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21.
IntroductionU_shapedbellowsareusuallyseeninthepipelinesystem (Fig .1) ,whichareusedtocompensatefortheaxialmovement,therotationandthedeflectionofthepipelinesduetothethermalaction ,thebaseunequalsettlementsandtheinstallationerrors.Theaxisymmetricaldeformatio… 相似文献
22.
胡俍 《应用数学和力学(英文版)》1993,(6)
On the basis of paper[1],assuming the logarithm of thickness at arbitrary point on a U-shaped bellows meridian is linear with the logarithm of distance between that point and axis of symmetry,perturbation solutions of the corresponding problems of large axisymmetrical deflection are given.The effects of thickness distribution variation,which result from technology factors,on stiffness of bellows are discussed. 相似文献
23.
波纹管是一类子午线呈波纹状的旋转壳,作为弹性敏感元件和柔性连接件在航空仪表和管道工程中起着重要的作用。长期以来基于壳体理论的分析多限于轴对称变形问题。最近,虽然出现了以柔性旋转壳理论为基础的解决波纹管整体弯曲问题的解析解和数值解,但仍有必要通过别的途径加以验证和补充。为些,本文提出了波纹管在子午面内整体弯曲的半解析有限元解。把波纹管近似成有限个截顶锥壳的组合体,每个截顶锥为一个单元。将位移分量沿纬线用Fourier级数展开,沿子午线用多项式插值,截锥单元因此化为2节点的直线单元,每节点为4个自由度。显然,对于同等的RAM和CPU,线单元可比其他单元划得更小。于是,利用小单元条件,将一个单元内的壁厚和平行圆半径近似地当作不变量,给出了用显式表示的单元刚度矩阵,为直观分析结构参数对波纹管力学性能的影响提供了方便。在此基础上,计算了Ω型,C型和U型波纹管在纯弯矩作用下的变形和应力分布,所得结果和已有的解析解,数值解相符。本法不限于波纹管的计算分析。 相似文献
24.
U型波纹管及相关结构环向屈曲的有限元分析(Ⅰ)--基本方程及环板的屈曲 总被引:1,自引:2,他引:1
U型波纹管是现代管道系统中最常见的一种位移补偿器 ,它由环板和具有正、负Gauss曲率的半圆环壳组成 ,在管道所传输的介质的压力作用下会发生屈曲。其中环向屈曲最为复杂 ,精确的理论分析非常困难 ,有限元分析也不多见。作者在分析前人工作的基础上 ,以圆环壳段为单元 (特定的旋转壳段单元 ,能自动退化成环板单元 ) ,限于弹性范围和线性化特征值问题 ,对介质压力作用下U型波纹管及其相关结构 (圆环板、圆环壳、半圆环壳 )的环向屈曲问题进行了分析。考虑了结构屈曲前的弯曲 ,计及压力的二次势能 ,导出的应力刚度矩阵和载荷刚度矩阵是非对称的。全部工作分为三部分 :(Ⅰ )基本方程 ,环板的屈曲 ;(Ⅱ )圆环壳、半圆环壳的屈曲 ;(Ⅲ )波纹管平面失稳的机理。本文为第一部分 ,除推导公式外 ,对不同边界和不同内外径之比的环板在径向均匀压力作用下的环向屈曲进行了计算 (轴对称的径向屈曲作为特例得到 ) ,给出了前屈曲应力分布、临界载荷及相应的屈曲模态 ,并将临界压力的值与前人基于vonK偄rm偄n大挠度板的精确解进行了比较 ,吻合良好。 相似文献
25.
章冠人 《应用数学和力学(英文版)》1984,5(4):1521-1528
In this paper, the author proves that, for a nonlinear heat conduction equation, there is no discontinuous solution. Some methods of solution for a nonlinear conduction equation are depicted. For a plane interface, the reflection and transmission of a heat wave are given by the method of images. The 1st order of approximation of this method is proved. Lastly, the prevention of superheated electrons is laser implosion of deuterium tritium gas sphere with a shell made of high Z material is interpreted. 相似文献
26.
Summary The nonlinear integral equations for a U-shaped bellows with compressed angle and varying wall-thickness are derived according
to the simplified Reissner theory of large deflection for revolution shells and integral-equation method. The iteration procedure
for nonlinear analysis is developed by means of the integral equation iteration in conjunction with the gradient method. Numerical
solutions for a U-shaped bellows under the action of axial compression force and internal pressure are obtained, which are
compared with previous theories and experiments. The present results are shown to have a good accuracy, and may be applied
directly to the design of bellows.
Received 13 November 1997; accepted for publication 6 July 1999 相似文献
27.
(Ⅱ)是(Ⅰ)的具体应用。计算了Ω型波纹管的角向刚度、横向刚度和应力分布,并将所得结果与有关的细环壳理论及实验进行了比较。结果表明,单独用(Ⅰ)的非齐次解能够计算Ω型波纹管的纯弯曲,而且比细环壳理论更接近实际;但在横向位移作用下,(Ⅰ)的非齐次解只能部分地满足边界条件,此时应同时考虑齐次解的作用,即完整的一般解(Ⅰ)才能满足所有的要求. 相似文献
28.
Complex equations of flexible circular ring shells overall-bending in a meridian plane and general solution for the slender ring shells 总被引:1,自引:0,他引:1
IntroductionEquationsforcircularringshellsaredifficulttosolve.Theresearchofthisproblemstartedatthebeginningofthiscentury.Inthelate1970sandearly1980s,W.Z.Chien(1979,1980,1981)[1~3]rebuiltthecomplexequationsofaxis_symmetricallyloadedringshellspresented… 相似文献
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30.
The finite-element-displacement-perturbation method (FEDPM)for the geometric nonlinear behaviors of shells of revolution subjected to pure bending moments or lateral forces in one of their meridional planes (Ⅰ) was employed to calculate the stress distributions and the stiffness of the bellows. Firstly, by applying the first-order perturbation solution (the linear solution)of the FEDPM to the bellows, the obtained results were compared with those of the general solution and the initial parameter integration solution proposed by the present authors earlier, as well as of the experiments and the FEA by others.It is shown that the FEDPM is with good precision and reliability, and as it was pointed out in (Ⅰ) the abrupt changes of the meridian curvature of bellows would not affect the use of the usual straight element. Then the nonlinear behaviors of the bellows were discussed. As expected, the nonlinear effects mainly come from the bellows ring plate,and the wider the ring plate is, the stronger the nonlinear effects are. Contrarily, the vanishing of the ring plate, like the C-shaped bellows, the nonlinear effects almost vanish. In addition, when the pure bending moments act on the bellows, each convolution has the same stress distributions calculated by the linear solution and other linear theories, but by the present nonlinear solution they vary with respect to the convolutions of the bellows. Yet for most bellows, the linear solutions are valid in practice. 相似文献