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971.
经典弹性板理论采用了着名的克希霍夫(Kirchhoff)[1]-拉甫(Love)[2]的经典基本假定,在卡氏张量坐标xi(ι=0,1,2)中,这些基本假定是:(1)略去横向即x0轴向正应变,即假定e(00)=0;(2)略去横向剪应变,即假定e0α=0,其中α=1,2;(3)略去横向正应力,即假定σ00=0.人们利用这些假定,建立了应变位移关系和应力位移关系,再利用应力平衡的三维方程,通过跨厚度的积分,找到弹性板中面上的各待定量所应满足的经典理论方程。前文[3,4,5],曾在不用克希霍夫-拉甫经典假定的弹性板三维理论中建立了一种近似理论,但并未证明这种近似理论的唯一性,也没有研究相应的近似边界条件。本文将用三维弹性体的广义变分原理[6]研究相同的问题。本文通过变分驻值条件,求得唯一的近似方程和相应的近似边界条件。本文详细研究了一级近似的平衡方程和近似边界条件。 相似文献
972.
钱伟长 《应用数学和力学(英文版)》1984,5(3):1281-1296
In this paper, the variational principles of hydrodynamic problems for the incompressible and compressible viscous fluids are established. These principles are principles of maximum power losses. Their generalized variational principles are also discussed on the basis of Lagrangian multiplier methods. 相似文献
973.
This paper presents the solution of symmetrical deformation of circular membrane under the action of uniformly distributed loads in its central portion. Its limiting case is the solution of circular membrane under concentrated load at the center. This solution is the third solution of the circular membrane problems after the well-known Hencky’s solution. 相似文献
974.
The Calculation of Semi-circular Corrugated Tube——An Application of the General Solution of Ring Shell 总被引:1,自引:1,他引:0
In this paper, the deformation and stress distribution in semi-circular corrugated tube under axial force are calculated by
means of the general solutions of circular ring shell given in previous paper[1]. 相似文献
975.
钱伟长 《应用数学和力学(英文版)》1980,1(2):159-164
In this paper, the explicit forms of field functions in tetrehedron elements with 16 and 20 degrees of freedom are given in terms of volume coordinatesL
1,L
2,L
3,L
4 of tetrahedron. 相似文献
976.
The perturbation method is one of the effective methods for so-lving problems in nonlinear continuum mechanics.It has been de-veloped on the basis of the linear analytical solutions for the o-riginal problems.If a simple analytical solution cannot be ob-tained.we would encounter difficulties in applying this method tosolving certain complicated nonlinear problems.The finite ele-ment method appears to be in its turn a very useful means for sol-ving nonlinear problems,but generally it takes too much time incomputation.In the present paper a mixed approach,namely,theperturbation finite element method,is introduced,which incorpo-rates the advantages of the two above-mentioned methods and enablesus to solve more complicated nonlinear problems with great savingin computing time.Problems in the elastoplastic region have been discussed anda numerical solution for a plate with a central hole under tensionis given in this paper. 相似文献
977.
Smoke Control of Fires in Subway Stations 总被引:5,自引:0,他引:5
Falin Chen Shin-Chang Guo He-Yuan Chuay Shen-Wen Chien 《Theoretical and Computational Fluid Dynamics》2003,16(5):349-368
We investigate the effectiveness of the smoke control scheme of the Gong-Guan subway station (GGSS), a typical subway station
of the Taipei Rapid Transit System and whose mechanical control systems are also standard in modern subway station design.
Three-dimensional smoke flow fields under various kinds of fires are computed by computational fluid dynamics techniques
and the results are illustrated on various cross-sectional planes. Results indicate that the stack effect plays a deterministic
role in smoke control when a fire occurs near the stairwell; under such circumstances, no mechanical smoke control is necessary.
When a fire occurs in other places, such as at the end or the center of the platform, the current mechanical control schemes
of GGSS are effective; namely, the smoke can be well controlled, either it is confined to a small region or is evacuated from
the station, leaving the four exits free of smoke so that the passengers can escape through them. The effect of the platform
edge door (PED) on smoke control is also investigated. With the PED, the effectiveness of the present smoke control system
for fires occurring on the chassis of a train, a serious fire in the subway station, increases. We also propose an innovative
smoke control scheme with a PED, which turns out to be much more efficient in evacuating smoke than that currently used.
This study provides both valuable information for the design of passenger evacuation routes in fires as well as criteria
for the design of a smoke control system for subway stations.
Received 12 August 2002 and accepted 22 October 2002 Published online 14 February 2003
RID="*"
ID="*" The financial supports for this research from both the SinoTech Engineering Consultant Inc. and the National Science
Council under Grant NSC 89-2212-E-002-61 are gratefully appreciated.
Communicated by H.J.S. Fernando 相似文献
978.
979.
超临界流体萃取技术在核废料处理方面的应用 总被引:6,自引:0,他引:6
超临界流体;二氧化碳;综述;超临界流体萃取技术在核废料处理方面的应用 相似文献
980.