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中文核心期刊

1997 Vol. 29, No. 1

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A STUDY ON PULSATION OF TWO-DIMENSIONAL CAVITATING FLOW
The unsteady behavior of a two-dimensional cavitating flow around a NACA4412 foil is investigated in a cavitation tunnel by using the high-speed photography. The high speed photographic records show that there is a low frequency pulsating phenomenon caused by the abrupt breakup of cavity. This pulsation of cavitating flow appears significantly in case of the trans-cavitating flow and results in the pseudo-periodic evolution of cavity length and cavity thickness. The frequency characteristics of the low-freq...
1997, 29(1): 1-7. doi: 10.6052/0459-1879-1997-1-1995-189
NUMERICAL STUDY ON VORTEX PATTERNS AND CRITICAL STATE CHARACTERS IN THE WAKE OF A ROTATING CIRCULAR CYLINDER
A hybrid finite difference and vortex method, which is based on domain decomposition and proposed by the authors (1992), is used forcalculating the flow around a rotating circular cylinder at Reynoldsnumber Re=1 000 and the rotation velocity ratio a∈(0.5,3.25) respectively. Some improvments are made in solution process: ahigh order full implicit difference algorithm is adopted, and the Solvers is replaced by a very efficient modified incomplete LU decomposition conjugate gradient method (MILU-CG). The long-...
1997, 29(1): 8-16. doi: 10.6052/0459-1879-1997-1-1995-190
THE EFFECT OF WALL TEMPERATURE ON THE COHERENT STRUCTURE IN WALL TURBULENCE
In this paper, two conditional sampling techniques,VITA and mu-level algorithms were used to investigate the wall temperature influence on turbulence coherent structure in heated wall. ``Grouped'' method proposed by Tiederman et al. was improved, and the advanced ``Grouped'' method was used with VITA and mu-level technique in analizing the effects caused bywall heating on average bursting period. Experiments indicate that the U rms and detected results of conditional sampling method increase, but aver...
1997, 29(1): 17-23. doi: 10.6052/0459-1879-1997-1-1995-191
ON THE DISPUTE WITH REGARD TO VISCOUS LINEAR STABILITY OF COMPRESSIBLE BOUNDARY LAYER FLOW OVER FLAT PLATE
The major dispute between Mack's and Wazzan's results of the linear instability for flat plate boundary layer lies in the effect of free stream Mach number on the viscous instability. In the paper, taking influence of the air thermodynamic properties into account a temporal eigenvalue problem of an adiabatic flat plate is calculated by a collocation technique. The numerical results indicate that the viscosity is only stablizing for the first mode and the second viscous mode is always stable at M=3. It is co...
1997, 29(1): 24-29. doi: 10.6052/0459-1879-1997-1-1995-192
THE INTERFERENCE OF A SIDE CYLINDER ON THE PRESSURE FLUCTUATION OF TWO CYLINDERS IN TANDEM ARRANGEMENT
Three cylinders are arranged as an equilateral triangle, two cylinders are in tandem arrangement, and the third one is by the side of the two cylinders. The pressure fluctuations of these three cylinders has been studied. The fluctuating pressure of rear cylinder are affected more seriously by the side cylinder. The distribution curve is unsymmetrical, it has very strong fluctuating pressure at outer face and the very weak pressure fluctuating at inner side of the rear cylinder. Also, the critical spac...
1997, 29(1): 30-37. doi: 10.6052/0459-1879-1997-1-1995-193
MATRIX CRACK IN A COMPOSITE WITH WEAK INTERFACES
With two-dimensional elastic model,this paper studied the mechanism of the interaction between a matrix crack and weak interfaces in fiber-reinforced composites. The basic solutions of edge dislocations embedded in an anisotropic multi-layered medium were first derived. Then, by using them as kernels,a set of singular integral equations was established for a typical H-shaped defect in weak-interface composites. Finally,the effects of various microstructural parameters, such as interfacial bonding strength,r...
1997, 29(1): 38-46. doi: 10.6052/0459-1879-1997-1-1995-194
THE PROJECTED RELATION OF THE CONSERVATION INTEGRAL IN MICROCRACK SHIELDING PROBLEMS
In this paper, the J integral conservation in adopting the continuum mechanics in the microcrack shielding problems is reexamined. From thetheoretical manipulation as well as the computational experiment, it is proved that there is a redistribution relation of the remote J integral in the microcracking damage region, i.e., the relation of theprojected conservation of the J k vector. In the relation, the J 2 component ignored by Herrmann and Herrmann plays an important role. It is concluded...
1997, 29(1): 47-53. doi: 10.6052/0459-1879-1997-1-1995-195
SPALLING DAMAGE EVOLUTION BEHAVIOR OF SiCp/ZL101Al COMPOSITE
An experimental approach is used to investigate the spalling damage evolution in an Al-alloy reinforced with SiC particles. The microscopic observation and statistic quantitative analysis to the microdamage show that the microdamage occurred at the composite are themicrocracks, including particle cracking and debonding of interface betweenthe particle and matrix. The nucleation and devlopment of the microdamage not only depended on the stress levels and stress duration but also related to the microstructur...
1997, 29(1): 54-61. doi: 10.6052/0459-1879-1997-1-1995-196
THE WEDGE SUBJECTED TO TRACTIONS IN PROPORTION TO r n : A PARADOX OX RESOLVED
The classical solution for the stress distribution in an elastic wedge subjeted to tractions in proportion to r n(n0) becomes infinite when the wedge angle 2α and n satisfy certain relations. This paradox has been resolved by Demsey and Ting when n=0 ,and when n>0 and 2α=π or 2π it has been resolved by Wang Minzhong,however,the researches above provide only a few parts of the resolution for the paradox. In this paper we study all the cases of this paradox by adopting the method...
1997, 29(1): 62-73. doi: 10.6052/0459-1879-1997-1-1995-197
PERIODIC MOTIONS AND ROBUST STABILITY OF THE MULTI-DEGREE-OF-FREEDOM SYSTEMS WITH CLEARANCES
An analysis is presented for determining the dynamical responses for a class of multi degree of freedom systems with clearances or gaps. The systems consist of linear components, but the maximum displacement of one of the masses is limited to a threshold value by a rigid wall. The system is uncoupled by using modal matrix approach. Based on the impacting condition and the matching condition according to the impact law, we have derived the periodic motions and their stability conditions. Then, applying th...
1997, 29(1): 74-83. doi: 10.6052/0459-1879-1997-1-1995-198
ON DYNAMICS OF MULTIBODY SYSTEM DESCRIBED BY FULLY CARTESIAN COORDINATES
The formulation of kinematics and dynamics of multibody system basedon the fully Cartesian coordinates has an important advantage incomputational efficiency. In present paper the analytical expression oflinear and angular momentums of rigid body and multibody system in fullyCartesian coordinates and the coresponding generalized inertia matrix are given. The dynamics of a torque-free multibody system described by the fully Cartesian coordinates in the form of differential equations of first order is formulat...
1997, 29(1): 84-94. doi: 10.6052/0459-1879-1997-1-1995-199
AN ADAPTIVE BLOCK IMPLICIT ALGORITHM FOR INCOMPRESSIBLE FLOW CALCULATION IN COMPLEX GEOMETRY BOUNDARY
By directly coupling the contra-velocities and pressure , ,, p instead of u, v, w, p in a controlled volume in body-fitted coordinates, an adaptive Block Implicit Finite Volume Method (BLIFV) is presented. The drawback of the original BLIFVin solution of incompressible flows within complex geometry boundariesin a staggered grid system is completely eliminated. Good performance is obtained in computing the flow in a 90 。bend. And the calculated results are found in good agreement with the experime...
1997, 29(1): 95-98. doi: 10.6052/0459-1879-1997-1-1995-200
UNITED PROOF FOR QUALITATIVE PROPERTIES OF DISCRETE AND CONTINUOUS SYSTEMS OF VIBRATING ROD AND BEAM
Applying a method of limit transition, we have come to the oscillatory properties of Green's functions of continuous systems from the sign oscillatory properties of stiffness matrices of discrete systems for a vibrating rod or beam.
1997, 29(1): 99-102. doi: 10.6052/0459-1879-1997-1-1995-201
A KIND OF DYNAMICS WITH SNAP BACK REPELLER
By investigating a class of two dimentional mappings reflecting patterndynamics, we found a kind of complex dynamics with two positive Lyapunov exponents. Numberical and analytical discussion show this kind of dynamics may be caused by snap back repeller. More theoretical analysis will be expected in future work.
1997, 29(1): 103-107. doi: 10.6052/0459-1879-1997-1-1995-202
ON THE STABILITY OF A SPINNING, ROTATIONALLY SYMMETRIC TOP CONTAINING LIQUIDS
The problem of coupling between the nutational oscillation of a gyro containing three component liquids and the natural oscillation of the rotating liquids themselves is investigated .The interfacial tension is considered in the free surface bounding the liquids. The linearized equations are treated analytically using the Stewartson's and Zhukovsky's theory . The stability of motion is investigated using the method of residues. It is shown theoretically that instability can occur when any of the perio...
1997, 29(1): 108-110. doi: 10.6052/0459-1879-1997-1-1995-203
ON THE INTEGRAL APPROACH TO CAUCHY'S MEAN ROTATION
This paper presents an integral approch and an analytical expression for computation of Cauchy's mean rotation as a local measure of mean ratation,and answers a difficult question of Truesdell and Toupin's Classical work.
1997, 29(1): 111-115. doi: 10.6052/0459-1879-1997-1-1995-204
LOCAL ARC-LENGTH METHOD——A SOLUTION PROCEDURE FOR NON-LINEAR FINITE ELEMENT METHOD
This paper describes a new solution procedure, the local arc-length method that is a development of the arc-length method and can be used for structures with strain-softening materials. The new procedure is based on using a constraint equation which uses displacement parameters associated with the localized failure zone in such structures. Numerical examples show that this new procedure is more reliable than current versions of the arc-length method. By using this method, not only the ultimate load o...
1997, 29(1): 116-122. doi: 10.6052/0459-1879-1997-1-1995-205
AN ADVANCED METHOD TO CALCULATE THE RESPONSE OF LAYERED HALFSPACE TO ARBITRARY INCIDENT SEISMIC WAVES
In this paper, an efficient analysis method to calculate the response of layered halfspace subjected to arbitrary incident seismic waves is presented in algebraic matrix forms. The method is based on the substructure technique. The interaction between layered soil and halfspace is considered through the relationship between displacement and force at the interface which is solved together with the discrete equations of layered soil. The result shows that the method developed in this paper has the advantage o...
1997, 29(1): 123-127. doi: 10.6052/0459-1879-1997-1-1995-206