力学学报

NUMERICAL INVESTIGATION OF THE AXISYMMETRIC INTERACTION BETWEEN COMPRESSIBLE STREAMWISE VORTICES AND SHOCKWAVES 1)

Numerical results on the interaction between the compressible streamwise vortices and shockwaves were presented in this paper.Two cases were discussed including a moving shockwave interacting with a vortex and a Mach disc at the exit of an overexpanded nozzle interacting with the vortex in the swirling jet. The quasi axisymmetric N S equation was used and the time accurate finite difference TVD scheme was implemented. Compared with the corresponding experiments, the numerical simulat...

1999, 31(3): 257-267. doi: 10.6052/0459-1879-1999-3-1995-030

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EFFECT OF THE WALL INJECTION ON THE SLIP BOUNDARY CONDITIONS 1)

In this paper, the slip boundary conditions with wall injection are discussed. From analysis of mass, momentum and energy flux balance equations at inner and outer edges of the Knudsen layer using the Chapman Enskog velocity distribution function, the system of slip boundary equations with wall injection and catalysis in a multicomponent gas mixture is derived in a general form. Numerical calculations are made for a hypersonic flow passing the stagnation region of a blunt body by using the Viscous Shock La...

1999, 31(3): 268-275. doi: 10.6052/0459-1879-1999-3-1995-031

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A PARALELL ANALYSIS METHOD FOR FULL COUPLED MULTIPHACE FLOW 1)

In this paper, we consider a full coupled multi phase problem involving heat and mass transfer in deforming porous media. The mathematical model consists of balance equations of mass, linear momentum and energy and of the appropriate constitutive equations. The chosen macroscopic field variables are temperature, capillary pressure, gas pressure and displacement. The gas phase is considered to be an ideal gas composed of dry air and vapour, which are regarded as two miscible species. The model makes further...

1999, 31(3): 276-284. doi: 10.6052/0459-1879-1999-3-1995-032

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ANALYSIS OF INTERFACE CRACKS AT A FIBER END 1)

Based on the general solution of the elastic spatial axisymmetric problem, the stress singularities at the tips of the axisymmetric coin and cylindrical interface cracks at a fiber end in short fiber reinforced composites are analyzed and singular stress fields near the tips of the interface cracks are obtained. The results in this paper show that the stress singularities of the axisymmetric coin and cylindrical interface cracks at a fiber end are the same and they coincide with those of the corresponding c...

1999, 31(3): 285-291. doi: 10.6052/0459-1879-1999-3-1995-033

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SCATTERING OF SH WAVE BY CRACKS ORIGINATING AT A CIRCULAR HOLE EDGE AND DYNAMIC STRESS INTENSITY FACTOR 1)

In the category of elastodynamic fracture, the present paper investigates the problem of SH-wave scattering by cracks of any limited lengths originating at the boundary of a cylindrical hole, and gives the solutions of dynamic stress intensify factor at the crack tip. The Green's Function method is used. That means a special Green's function, which is a fundamental solution of displacement field for an elastic half space possessing a half cylindrical gap while bearing out of plane harmonic line source for...

1999, 31(3): 292-299. doi: 10.6052/0459-1879-1999-3-1995-034

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A STUDY OF DAMAGE MECHANICS THEORY IN FRACTIONAL DIMENSIONAL SPACE 1)

Of most importance in continuum damage mechanics is how to properly define a damage variable that is available for describing damage degree and its evolution. It plays a key role in correlating macro mechanical responses to their internal micro/meso damage effects in materials. As one of widely accepted effective approaches to define a damage variable, macro phenomenological definition performs a great advantage of being easily utilized in analyzing macro damage mechanical responses of materials and struct...

1999, 31(3): 300-310. doi: 10.6052/0459-1879-1999-3-1995-035

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ANALYSIS OF STRIP ELECTRIC SATURATION MODEL OF CRACK PROBLEM IN PIEZOELECTRIC MATERIALS 1)

This paper presents a fully anisotropic analysis of strip electric saturation model proposed by Gao, Zhang and Tong for piezoelectric materials. A complete exact solution is obtained for a single crack in an infinite pizoelectric media. The relationship between the size of the strip saturation zone ahead of a crack tip and the applied electric field is established. It is found that the size of the strip saturation zone ahead of a crack tip is independent of the applied stress. The explicit formula for...

1999, 31(3): 311-319. doi: 10.6052/0459-1879-1999-3-1995-036

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STRIP DISTRIBUTED TRANSFER FUNCTION METHOD FOR ANALYSIS OF ELASTIC THIN PLATES 1)

A refined strip distributed transfer function method is presented for the analysis of elastic thin plates. In the analysis, a rectangular plate (substructure) is divided into strips by lines named nodal lines. The displacement functions defined on the nodal lines are one dimensional functions of the nodal line coordinate. Both ends of the nodal line are called nodes. To cope with complex boundary conditions, nodes are also defined on the boundary nodal lines, and the displacement of each strip is interpola...

1999, 31(3): 320-329. doi: 10.6052/0459-1879-1999-3-1995-037

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EFFECTIVE ELECTROELASTIC PROPERTIES OF POLYCRYSTALLINE FERROELECTRIC CERAMICS 1)

As increasing applications of the ferroelectric ceramics in the field of engineering, how to predict their effective electroelastic properties and improve the reliability of their structure becomes more and more important. As we all know, below the Curie temperature, the ferrolectric ceramics have special microstructure domain and one grain may be composed of many domains. Under the action of external field, the particular domain switching, which has two types of mechanism nucleation and domain wall moti...

1999, 31(3): 330-338. doi: 10.6052/0459-1879-1999-3-1995-038

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MULTI POSITION TRANSVERSE IMPACT DAMAGE DETERMINATION WITHIN COMPOSITE LAMINATES BY FIBRE OPTIC IMAGE RECONSTRUCTIONS 1)

By now the multi model fibre optic network embedded in composite laminates for damage detection in which fibre optic bundles are arranged in quadrature or in one direction can only qualitatively show the approximate range of damage. In order to display structural damages accurately and quantitatively, we draw into the concept of reconstruction, as well as the fibre optic damage image processing method, to form a new algorithm for the multi places damage determination within composite laminates. The fibr...

1999, 31(3): 339-346. doi: 10.6052/0459-1879-1999-3-1995-039

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THE CANONICAL HAMILTONIAN REPRESENTATIONS IN A CLASS OF PARTIAL DIFFERENTIAL EQUATION 1)

The infinite dimensional Hamiltonian system plays a very important role in mechanics, but many partial differential equations that appeared from concrete problems are not in the forms of infinite dimensional Hamiltonian system. Therefore, in recent years, many people are concerned about the problem of which partial differential equation, especially, the linear partial differential equations with variable coefficients and nonlinear partial differential equations can be transformed into the infinite dimension...

1999, 31(3): 347-357. doi: 10.6052/0459-1879-1999-3-1995-040

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AN ANALYSIS OF LINE SINGULARITY FOR A 3 D MATRIX CRACK TERMINATING THE INTERFACE VERTICALLY 1)

With the wide use of composite materials,the interface fracture mechanics has received specific attentions. During the past few years,a lot of considerable researches have been carried out and many questions regarding the interface fracture mechanics have been answered . Such as the edge crack terminating at and crossing the interface, the T shaped crack consisting of a broken layer and a delamination crack, the cross shaped crack which consists of delamination crack intersecting a crack which is perpendi...

1999, 31(3): 358-365. doi: 10.6052/0459-1879-1999-3-1995-041

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ACTIVE CONTROL OF PIEZOELECTRIC INTELLIGENT ANNULAR PLATES 1)

In recent years, piezoelectric intelligent materials have been widely used as sensors and actuators in structural shape control, vibration control, etc. It has wide and active field in research and application. The structures with large sized, low stiffness and flexibility are important characteristics in space flight industry. But, because modal damping of the structure is small, when an outside shock force or interference force acts to the structure, it will cause much large deformation and vibration of...

1999, 31(3): 366-371. doi: 10.6052/0459-1879-1999-3-1995-042

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COHESIVE INTERFACE ELEMENT AND INTERFACIAL DAMAGE ANALYSIS OF COMPOSITES 1)

An interface element based on the cohesive zone model is employed to simulate the fiber/matrix interface in composite. The cohesive zone model used here is viewed as a phenomenological model. A potential function is adopted to describe the relationship between the interface traction and the interface displacement jump. Two sets of interface parameters are adopted to represent the interface strength and toughness respectively. This model can simulate the evolution of interface damages, which are coupled in t...

1999, 31(3): 372-377. doi: 10.6052/0459-1879-1999-3-1995-043

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MIGRATION AND INTERACTION OF MULTICOMPONENT CHROMATOGRAPHIC WAVES WITH REVERSIBLE REACTIONS 1)

A general reactive chromatography model including percolation, adsorption, diffusion and reversible reactions was solved by use of the spatial movement analysis and Gram Charlier expansion. Particular attention was paid to the effect of adsorption on migration and evolution of each chromatographic peak, which was inadequately considered in previous literatures. By Fourier transformation, the original model of PDEs is reduced to the ODEs of the spatial movements of concentrations. Analytical expressions for...

1999, 31(3): 378-384. doi: 10.6052/0459-1879-1999-3-1995-044

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1999 Vol. 31, No. 3

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