力学学报

INTERACTION BETWEEN 3-D VORTICES

The flow field of three dimensional vortex and interaction between vorticeswere measured in detail by using a seven hole probe. The radial distributions of axialvelocity, total and static pressure coefficients through the vortex core were compared fortwo conditions with and without interfering vortex. The mechanism of interaction betweenvortices was discussed.

1994, 26(3): 257-265. doi: 10.6052/0459-1879-1994-3-1995-545

PDF

MORPHOLOGICAL CONFIGURATIONS OF MATERIALELEMENTS DURNG TURBULENT MIXING──EXPERIMENTAL STUDY AND MODELLING

Different morphology of the materials of the Kolmogoroff scale seemsto be the main difference among the several mechanistic models of nncromining. A highspeed microphotography method was employed to investigate the configuration of materialelements of 10￣1-10￣3um during turbulent intong. The microphotographs showed that theelements tend to exhibit slice-like and striplike configurations during mixing. Based onthis evidence a new micromixing model was proposed. The element was modelled by aslab surrounded by...

1994, 26(3): 266-274. doi: 10.6052/0459-1879-1994-3-1995-546

PDF

QUASI-FLOW THEORY OF ELASTIC PLASTIC FINITE DEFORMATION

A Quasi-Flow Theory of elastic plastic finite deformation is proposed. Thetheory originates from the classical normality law. By introducing a weak function withrespect to elastic modulus into the constitutive equations and by improving the commondecomposition scheme of elastic and plaistic strain rates, the Quasi-Flow Theory achieves asmooth and continuous transition from the fiuite deformation Prandtl-Reuss equation (J2F)based on the norrnality law to the rate form of the hypoelastic J2 deformation theory...

1994, 26(3): 275-283. doi: 10.6052/0459-1879-1994-3-1995-547

PDF

A STRIP DAMAGED-PLASTIC ZONE MODEL OF INTERFACE CRACK UNDER TENSION LOADING

A Strip damaged-plaistic zone model of bimaterial interface crack underuniaxial tension loading is proposed in this paper,which is an extension of Dugdale model.It is assumed that the stresses are finite and satisfy the Mises yield condition at the end ofplastic zone,the size of damage zone is proportional to an equivalent crack tip displacementδ=[(CTOD)￣2+(CTSD)￣2]1/2.From these conditions the sizes of damage zone and plasticzone,the normal and tangential cohesive stresses,the CTOD and CTSD can be determin...

1994, 26(3): 284-296. doi: 10.6052/0459-1879-1994-3-1995-548

PDF

THE CHARACTERISTICS OF WAVE PROPAGATION IN A PERIODIC ORIHOGONALLY STIFFENED FLAT PLATE

The characteristics of wave propagation in a periodic plate reinforced byregular orthogonal stiffeners are analyzed using the mutual variational principle. The hi-erarchical finite element method is used to set up the matrix eigen-equation governing thewave propagation problem. The numerical results show that this method can guarantee agood accuracy even in high frequency field.Finally,the effect of the ratio of length to width.the paramaters of the stiffeners and the boyndary conditions are discussed.

1994, 26(3): 297-302. doi: 10.6052/0459-1879-1994-3-1995-549

PDF

A COMPARISON BETWEEN THE DISCRETE LOCAL TRANSMITTING BOUNDARY AND THE SUPERPOSITION BOUNDARY IN WAVE PROPAGATION

The reflection coefficients of the discrete local transmitting bound ary(DLTB)and the superposition boundary(SB)in modeling anti-plane and in-plane wavemotions are studied.The effects of both space and time discretizations on wave motion andthe infiuence of the reflected wave on the coefficients are considered.One-dimensional finiteelement discrete model is adopted in discussing the variation of reflection coefficient withthe order of the corresponding boundary.It is shown that the DLTB is more accurate tha...

1994, 26(3): 303-311. doi: 10.6052/0459-1879-1994-3-1995-550

PDF

BIFURCATION THEORY METHODS IN THE DESIGN OF ANALOG NEURAL NETWORKS

Normal form equations in bifurcation theory are used to design and syn-thesize analog neural networks which can store st at ic or oscillating memory patterns.For the network storing static memory patterns,the normal form equations are of the pitch- fork bifurcation type. If the stored patterns are periodically oscillating, the normal form equations are of the mutiple Hopf bifurcation type. The synaptic weights obtained from the coefficients of the normal form equations which satisfy the designing restraint...

1994, 26(3): 312-319. doi: 10.6052/0459-1879-1994-3-1995-551

PDF

CONSISTENT TANGENT STIFFNESS METHOD AND ITS APPLICATION TO THREE-DIMENSIONAL ELASTOPLASTIC FINITE ELEMENT ANALYSIS

A method,called the Consistent Tangent Stiffness Method (CTSM),isproposed in this paper.we apply CTSM to the solution of three-dimensional elastoplas-tic problems.The method satisfies the complementary criteria of loading and unloading.and furthermore it is characterized by the advantages of preserving the asymptotic rateof quadratic convergency,consuming less computational tinie, holding the first order ac-curacy and unconditional stability.The problems of slow convergence and low accuracy,which have exist...

1994, 26(3): 320-332. doi: 10.6052/0459-1879-1994-3-1995-552

PDF

DYNAMIC ANALYSIS OF CONSTRAINED MULTIBODY SYSTEM WITH COUPLED RIGID AND ELASTIC MOTIONS

A relative coordinate svstem is presented to describe the motion of multi-body systems.This coordinate system fully utilizes the property of translation matrix,sothat the nonlinear couplings between rigid motion and elastic motion are greatly reduced. The equations of planar and spatial deformable body are derived based on finite elemeiitmethod and Lagrange' s equation. Numerical methods for solving the equations are alsodiscussed and the generalized coordinate partitioning method is presented.According tot...

1994, 26(3): 333-340. doi: 10.6052/0459-1879-1994-3-1995-553

PDF

THE APPLICAIONN OF THE METHOD OF “DIVIDING ”TO DYNAMICAL ANALYSIS OF TREE SYSTEMS

In this paper, the chain forms of L-E and N-E have been developedinto tree systems,Concepts of“empty body”and“void road” are introduced.Based onthese concepts,we present the concept of“dividing lane”.This method has a numberof advantages,such as high efficiency, less difficulty for analysis and easiness of computerprogramming,etc. It is an excellent method for dealing with dynamics of tree systems.

1994, 26(3): 341-347. doi: 10.6052/0459-1879-1994-3-1995-554

PDF

MEASUREMENTS AND ANALYSES OF TEMPORALLY AND SPATIALLY RESOLVED SPECTRA OF GRAPHITE PLASMA PLUME INDUCED BY LASER

Measurement results of temporally and spatially resolved spectra ofGraphite plasma plume induced by YAG laser at different energy fluencies(0.2J/cm￣2-300J/cm￣2)are reported. Depending on these results,we have analysed the creation anddevelopment processes of the plume, suggested a dynamic model and obtained the changeof vefocities and number densities of CⅢ,CⅡ and C_2 in the plume.

1994, 26(3): 348-355. doi: 10.6052/0459-1879-1994-3-1995-555

PDF

NUMERICAL SIMULATION OF COAL COMBUSTION IN ANGENTIAL FIRED BOILER FURNACE── CONSTANT DENSITY MODEL OR CONSTANT DIAMETER MODEL FOR THE COAL PARTICLE

The pulverized coal combustion process is simulated numerically in a tangentially fired furnace with either a constant density model or a constant diameter model of the coal particle. The motion and combustion of pulverized coal is described with the concept of the computational particle,The distribution of heat release from combustion is obtained by statistics based on the assumption of normal distribution of pulverized coal mass around the computational particle.

1994, 26(3): 356-367. doi: 10.6052/0459-1879-1994-3-1995-556

PDF

ANANALYSIS ON RADIAL LAMINAR BOUNDABY LAYER DEVELOPMENT FLOW OF POWER-LAW FLUID BETWEEN TWO PARALLEL DISKS

In this paper,B.B. Golubef method is first extended to analyze the laminarboundary layer development flow of power-law fluid between two parallel disks.With theboundary layer motion equation,we have derived both the momentum integral equationand the energy integral equation. Then by solving the momentum integral equation,thedevelopment of the boundary layer in the entrance region and coefficients of the entranceregion effect are analyzed and calculated. Furthermore, the effects of flow-index of power-law fi...

1994, 26(3): 368-373. doi: 10.6052/0459-1879-1994-3-1995-557

PDF

A TRIANGULAR DISPLACEMENT-BASED ELEMENT OF THICK/THIN PLATES

In this paper,a triangular displacement-based element with 9 degrees of freedom for thick/thin plates is developed,and its explicit element stiffness matrix is also presented.This element can obtain high precision with simple formulation for the wide range of plate thicknesses and is free of shear-locking as the thickness of the plate approaches zero.

1994, 26(3): 374-379. doi: 10.6052/0459-1879-1994-3-1995-558

PDF

CONSERVATVE QUANTITIES AND LIE'S SYMMETRIES OF NONCONSERVATIVE DYNAMICAL SYSTEMS

This paper discusses Lie’s symmetry of nonconservative mechanical sys-tems. The existence conditions of conservative quantities corresponding with Lie's symmetryare est ablished. Two illustrative examples are given. Finally, we explain from an examplethat Noether's symmetry may not be Lie's symmetry for nonconservative mechanical system.

1994, 26(3): 380-384. doi: 10.6052/0459-1879-1994-3-1995-559

PDF

1994 Vol. 26, No. 3

NoticeMORE+

Exquisite ArticlesMORE+

Download Center

Author Center