共查询到20条相似文献,搜索用时 62 毫秒
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将单位支座位移法推广应用于超静定结构的未知支座反力计算,建立并证明了相应的退化虚位移方程,推导指出超静定结构支座反力的影响线即为相应单位支座位移所引起的位移曲线。而且,展示了几个求解超静定梁支座反力的算例. 本文工作可供大学生和教师们在结构力学相关知识的学习和教学中借鉴参考. 相似文献
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矩形薄板分析的大位移几何非线性有限元线法 总被引:1,自引:0,他引:1
本文建立了分析矩形薄板的大位移几何非线性有限元法理论,导出了相应的大位移非线性计算公式,并解决了板组结构中板元相连处位移连续性和互约束协调性问题。算例结果比较表明,本文方法可靠、精度高。 相似文献
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提出了用Maple 编程绘制无铰拱影响线的解析法. 绘制了抛物线无铰拱在单位竖向移动载荷作用下,3 个多余未知力的影响线;指定截面上的弯矩,剪力和轴力的影响线;支座水平约束力,垂直约束力及约束力矩的影响线. 实例表明,利用Maple 强大的符号运算功能,使用解析法绘制无铰拱影响线,速度快,方法简单,能同时给出影响线的解析表达式. 相似文献
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动支座对拱结构抗爆承载力的影响 总被引:1,自引:0,他引:1
建立了具有动支座拱的计算模型,该模型考虑了竖向的弹性支承和阻尼支承、水平向弹性支承和扭转约束等柔性支承形式。基于大变形动力微分方程并利用有限差分方法,研究了动支座拱在爆炸荷载作用下的动力响应,并分析动支座对结构承载力的影响。研究表明:动支座对拱的抗爆承载能力有较大影响,不同形式的柔性支承对拱承载力的影响截然不同,竖向弹性支承能够使爆炸荷载作用下拱的弯矩峰值减小,并且使到达峰值的时间增加,提高了拱的抗爆或承受瞬态荷载的能力。而水平弹性支承使拱的内力值和相对位移值增大,对结构的承载力不利。 相似文献
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Chang and Slattery (1986, 1988b) introduced a simplified model of dispersion that contains only two empirical parameters. The traditional model of dispersion (Nikolaevskii, 1959; Bear, 1961; Scheidegger, 1961; de Josselin de Jong and Bossen, 1961; Peaceman, 1966; Bear, 1972) has three empirical parameters, two of which can be measured in one-dimensional experiments while the third, the transverse dispersivity, must be measured in experiments in which a two-dimensional concentration profile develops. It is found that nearly the same linear stability behavior results from using either model. 相似文献
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Based on the strain formulation of the quasi-conforming finite element, displacement functions are constructed which have
definite physical meaning, and a conclusion can be obtained that the coefficients of the constant and the linear strain are
uniquely determined, and the quasi-conforming finite element method is convergent to constant strain. There are different
methods for constructing the rigid displacement items, and different methods correspond to different order node errors, and
this is different from ordinary displacement method finite element.
Contributed by TANG Li-min
Biography: HE Dong-sheng (1964-) 相似文献
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IntroductionMostofthefiniteelementsareconstructedbyusingdisplacementfiniteelementmethod .Bysupposingthedisplacementfunctionsintheelement,andusingtheprincipleofminimumpotentialenergy,theelementstiffnessmatrixcanbeformulated .Ifthedisplacementfunctioninth… 相似文献
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Chang Dae Han 《Applied Scientific Research》1970,22(1):223-238
The effect of radial diffusion on the performance of a liquid-liquid displacement process is considered in fluid flow between
porous parallel plates and through a porous tube, as examples of a two-zone problem in unsteady-state mass transfer. The double
Laplace transformation is applied to the system equations. In obtaining the inversion of the Laplace transformed equations
the first inversion (with respect to the transformed dimensionless axial distance) is performed by use of the residue method,
and then the second inversion (with respect to the transformed dimensionless time) is performed by use of the numerical Laplace
transform technique advanced by Bellman et al. A numerical example is shown and discussed. 相似文献
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《International Journal of Solids and Structures》1999,36(8):1129-1147
This paper presents a further development of the Boundary Node Method (BNM) for 2-D linear elasticity. In this work, the Boundary Integral Equations (BIE) for linear elasticity have been coupled with Moving Least Square (MLS) interpolants; this procedure exploits the mesh-less attributes of the MLS and the dimensionality advantages of the BIE. As a result, the BNM requires only a nodal data structure on the bounding surface of a body. A cell structure is employed only on the boundary in order to carry out numerical integration. In addition, the MLS interpolants have been suitably truncated at corners in order to avoid some of the oscillations observed while solving potential problems by the BNM (Mukherjee and Mukherjee, 1997a) . Numerical results presented in this paper, including those for the solution of the Lamé and Kirsch problems, show good agreement with analytical solutions. 相似文献
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Summary Observations are reported on linear low-density polyethylene in isothermal torsional oscillation and relaxation tests at various temperatures ranging from room temperature to 110 C. Constitutive equations are derived for the viscoelastic response of a semicrystalline polymer at small strains. The polymer is treated as an equivalent network of strands bridged by junctions (entanglements, physical cross-links on the surfaces of crystallites and lamellar blocks). The network is thought of as an ensemble of meso-regions with various potential energies for rearrangement of strands. Two types of meso-domains are introduced: active, where strands separate from temporary junctions as they are excited by thermal fluctuations, and passive, where detachment of strands is prevented by the surrounding macromolecules. The time-dependent behavior of the ensemble reflects separation of active strands from their junctions and merging of dangling strands with the network. Stress–strain relations are developed by using the laws of thermodynamics. The governing equations involve six material constants that are found by fitting the experimental data. The study focuses on the effects of (i) temperature, (ii) the deformation mode (torsion versus bending), and (iii) the loading program (oscillations versus relaxation) on the adjustable parameters.This work was partially supported by the West Virginia Research Challenge Grant Program 相似文献
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Lewis Wheeler 《Journal of Elasticity》1971,1(2):121-124
In recent separate investigations, Kirchhoff's classical uniqueness theorem of elastodynamics has been extended in two ways. Gurtin and Toupin generalized the theorem to encompass bodies possessing an elasticity tensor that obeys the semi-strong ellipticity condition, whereas the author has extended the theorem to unbounded regions. These two results are brought together in the present paper.
Resume Dans deux études récentes, le champ d'application du théoréme classique de Kirchhoff sur l'unicité de l'élastodynamique a été élargi de deux manières différentes. Gurtin et Toupin l'ont généralisé pour inclure les corps possédant un tenseur d'élasticité obéissant à la condition d'ellipticité demi-forte, alors que le présent auteur l'a étendu aux régions non finies. Ces deux résultats ont été combinés dans la présente communication.相似文献
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P. L. Fuhr D. Huston J. G. Beliveau P. J. Kajenski W. B. Spillman 《Experimental Mechanics》1991,31(2):185-188
An optical technique has been developed whereby two angles and linear displacement can be simultaneously measured in a noncontact fashion. The method depends upon the properties of diffraction gratings with linear variation of period along their length and photodetection using CCD arrays. The grating is attached to a structure at a point of interest while all other system components are placed at a remote location. Experimental results obtained using this technique are presented and compared with theory. 相似文献
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In this paper the linear stability of immiscible displacement in porous media is examined by numerical methods. The method of matched initial value problems is used to solve the eigenvalue problem for displacement processes pertaining to initially mobile phases. Both non capillary and capillary displacement in rectilinear flow geometries is studied. The results obtained are in agreement with recent asymptotic studies. A sensitivity analysis with respect to process parameters is carried out. Similarities and differences with the stability of Hele-Shaw flows are delineated.This is a revised version of paper SPE 13163, presented at the 59th Annual Technical Conference of the Society of Petroleum Engineers, Houston, Texas, 16–19 Sept. 1984. 相似文献