共查询到20条相似文献,搜索用时 15 毫秒
1.
Jian-Fei Lu Bin Xu Jian-Hua Wang 《International Journal of Solids and Structures》2009,46(21):3771-3781
A numerical model is developed to analyse the isolation of moving-load induced vibrations using pile rows embedded in a layered poroelastic half-space. Based on Biot’s theory and the transmission and reflection matrices (TRM) method, the free wave field solution for a moving load applied on the surface of a layered poroelastic half-space and the fundamental solution for an harmonic circular patch load are determined. Using Muki and Sternberg’s method, the second kind of frequency domain Fredholm integral equations for the dynamic interaction between pile rows and the layered poroelastic half-space are derived. The time domain solution is recovered via inverse Fourier transform in order to obtain the amplitude reduction ratio and thus assess the vibration isolation efficiency of pile rows. A special case of the present model shows good agreement with an existing solution. Numerical results of this study show that the speed of moving loads has an important influence on the isolation of vibrations by pile rows: the same pile rows can achieve better isolation efficiencies for higher speed loads than for lower speed loads. Pile rows embedded in a two-layered poroelastic half-space with a softer overlying layer usually generate better vibration isolation effects than those with a stiffer overlying layer. Finally, better isolation vibration may be realized by increasing the pile length and decreasing the net spacing between neighboring piles in a pile row. 相似文献
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Bin Xu Jian-Fei Lu Jian-Hua Wang 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(2):123-142
The isolation of the vibration due to harmonic Rayleigh waves using pile rows embedded in a saturated poroelastic half-space
is investigated in this study. Based on Biot’s theory and the potential function method, the free field solution for Rayleigh
waves along the surface of the poroelastic half-space is derived first. The fundamental solution for a harmonic circular patch
load applied in the poroelastic half-space are obtained in terms of Biot’s theory and the integral transform method. Using
Muki’s method and the fundamental solution for the circular patch load as well as the Rayleigh waves solution for the poroelastic
half-space, the second kind of Fredholm integral equations in the frequency domain for pile rows are derived. Numerical solution
of the integral equations yields the dynamic response of the pile–soil system to incident Rayleigh waves. Influences of various
parameters on the vibration isolation effect of piles rows are investigated numerically. Numerical results suggest that for
the same vibration source, the same pile rows will produce a better vibration isolation effect for the poroelastic medium
than for a single phase elastic medium. Also, stiffer piles tend to have better vibration isolation effect than flexible piles.
Moreover, the pile length and the spacing between neighboring piles in each pile row have significant influence on the vibration
isolation effect of pile rows. 相似文献
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Nonlinear Dynamics - Most existing quasi-zero stiffness (QZS) isolators with excellent vibration isolation performance in the low-frequency range are designed to attenuate vibration transmission... 相似文献
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In this paper the functionu=rsin in cylindrical coordinates (r,,z) is introduced into the equation for free torsional vibration of bodies of revolution (where=v / r represents the angle of twist). With the static fundamental solution (–1 /R) a mixed BEM / FEM equation is derived. The domain integral term in the equation is discretized by Serendipity elements instead of commonly used constant value finite elements in the literature. The equation is an algebraic eigenvalue one. The dynamic fundamental solution (e
1R
/R) is also used for deriving the other mixed BEM / FEM equation. An appropriate iterative solution procedure is described. An algebraic eigenvalue equation can be obtained and its solution accuracy is almost interior meshing independent. A number of examples are studied. The results show the good economy and high accuracy of the algorithms proposed.The Project is Supported by National Natural Science Foundation of China. 相似文献
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A three-dimensional second-order closure dispersion model is used to simulate the plume behaviour of a passive contaminant in a convective boundary layer. A time-splitting finite element method together with a non-linear filtering scheme is used to solve the three-dimensional second-order closure transport equations. The model results show good agreement with laboratory data for a ground level source. 相似文献
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《International Journal of Solids and Structures》1999,36(24):3617-3638
This paper proposes and discusses a boundary element formulation for a particular class of non-local damage models. The formulation as well as the boundary element computational code developed during this research have proven to be very simple and efficient, providing reliable information on the strains and stresses in damage-softening models. The numerical approach uses a finite-grid to estimate the damage values. Some illustrative numerical examples, which show the simplicity and versatility of the proposed approach, are included and discussed in detail. 相似文献
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M. M. Alimov 《Fluid Dynamics》2013,48(6):800-810
New exact solutions to an idealized single-phase unsteady Hele-Shaw problem of the evolution of the air-viscous fluid interface are constructed for the case when the fluid occupies a half-space type domain in an unbounded slot. It is shown that in this problem the qualitative features of the interface evolution do not differ from the previously considered case of the Hele-Shaw flow in a channel-type cell. 相似文献
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In this paper,the formation of the coherent structures in the wall region of aturbulent boundary layer was studied,using the nonlinear theory of the hydrodynamicstability.The spanwise and streamwise wavelengths of the most amplified unstablewave obtained by this study were found in good agreement with the experiments,whichmakes the distinct feature of this study in the present paper,as the basis of thestability analysis,a more rational velocity profile has been used,which is different fromthat of the turbulent mean flow.And also,the new nonlinear theory was used.Theresult is useful in understanding of the quasi-periodicity of the coherent structure in theturbulent boundary layer. 相似文献
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Numerical solutions are presented for two-dimensional low Reynolds number flow in a rotating tank with stationary barriers. The boundary element method is employed, assuming straight panels and quadratic source distribution. The feasibility of repositioning the nodes as a way to minimize the error is explored. A stretching parameter places smaller elements near the re-entrant regions. Elementary error analysis shows uniform improvement in the solution with stretching. The changing eddy pattern for different numbers and sizes of the barriers is compared with experimental results. 相似文献
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The paper addresses a problem of plane elasticity for a doubly connected body with outer and inner boundaries in the form
of regular polygons with a common center and parallel sides. The neighborhoods of the vertices of the inner boundary are unknown
equal full-strength smooth arcs symmetric about the rays coming from the vertices to the center. It is assumed that this elastic
body is inserted into a hole of a rigid body, with the hole boundary coinciding with the outer boundary of the elastic body.
Absolutely smooth rigid punches with rectilinear bases are pressed into all the rectilinear sections of the inner polygonal
boundary of the elastic body. There is no friction between the elastic and rigid bodies. The unknown arcs are free from external
stresses. Complex variable theory is used to determine the unknown arcs and the stress state of the elastic body
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 3, pp. 110–118, March 2006. 相似文献
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The implementation of solid-fluid boundary condition has been a major challenge for dissipative particle dynamics(DPD) method. Current implementations of boundary conditions usually try to approach a uniform density distribution and a velocity profile close to analytical solution. The density oscillations and slip velocity are intentionally eliminated, and different wall properties disappear in the same analytical solution. This paper develops a new wall model that combines image and frozen part... 相似文献
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In this paper, the differences of turbulent coherent structure between the smooth and rough boundary layers are analysed. Based on the discussing the transient properties from the smooth wall to the rough wall, the physical model of coherent structure for the rough boundary layer are established. The width of slowly-moving turbulent spot and the bursting time are obtained, which are in agreement with experimental results.The project supported by the National Nature Science Foundation of China 相似文献
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Pieranita Castellani Rizzonelli 《Journal of Elasticity》1973,3(4):225-259
An existence and uniqueness theorem is proved for the first boundary value problem of classical elasticity, relating to a broad class of three-dimensional domains whose boundaries may have edges and vertexes.The qualitative properties, up to the boundary, of the solution are investigated.
Résumé On démontre un théorème d'existence et unicité pour le premier problème de valeurs au contour de l'élasticité classique, concernant une large classe de domaines de l'éspace à trois dimensions, avec des frontières présentant des arètes et des sommets.On étudie les propriétés qualitatives, jusque'au contour, de la solution.相似文献