力学学报

AN ANALYTICAL SOLUTION FOR THE MODEL OF DRUG DISTRIBUTION AND ABSORPTION IN SMALL INTESTINE

1991, 23(1) doi: 10.6052/0459-1879-1991-1-1995-807

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OBSERVATION OF FLOW CONFIGURATION IN THE FLOWESTABLISHING ZONE OF THREE-DIMENSIONALBUBBLE PLUME

The flow configuration in flow establishing zone of three-dimensional bubble plume was investigated experimentally. The experiment parameters, methods, device and results are given. Some discussion and conclusions are also given.

1991, 23(1): 1-7. doi: 10.6052/0459-1879-1991-1-1995-802

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BUBBLE COLLAPSE IN SOLID-LIQUID TWO-PHASE FLUID

Equation of motion for bubble collapse in solid-liquid two-phase fluid have been derived, in which the resistance coupling effects between the liquid and solid particles have been considered. The motion of particles during the bubble collapse and the effects of particles on bubble collapse have been calculated and discussed. Qualitative relations between the concentration and the size of the particles and the rate of bubble collapse have been obtained.

1991, 23(1): 8-16. doi: 10.6052/0459-1879-1991-1-1995-803

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ON THE THRESHOLD PROBLEM OF NONLINEAR STABILITYFOR COATING FLOWS

This paper considers the problem of nonlinear stability of a liquid layer flowing down an inclined plane. A perturbation method, which proposed in the application of weakly nonlinear theory to the problem of stability of plane Poiseuille flow by H. Zhou, is now used here in subcritical range. The simplified boundary conditions are given in this paper.The situations for different Reynolds numbers and wave numbers are calculated. The results indicate that when the Renolds number is near the neutral curve, the...

1991, 23(1): 17-24. doi: 10.6052/0459-1879-1991-1-1995-804

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THE INFLUENCE OF TEMPERATURE ON CROSS-HATCHING

The influence of temperature on cross-hatching on cone models made of wax and camphor is studied. Ablating experiments are carried out in heated supersonic tunnels. The relation between temperature and the wavelength of hatching is obtained. The relation between pressure and the wavelength of hatching is verified. The influence of temperature and pressure on the initial position of the appearance of hatching and on the time required for both the appearance of hatching and the formation of stable hatching an...

1991, 23(1): 25-27. doi: 10.6052/0459-1879-1991-1-1995-805

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THE DISTRIBUTION OF SOLID PARTICLES SUSPENDED IN A TURBULENT FLOW: A STOCHASTIC APPROACH

The random motion of solid particles suspended in two-dimentional turbulent flow is considered in this paper. Mean values of partical velocity and displacement in a direction normal to the mean streamlines of the flow are calculated and it is found out that particle velocity vp can be decomposed into a mean velocity (vp) and a velocity fluctuation vp - (vp) where (vp) is equal to the settling velocity of the same particle in tranquil fluid. A Langevin random differential equation for particle displacement Y...

1991, 23(1): 28-36. doi: 10.6052/0459-1879-1991-1-1995-806

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APPLICATION OF PDA AND LDA TECHNIQUES IN MEASUREMENT FOR PHYSICAL CHARACTERISTICS OFBUBBLE-LIQUID FLOW

A Particle Dynamics Analyzer (PDA) is employed to measure the velocity and diameter of bubbles (measurement ranges between 0-5 m/s and 0-15 mm), the liquid velocities in liquid circulation zone and in bubble-water plumes are measured in two dimensions by using a Laser Doppler Anemometry (LDA) technique. It is shown that the diameter of bubbles is almost a constant at different levels in the vessel. The radial distribution of velocity of bubbles and liquid in two-phase plumes is found to be well represented ...

1991, 23(1): 46-52. doi: 10.6052/0459-1879-1991-1-1995-808

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A QUADRILATERAL ELEMENT FOR THIN PLATE BENDING

In this paper, based on the modified potential energy functional and by introducing the generalized conforming conditions, a quadrilateral displacement element for thin plate with 12 degrees of freedom, LGC-Q12, is developed. By use of this element with good compatibility and simple formulations we can obtain higher accurate solution and can pass the patch test approximately if the element shapes are protruding quadrilaterals.

1991, 23(1): 53-60. doi: 10.6052/0459-1879-1991-1-1995-809

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TOUGHNESS INCREMENT BY CRACK GROWTH IN TOUGHENED STRUCTURAL MATERIALS

The toughening due to energy-dissipating crack wake and bridging during crack growth is analyzed in the present paper. According to their contributions to the energy integraJ applicable to a growing crack, the toughening mechanisms for toughened structural materials can be decomposed into: dilitational plasticity and induced shear yielding along the crack wake; bridging due to second inclusion phases; and matrix bridging of a wavy crack front. Detailed toughening analysis is carried out for structural polym...

1991, 23(1): 61-71. doi: 10.6052/0459-1879-1991-1-1995-810

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THE EIGENVALUE PROBLEM OF THE CHAIN OF IDENTICALSUBSTRUCTURES AND THE EXPANSION METHODSOLUTION BASED ON THE EIGENVECTORS

Analytical method to the chain of identical substructures is treated in this paper. The nalysis can also be applied to the semi-analytical method in the mathematical physics, that is to make discretization to the transverse cross section and then solve the differential equations along the longitudinal direction. Two methods are treated concurrently, i.e. the method of shifting invariance and the method of initial parameters and transfer matrices. The mutual relation between these two methods is explained. T...

1991, 23(1): 72-81. doi: 10.6052/0459-1879-1991-1-1995-811

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A NONLINEAR CONSTITUTIVE THEORY FOR MIXTURE OFTWO-PHASE FLUIDS

A nonlinear diffusion theory of two-phase mixture fluids has been discussed under the constitutive principles of continuum mechanics, where one phase is micropolar fluid, another is classical fluid. Both the two components are supposed to be rate-type simple material with second-order complexity for the translation and first-order for the micro-rotation. The general form of constitutive equations for the mixture motion is derived. As special cases, the second-order nonlinear constitutive equations for each ...

1991, 23(1): 82-91. doi: 10.6052/0459-1879-1991-1-1995-812

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THE PROBABILITY DENSITY FUNCTIONS OF THE STATIONARY RESPONSE OF CERTAIN CLASSES OF NONLINEAR SYSTEMS TO STOCHASTIC EXCITATION

In the present paper the nonlinear systems with energy-dependent nonconserva-tive forces are considered. The exact probability density functions of the stationary response of four classes of such systems to white noise external and/or parametric excitations are constructed. The conditions under which the steady-state solution exists are discussed. It is pointed out that all the steady-state solutions available up to now are special cases of the present solutions. Several examples are also given to illustrat...

1991, 23(1): 92-102. doi: 10.6052/0459-1879-1991-1-1995-813

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LOCAL ANALYSIS OF THE BUCKLING AND INITIAL POST-BUCKLING OF THIN-WALLED STRUCTURES AND ITS ACCURACY

为了解决大型复杂薄壁结构稳定性有限元分析中方程阶数过高的问题,本文建议用结构局部代替整体进行计算,证明局部分析方法可以得到整体结构线性分支点的上限和下限,以及整体结构渐近后屈曲行为的近似解,给出了算例。

1991, 23(1): 103-109. doi: 10.6052/0459-1879-1991-1-1995-814

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SIMUTANEOUS MEASUREMENT OF 3-D DISPLACEMENT DERIVATIVES BY SHEARING MOIRE INTERFEROMETRY

A Shearing Moire Interferometry is proposed. 3-D displacement informations are recorded on the same plate by double-exposure method. Carrire introduced to the beams in their first diffraction orders are changed between two exposures. Optical filtering and shearing techniques are applied to extracting the contour maps of 3-D displacement derivatives. Rigorous theoretical analyses are given. Demonstration experiment are conducted successfully and in-plane and out of plane displacement derivatives are obtained...

1991, 23(1): 110-115. doi: 10.6052/0459-1879-1991-1-1995-815

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ON THE ENERGY EQUATION FOR A SPATIALLY DEVELOPING INSTABILITY WAVE IN THE THEORY OF HYDRODYNAMIC STABILITY

In the literatures of theory of hydrodynamic stability, energy equation is often being used. However, the energy equation for a spatial mode problem was always simplified by neglecting a term representing the work done by the pressure. In this article, it was. shown by numerical examples that such a treatment is in general unjustified.

1991, 23(1): 116-118. doi: 10.6052/0459-1879-1991-1-1995-816

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THE CONDITION OF APPLICABILITY OF GENERAL EVOLUTION CRITERION TO THERMO-ELASTIC MATERIALS

In this paper, we study the constitutive restrictions of General Evolution Criterion to thermo-elastic materials and conclude that the sufficient and necessary condition of applicability of General Evolution Criterion to thermoelastical materials is that the mechanical deformation is uncoupled with the heat-condition, therefore, the General Evolution Criterion can not be applied to thermo-elasticity as a general rule.

1991, 23(1): 119-122. doi: 10.6052/0459-1879-1991-1-1995-817

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THE UNIFICATION OF DAMAGE WITH FRACTURE

The shortcomings of damage mechanics foundation are discussed. The new universal statistical damage concept is defined from stochastic evloution of microcracks (microvoi-ds) The kinetic equation of damage-fracture probability is derived. The damage, fracture, statistics, microscopic mechanism and macroscopic properties are connected organically with one another, and the unified microscopic statistical theory of damage fracture is constructed.

1991, 23(1): 123-128. doi: 10.6052/0459-1879-1991-1-1995-818

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