力学学报

Experimental investigation of the bursting characteristics under sheared air-water interface

2005, 37(2): 129-134. doi: 10.6052/0459-1879-2005-2-2003-038

PDF

Experimental study on flow characteristics of a slot jet impingement on semi-circular surface

2005, 37(2): 135-140. doi: 10.6052/0459-1879-2005-2-2003-465

PDF

Wave interaction with arrays of combined cylinders with an solid interior column and a porous exterior column

2005, 37(2): 141-147. doi: 10.6052/0459-1879-2005-2-2004-023

PDF

The research of plume dispersion in the atmosphere boundary layer

2005, 37(2): 148-156. doi: 10.6052/0459-1879-2005-2-2004-187

PDF

A global convergence method on inverse design of transonic airfoil

, Guowei Yang

2005, 37(2): 157-163. doi: 10.6052/0459-1879-2005-2-2004-300

PDF

Lattice boltzmann method for simulating the displacement of deformable membrane in fluid

A lattice Boltzmann method is employed to simulate theinteraction between the deformable membraneand surrounding fluids. The boundary condition and the force exerting on themembrane are handled based on the lattice Boltzmann method. Interactionbetween the membrane and surrounding fluids may cause the membrane tovibrate. The membrane is discretized into segments. Each segment issimplified to a mass particle and connected to its neighbors. The Newtoniandynamic simulation is applied to each segment. The dynamic equation of thedeformable membrane can be simulated according to the force acting on it.The hydrodynamic forces acting on the membrane are obtained by thecomputation of fluid flow stress at the moving boundary using the latticeBoltzmann momentum-exchange method. It can simulate the curved shape withsecond-order accuracy. The fluid flow and membrane deformable equations arecoupled. The membrane as a moving boundary affects the fluid flow, and thedeformation of the membrane is the result of the hydrodynamic force actingon it. In this paper, the configurations of membranes at corresponding timeunder different conditions are computed. In the numerical test, both ends ofthe membrane are fixed and its initial shape is set to be a straight line,its initial vibrant velocity normal to the membrane surface is given to bevaried at different position. The flow is simulated by the lattice Boltzmannmethod with second-order accuracy, and the deformation of the membrane iscomputed using the Newtonian dynamic equation. The results show that theconfiguration of the membrane is closed to its initial straight line in asufficient long time if the membrane is relatively soft or stiff, and theresults agree well with the other published results.

2005, 37(2): 164-168. doi: 10.6052/0459-1879-2005-2-2004-205

PDF

Two kinds of contact problems in decagonal quasicrystalline materials of point group 10mm

By means of the complex variable method, thisinvestigation addresses two kinds of contact problems in decagonalquasicrystalline materials. One kind of contact problem is the frictionalcontact problem, the other one is the adhesive contact problem.Particularly, the explicit expressions of the analytic functionscharacterizing the phonon and phason fields as well as the contact stressdistribution on the indenter are obtained for a flat indenter on a decagonalquasicrystalline half-space. The results show that 1) the contact stressesexhibit the real power type singularities $ - 1/2\pm \beta$ in the edge of the contact zone for the frictional contact problem with $\beta $ determined bythe material constants of the quasicrystal and the static frictional factor;and 2) the contact stresses exhibit the oscillatory singularities $ -1/2 \pm {\rm i} \v$ in the edge of the contact zone for the adhesivecontact problem with $\varepsilon $ determined by the material constants ofthe quasicrystal.

2005, 37(2): 169-174. doi: 10.6052/0459-1879-2005-2-2004-184

PDF

On the complex potentials for a body with holes in doubly periodic plane

First, the complex variable method in planethermoelasticity for harmonic temperature change field is discussed, and thegeneral expression of the complex potentials in a finite multi-connectedregion under harmonic temperature change is derived. Then, based on theanalysis for the expression and multivalue property of the doubly-periodicanalytic function (the real part of which is given) and its object function,the general expression of the two complex potentials in plane elasticity fora body with a doubly periodic set of holes under doubly-periodic harmonictemperature change is obtained. Finally, the conclusion that the heatstresses vanish in two special cases is deduced.

2005, 37(2): 175-182. doi: 10.6052/0459-1879-2005-2-2003-502

PDF

The dynamic analysis of piezoelectric bending actuator considering nonlinear piezoelectric effect

In this paper, nonlinear dynamic characteristics ofpiezoelectric bending actuators under strong electric field are studied.Considering nonlinear piezoelectric effect of the electrostriction andelectroelasticity, the bending vibration governing equation of thecantilever piezoelectric actuator, in which the stiffness is variable withtime, is obtained. Using the asymptotic theory of nonstationary vibrations,the dynamic characteristics of the cantilever actuator are discussed. Theproposed nonlinear model predicts the change in fundamental resonantfrequency of piezoelectric cantilever with the variation in electric field.The predicted resonance amplitude of the tip deflections of thepiezoelectric actuators, which increase with the increase in the magnitudeof the electric field, the decrease in the mechanical quality factor withthe increase in the electric field, and well agrees with experimentalresults. By comparing with predicted results, it is found that the problemof nonstationary vibration can be approximately treated as stationaryvibration under the electric field frequency varies very slowly.

2005, 37(2): 183-189. doi: 10.6052/0459-1879-2005-2-2004-010

PDF

The improvement for the ICM method of structural topology optimization

2005, 37(2): 190-198. doi: 10.6052/0459-1879-2005-2-2004-286

PDF

Three dimensional large amplitude liquid sloshing under pitching excitation

Three dimensional large amplitude liquid sloshing in acyliindrical open tank under pitching excitation is studied in this paper.Firstly, the kinematics of the ALE description is introduced and the fluiddynamics equations are revised in the ALE form. The numerical discretedequations of fractional steps finite element method are developed byGalerkin weighted residual method. Lastly, the numerical simulation of largeamplitude sloshing of the liquid in cylindrical tank is carried out. Thecomputed water elevation history, the computed sloshing force history, thecomputed sloshing moment history and the computed free surface in differenttime are obtained. Numerical results are also analyzed in this paper.

2005, 37(2): 199-203. doi: 10.6052/0459-1879-2005-2-2004-250

PDF

Theoretical frame for unsaturated freezing soil

Soil freezing involves complex processes of a multi-phaseporous medium and interactions with water, heat and deformation. The basictheoretical frame of the multi-phase porous medium is established in thispaper in order to mathematically predict the complex freezing or thawingprocesses for cold region engineering problems. Based on the authors'theoretical frame work of the saturated freezing soil, this paper focuses ona four-phase unsaturated porous medium consisting of soil particle, ice,water and air. Further consideration of the air phase in the unsaturatedfreezing soil is discussed in this paper for two ideal situations: air inthe soil is linked to the outside (the open porous medium), and air in thesoil is sealed from the outside (the sealed porous medium). Thecorresponding theoretical frame work for a multi-phase porous medium withinteraction of water, heat and deformation is proposed in this paper. Theproposed theoretical model is then extended to the general case (unsaturatedhalf-open and half-sealed porous medium), and a proper theoretical model forthe heat-moisture-deformation coupling behavior of the unsaturated freezingsoil is developed. And the software 3G2001 is also developed for theheat-moisture-deformation coupling behaviors. In-site measurements resultsfor Hua Shixia highway roadbed are introduced to compare to the numericalresults of the proposed model. The results indicate that numerical resultsof the temperature field variations along the roadbed depth at differenttime are with very good correlation to the measurements, and so do numericalresults of the relatively freezing deformations of road surface. Bothnumerical accuracy to the measurements are within 10$\sim $20{\%}. Thecomparison analysis shows the proposed theoretical frame and its numericalmodeling for the temperature--moisture deformation coupling behaviors issuitable and acceptable.

2005, 37(2): 204-214. doi: 10.6052/0459-1879-2005-2-2003-039

PDF

The non-axisymmetical dynamic response of layered transversely isotropic saturated soils

The dynamic response of layered saturated soils to anarbitrary buried source is useful and important in seismology, seismicengineering, soil mechanics, geophysics, dynamic foundation theory and soon. Therefore, after Biot putting forward the general wave equations inisotropic saturated porous medium, there are a series of work on dynamicresponse in such medium by the FEM, BEM(in frequency space or Laplacespace), as well as analytical method(completed by Fourier expanding andHankel integral transformation). However, the most researches focus on theisotropic saturated porous medium less involving in anisotropic medium andexisting the limitations among the work mentioned above: the FEM relating toenormous amount of calculation as well as complex artificial boundary, theBEM involving in the completed dynamic singular close solution, which ishard to attain in layered saturated porous medium. Although the analyticalexpression in dynamic stiffness matrix containing $8(N+1)$ pendingcoefficients is given in Ref.[10], it is an onerous work for computing$N$-layers saturated soils.The purpose of this article is to study the non-axisymmetical dynamicresponse of layered transversely isotropic saturated soils under anarbitrary buried source. In the first part, based on Biot's theoryfor fluid-saturated porous media, the 3-D wave equations in cylindricalcoordinate for transversely isotropic saturated poroelastic media aretransformed into the 1-order governing differential equations completed bythe Fourier expanding with respect to azimuth. Then, transfer matrixeswithin layered media are derived by introducing combined state vector andHankel integral transformation. The second part gives the analyticalexpression in dynamic response for multilayered such medium using transfermatrixes followed by boundary conditions and continuity conditions as wellas drainage conditions. In the third part, some numerical results arelisted. Time-domain results may obtain by Fourier synthesis over frequency.

2005, 37(2): 215-224. doi: 10.6052/0459-1879-2005-2-2003-533

PDF

A nonlinear method to determine the wall shear stress in the straight artery in vivo

With the aid of Ling and Atabek's ``local flow''assumption for the nonlinear convective acceleration terms of theNavier-Stokes equation governing the pulsatile blood flow in large arteries,a nonlinear method to determine the wall shear stress in straight arterieswas proposed by use of the measured blood viscosity, center-line velocity,blood pressure and arterial radius. Comparing with the results from thelinear method proposed by Liu Zhaorong et al., where the wall shear stresswas calculated using the measured blood viscosity, center-line velocity andaverage arterial radius, the results from the nonlinear method demonstratedthat, no obvious difference exists between the pressure gradients, thevelocity profiles, and the wall shear stresses calculated from the twodifferent methods when the wall motion ($\d R/R = 2.4{\%}$) is small, however,an obvious difference occurs when the wall motion is large ($\d R/R=12{\%}$).It was concluded that the linear method has high accuracy when the wallmotion is small but the nonlinear effects on the wall shear stress must betaken into consideration when the wall motion becomes large. Because theinputs such as the blood viscosity, the center-line velocity, the bloodpressure and the arterial radius could be measured by use of non-invasiveand/or micro-invasive methods, the nonlinear method provided the methodologybase for the in vivo and/or ex-vivo study of the relationshipbetween the wall shear stress and arterial remodeling.

2005, 37(2): 225-231. doi: 10.6052/0459-1879-2005-2-2003-368

PDF

Experimental investigation of thermocapillary migration of two drops

Experiments were performed on the migration andinteraction of two drops under the action of an applied temperature gradienton the ground. Pure soybean oil and silicon oil were used as continuousmedium and as experimental medium in drops respectively. Images of theseexperiments were recorded and later analyzed to obtain data on thetrajectories and velocities of two drops. The results demonstrate that theeffect of the larger drop on the motion of the smaller one becomessignificant with the two drops approaching each other, while the effect ofthe smaller one on the larger remains weak. And the oscillation phenomenonof migration velocities of both drops is found during the approach. Even thesmaller one moves backwards in a short time when two drops migrate side byside. They display the congruence and difference between the experimentalresults and numerical simulations.

2005, 37(2): 232-237. doi: 10.6052/0459-1879-2005-2-2004-186

PDF

Application of the lattice bhatnagar- gross- krook model to the simulation of seismic pressure wave

In this paper, we propose a new lattice Boltzmann modelfor simulating the seismic pressure wave. By usingChapman-Enskog expansion and multi-scales technique, we obtained a serieslattice Boltzmann equations and conservation law in the time scale $t_0 $. Weselect simple equilibrium distribution functions to get moments for thepressure wave equations. Numerical simulations show this method can be usedto compute seismic pressure wave.

2005, 37(2): 238-243. doi: 10.6052/0459-1879-2005-2-2004-194

PDF

Research for the influence of thickness on the energy distribution of splitting and curling circular steel tube

This paper reports the experimental studies and theoreticalanalyses on axial splitting and curling of A3 steel tubes with differentthickness on a conical die. Seven groups of metal circular tubes, withdiameter $D=54.4$\,mm, are used as the text specimens. The force-compressioncurves and deformation modes of specimens are recorded. Three energydissipation mechanisms are involved: tearing energy, plastic bending energyand friction energy during the specimens deformation. Theoretical analysesfind that the influence of tube-thickness on the ratios of tearing energy andthe plastic energy to the total energy is considerable and on the ratio offrictional energy to the total energy is slight.

2005, 37(2): 244-248. doi: 10.6052/0459-1879-2005-2-2003-470

PDF

The propagation of generalized rayleigh waves in a coated material

Based on the linear elastodynamics theory, an analyticalmodel is established for the propagation of generalized Rayleigh waves in acoated structure. Moreover, the dispersion equation is derived from the wavemotion equations and the boundary conditions. The theoretical solutions ofthe phase velocity are obtained for the cases of different ratios of thecoating thickness to the wavelength, and different density ratios of thecoating to the substrate, by considering respectively the influence of lowlayers and fast layers on the phase velocity. In the numerical examples, thephase velocities, group velocities and the attenuating amplitudes ofdisplacement and stress component in a slow layer structure are comparedwith those in a fast layer structure. Besides, the model and the analysisare validated by comparing with those in the references. This paper providesa theoretical basis to determine the material parameters of various coatingmedia by means of surface wave method.

2005, 37(2): 249-256. doi: 10.6052/0459-1879-2005-2-2004-345

PDF

2005 Vol. 37, No. 2

NoticeMORE+

Exquisite ArticlesMORE+

Download Center

Author Center