

1994, 26(4): 503-507. doi: 10.6052/0459-1879-1994-4-1995-574

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A STUDY ON ARTICLE AUTHORSOF《ACTA MECHANICA SINICA》

According to the theory of bibliometrics , through analysing and studyingstaticstal data, this paper reveals the article authors’present situation and character andthe core authors’distribution of《Acta Mechanica Sinica》,as well as the developingtrend of Mechanics by studying the“unit literature author coefficient”.These are useful forthe study and development of Mechanics and the build-up of the journal’s author group.

1994, 26(4): 508-512. doi: 10.6052/0459-1879-1994-4-1995-575

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