力学学报

NUMERICAL INVESTIGATION OF THE MECHANISM FOR ASYMMETRIC VORTEX FLOWS

A robust iterative method suitable for the numerical simulation of high angie-of-attack vortex flows is established based upon the multiple line-vortex method (MLVM). With given symmetric or asymmetric locations of separation lines, the first converged solution at angle of attack as high as 60?is obtained by using the present method. Numerical experiments for a tangent-ogive forebody indicate the viscous onset mechanism of asymmetric vortex flows over body of revolution at high angles of attack and zero sid...

1990, 22(5): 513-518. doi: 10.6052/0459-1879-1990-5-1995-979

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A STUDY ON NON-STEADY FLOW OF UPPER-CONVECTED MAXWELL FLUID IN TUBE

The transient response of an upper-convected Maxwell fluid flow in a circular tube is investigated by the method of Kantorvich and that of finite difference. With the help of the constitutive equation of the Maxwell fluid the equation of motion is reduced to a, partial differential equation of hyperbolic type. The solution of the problem by the variational method is in good agreement with the numerical results by the difference scheme. The results show that the variational method of Kantorovich is suitable ...

1990, 22(5): 519-525. doi: 10.6052/0459-1879-1990-5-1995-980

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THE BIFURCATION OF UNSTABLE INTERFACE BETWEEN FLUIDS IN POROUS MEDIUM

In the paper it is found by a theoretical analysis and numerical experiments that the bifurcation of unstable interface between fluids in porous medium can be determined essentially by the values of dimensionless parameters C1 and 5. For any given C1 there is a critical value S1 of 5 such that when 1 < 5 < S1 the flat interface perturbed by any small disturbance will develop to a long finger without bifurcation. There is a critical value C1* of C1 such that for any given C1 > C1* there are two distinct crit...

1990, 22(5): 526-537. doi: 10.6052/0459-1879-1990-5-1995-981

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PHASE RETARD INTEGRATION METHOD USED IN FLOW BIREFRINGENCE TO ANALYSE THE FLOW WITH A SYMMETRIC PLANE

The formulas which can be used for birefringent medium with a symmetric plane are derived by means of phase retard integration. Axisymmetric problems are studied and some useful formulas are obtained for these cases. As a practical application, the strain rate analyses of flow in a diverging vessel and a converging vessel have been made at the end of this paper

1990, 22(5): 538-546. doi: 10.6052/0459-1879-1990-5-1995-982

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ANALYSIS AND CALCULATION OF A SHOCK TUBE WITH SUCTION

In order to reduce the early contamination of the test gas in a shock tube, caused by reflected and transmitted shock bifurcation, a novel shock tube of utilizing suction through slots in its walls has been investigated in this paper. In the case of suction, the function of the slots is discussed, the calculating methods of the performance parameters are given and the shape of the shock bifurcation due to interaction between the shock wave and boundary layer is described. It has been confirmed by experiment...

1990, 22(5): 547-554. doi: 10.6052/0459-1879-1990-5-1995-983

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ANALYSIS OF THE LARGE DEFLECTION DYNAMIC RESPONSE OF SIMPLY-SUPPORTED CIRCULAR PLATES BY THE "MEMBRANE FACTOR METHOD"

Based on the energy equilibrium, a new procedure called Membrane Factor Method is developed to analyze the dynamic plastic response of plates with deflections in the range where bending moments and membrane forces both are important. The final deflection of a simply-supported circular rigid plastic plate loaded by a uniformly distributed impulse is obtained. In comparison with other approximate solutions, the present method is found to be simplier and the results in better agreement with the corresponding e...

1990, 22(5): 555-565. doi: 10.6052/0459-1879-1990-5-1995-984

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ON THE INVARIANT REPRESENTATION OF SPIN AND ITS APPLICATION IN FINITE DEFORMATION THEORY

Based on the general solution of a kind of linear tensorial equations, the invariant representation of the spin of a symmetric tensor is obtained. This expression is used to study the spin of right and left stretch tensors and to discuss the relations between the different rotation rate of tensors encountered in finite deformation theory. According to the work conjugate principle, a representation of the stress conjugate to Hill's generalized strain is derived. As an important example, the rate of logarithm...

1990, 22(5): 566-573. doi: 10.6052/0459-1879-1990-5-1995-985

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TURNING POINTS IN THIN SHELLS OF REVOLUTION VIBRATION WITH AXISYMMETRIC MODE

The differential equations governing axisymmetric free vibration of thin shells of revolution (except cylindrical and spherical shells) have turning points when the frequency parameter falls in some range. All six uniformly valid and entire asymptotic solutions are obtained in present paper, when the equations have a simple turning point. Those results have not been reported previously in literature.

1990, 22(5): 574-578. doi: 10.6052/0459-1879-1990-5-1995-986

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A CONSISTENT ALGORITHM OF NEWTON ITERATION AND ITS APPLICATION IN PLATE BENDING FINITE ELEMENT ANALYSIS

The reasons in the loss of accuracy and asymptotic rate of quadratic conver-gency of Newton iteration in finite load increments when using classical tangent stiffness matrix methods of elastoplastic finite element analysis are briefly discussed. A consistent algorithm is proposed which preserves the asymptotic rate of quadratic convergency of Newton iteration and holds a first order accuracy and unconditional stability. It is characterized by the path-independent strategy and the consistent elastoplastic ta...

1990, 22(5): 579-588. doi: 10.6052/0459-1879-1990-5-1995-987

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STATISTICAL THEORY OF THERMALLY ACTIVATED FRACTURE

A nonequilibrium statistical theory of thermally activated fracture connecting atomic bond mechanism with the microscopic properties has been constructed The stochastic growth equation of microcrack is given. The microcrack distribution function, fracture probability, reliability, fracture life distribution function and average fracture life have been derived in a unified theory.

1990, 22(5): 589-602. doi: 10.6052/0459-1879-1990-5-1995-988

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ANTITHIXOTROPY OF HIGHLY CONCENTRATECD COAL-WATER SLURRLES

Coal-water slurries (CWS) a boiler fuels represent a new area of research in the coal utilization. They are concentrated suspensions. The knowledge of their rheological behaviour plays an important role in the preparation, storage, pumping and atomization. According to the assumption of a thixotropic fluid as a material of the rate type, and using the experimental method of the equivalent structure, the rheological equation of state and the rate equation of antithixotropic of CWS, are determined in this pap...

1990, 22(5): 603-609. doi: 10.6052/0459-1879-1990-5-1995-989

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THE SECOND ORDER EFFECTS OF THE TORSION ON THE SECONDARY FLOW IN A HELICAL PIPE

A steady incompressible viscous flow in a helical pipe with lowReynolds number (R < 17/ε~(1/ε) ) is investigated by the perturbation method and the usage of helical coordinate system. A second order solution is fully presented. Results show that the torsion of the pipe has turning and deforming effects on the secondary vortices. As Reynolds number increases from, two vortices of the secondary flow turn around a left-right position to an up-down position.

1990, 22(5): 610-618. doi: 10.6052/0459-1879-1990-5-1995-990

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FLOW RESISTANCE OF A CARREAU FLUID THROUGH CORRUGATED TUBE

本文对Carreau流体经波纹管的蠕动流的阻力特性用差分方法作了数值求解。先施行坐标变换,提出一种保证周期性条件的混合迭代法,能较快得到问题的收敛解。流体的物质参数以及流动区域的几何参数对流动阻力特性的影响作了讨论,同时指出了直径均匀的毛管模型作为渗流模型的不足之处。

1990, 22(5): 619-624. doi: 10.6052/0459-1879-1990-5-1995-991

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A MODEL FOR LAMINATED PLATES USED TO CALCULATE SOUND REFLECTION AND TRANSMISSION

A new model for laminated plates is proposed in this paper, which might be used to calculate simultaneously sound reflection and transmission through the plates. Besides, this model satisfies the continuity conditions of the displacements and transverse shearing stresses at the interfaces. At the end some numerical examples are given.

1990, 22(5): 625-629. doi: 10.6052/0459-1879-1990-5-1995-992

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RIGID-BODY JOINT-ELEMENT METHOD AND STABLITY ANALYSIS OF JOINTED ROCK MASSES

The rigid-body joint-element method provided in this paper is a numerical analysis method that idealizes the deformation body as an assemblage of some rigid blocks and deformable thin layers (joint-elements) between the blocks and can be used to solve the movement of the blocks and the deformation and the stress distribution in the layers under various loading conditions. This, method together with a criterion for determining the stability of a rock system can be used successfully to study the stability pro...

1990, 22(5): 630-636. doi: 10.6052/0459-1879-1990-5-1995-993

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QUALITATIVE ANALYSIS OF CONTROLLED MULTI-PENDULUM

The motion of a multi-pendulum is discussed in the present paper as the model of human body with single suspension.The contiguous bodies of the system perform controlled relative motion. The general dynamical equations of the system are derived using the concepts of path vectors and augmented bodies. In the case of plane motion, the phase plane method can be used to analyse the motion qualitatively. The stability of standing and self-excited swing is discussed as example.

1990, 22(5): 637-640. doi: 10.6052/0459-1879-1990-5-1995-994

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1990 Vol. 22, No. 5

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