力学学报

IN MEMORY OF PROFESSOR KUO YONGHUI

As a famous scientist specialized in mechanics and applied mathematics, Professor Guo Yonghuai had made an outstanding contribution to gas dynamics and its applications in China. Before his tragic death in an air accident during a working trip in 1968, Guo had been the editor-in-chief of Acta Mechanica Sinica. Under his leadership, the Journal has established and kept up high academic standard, fairness and the truth-seeking spirit.We give here a very brief description of his illustrious life and publish so...

1999, 31(4): 385-388. doi: 10.6052/0459-1879-1999-4-1995-045

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OXV-HYDROGEN COMBUSTION AND DETONATION DRIVEN SHOCK TUBE

The performance of oxy-hydrogen combustion (deflagration) driver ignited by multiple spark plugs distributed along axis direction were analysed and observed. The causes for low quality of test flow produced by the combustion driver have been found. An improved ignition means with three ignitors at main diaphragm has been developed, by which the incident shock waves with repeatability can be produced and the steadiness of the pressure temperature and velocity of the flow behind the incident shock were improv...

1999, 31(4): 389-397. doi: 10.6052/0459-1879-1999-4-1995-046

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PROBLEMS ABOUT GIRD AND HIGH ORDER SCHEMES

In this paper, the relation between the difference scheme and grid system is studied for solving Navier-Stokes equations with given Reynolds number. Only if this relation is satisfied in the directions x, y, z respectively, the Navier-Stokes equations can be simulated properly. In many references solving full Navier-Stokes equations with second order difference scheme, the grids in the direction z normal to the wall airs fine enough since the clustering grid technique is used. The proposed relation is satis...

1999, 31(4): 398-405. doi: 10.6052/0459-1879-1999-4-1995-047

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LARGE-EDDY SIMULATION FOR CANOPY TURBULENT FLOW

The boundary layer theory proposed by L. Prandtl in 1904 has played a tremendously important role for aeronautical and aerospace engineering during the last 100 years or so. Nowadays it has found wide applications both in industry and geophysical flows. The present paper mainly address to the turbulence in Atmospheric boundary layer (ABL) or its surface layer, which is closely related to climate and ecological environment prediction. We have reviewed on its principal numerical approaches: Reynolds average N...

1999, 31(4): 406-415. doi: 10.6052/0459-1879-1999-4-1995-048

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THE OSCILLATORY THERMOCAPILLARY CONVECTION IN A FLOATING ZONE

The convection driven by buoyancy is weaken in microgravity environment. It is possible to obtain a high-quality and large-scale crystal by using floating zone method without pollution and shear from wall of the container in space. The convection driven by surface-tension gradient at the free surface, called as thermocapillary convection, will be dominant in microgravity environment. The half floating zone has been used as one of the models to study thermocapillary convection since the end of 1970s. The exp...

1999, 31(4): 415-422. doi: 10.6052/0459-1879-1999-4-1995-049

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AN ANALYSIS OF COMPACTION WAVE IN GRANULAR MATERIAL

A one-dimensional, two-phase flow model and the intragranular stress function is used to describe the structure and its formation of compaction wave in granular material. The piston impact problem for a compressible porous solid has been solved using a simplified model neglecting gas phase effects. With this model, it is possible to obtain an solution for the compaction wave speed, final porosity, and final pressure. At low piston velocities, the compaction wave travels at speeds less than the ambient solid...

1999, 31(4): 423-433. doi: 10.6052/0459-1879-1999-4-1995-050

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THE STUDY OF REENTRY TURBULENT WAKES AND ITS EFFECTS ON RADAR CROSS SECTION

For analysis of radar cross section (RCS) of hypersonic underdense turbulent ware of reentry vehicles, a theoretical method for calculating the plasma fluctuation intensity is developed based on analysis of the characterization of the hypersonic wake flow. In the method k-ε-g turbulent model is adopted to complete Reynolds equation, in which the chemical component fluctuation intensity is taken into account. The governing equations are solved by fully implicit finite-difference schemes. For calculating RCS,...

1999, 31(4): 434-441. doi: 10.6052/0459-1879-1999-4-1995-051

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RESEARCH ON THE DEFORMATION, DAMAGE AND FRACTURE RRLES OF CIRCULAR TUBES UNDER INSIDE-EXPLOSIVE LOADING

1999, 31(4): 442-449. doi: 10.6052/0459-1879-1999-4-1995-052

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EXPERIMENTAL TESTS AND NUMERICAL CALCULATIONS FOR THE 37 mm RAM ACCELERATOR

The first ram accelerator in the country, 37mm ram accelerator, has been built atCARDC. In this paper, the working principle and worldwide reseaxch situation of ram accelerator are introduced at first, followed by the description of the main sub-systems of this 37mm ram accelerator, typical shot test results, and some pertinent CFD work.

1999, 31(4): 450-455. doi: 10.6052/0459-1879-1999-4-1995-053

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EXPERIMENTAL INVESTIGATION ON INTERACTIONS BETWEEN PHASES IN GAS-SOLID HORIZONTAL BOUNDARY LAYER

In this paper the interactions between air flow and particles have been investigated with a three dimensional particle dynamics analyzer (PDA) for the gas-solid two-phase flow in a horizontal boundary layer. The mean velocity and the statistics of turbulence fluctuations for both phases in the steamwise and the vertical direction were obtained simultaneously. Effects of particles with nominal diameter of 230μm at two different particle mass loading ratio, 1.8%and 24%, on the air flow boundary layer were exa...

1999, 31(4): 456-465. doi: 10.6052/0459-1879-1999-4-1995-054

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A THEOREM OF UPPER AND LOWER BOUNDS ON EIGENVXLUES FOR STRUCTURES WITH BOUNDED TRIMETERS

In structural dynamics, generally we can not determinate accurately the natural frequencies and eigenvalues due to various approximations. But we may obtain an eigenvalue interval, where the lower bound eigenvalue can be determinated by, say, Dunkerly's or Temple's method; the upper bound eigenvalue can be computed by multi-term Rayleigh-Ritz or Galerkin method. Alternatively, the upper and lower bounds and can be obtained simultaneously by means of Hu Haichang's "Mass Inclusion Theorem and Rigidity Inc...

1999, 31(4): 466-474. doi: 10.6052/0459-1879-1999-4-1995-055

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THE OVERALL ELASTIC MODULI AND DAMAGE OF THE MATERALS CONTAINING ORTHOGONAL INCLUSIONS AND DEFECTS

The effective elastic moduli and damage of materials containing orthogonal inclusions or defects are investigated in this paper. Based on Eshelby-Mori-Tanaka's theory, a simplified formula of the effective moduli for a multiphase, anisotropic composite is developed. The explicit expressions of the effective elastic compliance tensor of an orthotropic composite reinforced by three mutually perpendicular families of ellipsoidal inclusions are then derived. These expressions contain the micro-structural parame...

1999, 31(4): 475-483. doi: 10.6052/0459-1879-1999-4-1995-056

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A CONSTITUTIVE MODEL FOR NONPROPORTIONAL CYCLIC PLASTICITY WITH LOADINGPATH DEPENDENCE

In order to describe the hardening behavior of metallic materials under nonpropertional cyclic loading, a number of nonproportionality parameters have been proposed[10]. For some loading paths, the degree of nonpropertional cyclic hardening can be animated by these parameters. But for the paths containing not only the stress relaxation but also the many times unloading per cycle, they do not work well. For instance, these parameters always predicted a higher stress level for the stair-step loading and a low...

1999, 31(4): 484-492. doi: 10.6052/0459-1879-1999-4-1995-057

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MAXIMAL COCK TIP SHIELDING BY MICROCRACKING IN ISOTROPIC ELASTIC SOLIDS

In Hutchinson's (1987) opinion, there are two sources of microcrack shielding, one is the reduction in the effective elastic moduli resulting from microcracking and the other is the strain arising from the release of residual stresses when micro-cracks are formed. This residual stresses in question develop in the fabrication of polycrystalline or multi-phase materials due to thermal mismatches between phases or thermal anisotropies of the single crystals. In this paper, besides the two sources of the redi...

1999, 31(4): 493-497. doi: 10.6052/0459-1879-1999-4-1995-058

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THE CREEP LINE-SPRING MODEL FOR CREEP ANALYSIS OF SURFACE CRACKS

Considering the difficulty of creep analysis of the three-dimensional cracks by the common numerical methods, this paper proposes a creep line-spring method (CLSM) for the estimates of creep fracture parameters for the creep surface cracks. The fundamental equations of the creep line-spring method are established on the bases of the approximate solutions of the non-steady creep crack and the elastic-plastic line-spring method. Several numerical examples for the creep fracture parameters, J and C integrals, ...

1999, 31(4): 498-503. doi: 10.6052/0459-1879-1999-4-1995-059

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DISCUSSION ABOUT THE SCALAR INVARIANTS OF REPRESENTATION THEORY FOR TENSOR FUNCTIONS

It is found that the complete and irreducible scalar invariants in references [1] and [2] are not independent to each other. The scalax invariants of an arbitrary second order tensor and two symmetric second order tensors are studied separately. It is proved that for the previous case there are only six independent scalax invariants and for the later case there are only nine independent scalar invariants.

1999, 31(4): 503-509. doi: 10.6052/0459-1879-1999-4-1995-060

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1999, 31(4): 510-511. doi: 10.6052/0459-1879-1999-4-1995-061

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1999 Vol. 31, No. 4

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