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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
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液压膨胀环动态拉伸碎裂的有限元模拟 总被引:1,自引:0,他引:1
液压冲击膨胀环实验平台能有效地实现韧性金属圆环在高应变率拉伸载荷作用下的动态断(碎)裂。本文采用流固耦合的有限元数值计算方法,模拟了实验过程中金属圆环在高压液体作用下的运动、变形和断裂现象。分析了装置和试件的接触应力对试件碎裂过程的影响并讨论了如何实现液压对试件的有效加载。计算结果表明,实验中的初始接触应力和液体的较长时间加载对试件的碎裂过程没有显著影响;在合理的加载条件下,液压膨胀环实验技术是研究固体动态拉伸碎裂的有效手段。 相似文献
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压力容器封头顶点开孔接管处,为了减小应力集中,常做成半径很小的圆角,如图1所示.因此应将接管处看成是包含有经向曲率半径R_1很小的圆环壳.当采用薄壳结构力学方法求得圆环壳的内力和内矩后,如仍采用薄壳的应力公式来计算最大应力,则误差将随着R_1的减小而更加增大.本文参照大曲率杆的应力计算方法建立了大曲率圆环壳对称变形的应力公式,可以较精确地计算出圆角处的局部应力.如图2所示,圆环壳子午面微段中面以及距离中面为z 沿经线的长分别为 相似文献
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船用加筋板架爆炸载荷下动态响应数值分析 总被引:15,自引:0,他引:15
针对船用加筋板架复杂结构在爆炸冲击波作用下的动态响应 ,采用商用高动态非线性有限元程序MSC/Dytran ,讨论了大尺寸加强结构板架迎爆承载问题 ,提出了复杂板架结构爆炸冲击波作用下动态响应的有限元计算方法 ,并进行了模型试验。试验结果与计算结果吻合较好 ,验证了应用程序及计算模型参数的稳定性和可靠性。对加筋板架两种承载形式 (大尺寸加强构件迎爆或背爆设置 )在爆炸冲击波作用下的动态响应 (板架中心挠度和塑性分布 )差异的分析研究表明 ,大尺寸骨架 (纵骨和肋骨 )背向爆炸冲击波设置将分散爆炸冲击波的冲击作用、减小板架变形、增强其抵抗爆炸冲击波冲击的能力 ,使结构偏于安全。 相似文献
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阶梯形变截面圆拱和圆环稳定计算的有效方法 总被引:4,自引:0,他引:4
利用等截面圆弧曲杆的稳定微分方程和本文导出的弯矩一般表达式,建立了静水压力作用下阶梯变截面圆拱和圆环稳定分析的代数方程组,得到了解析计算临界载荷的特征方程.算例表明本文方法简单有效 相似文献
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锅炉炉墙板梁结构随机响应的边界元方法 总被引:1,自引:0,他引:1
锅炉炉墙可简化成板,梁的组合结构,在燃烧脉动的激励下会形成随机性的振动。本文提出了一种借助于边界元方法进行随机激励作用下正交各向异性板,梁组合结构动力响应计算的一般方法。文中首先导出各向异性板,梁结构动力问题的边界积分方程,进而得到用于随机响应计算的板,梁结构的频率响应函数矩阵。在此基础上可以求出板,梁结构上任意点响应的均方值。这一方法的有效性在文中电站锅炉实际算例中得到了验证。 相似文献
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In this paper, we study the deformation and stability of a circular plate under its own weight and supported by a flexible concentric ring. Both bilateral and unilateral supports are considered. Von Karman’s plate model is adopted to formulate the equations of motion. A nonlinear Galerkin’s method based on two sets of assumed functions is used to discretize and solve the governing equations. Vibration method is used to predict the stability of the deformations. The linear analysis conducted previously predicts that the deformation is always axisymmetric. The current nonlinear analysis, however, shows that the axisymmetric deformation may become unstable when the dimensionless load, i.e., a ratio between the weight per unit area and the flexural rigidity of the plate, reaches a critical value. At this critical load, a stable non-axisymmetric deformation of the form cos nθ emerges following a pitch-fork bifurcation, where the integer n depends on the stiffness and the radius of the ring support. When the load increases further, more than one stable non-axisymmetric deformation may coexist. In a stable non-axisymmetric deformation with bilateral support, tension on the ring support may develop when the load reaches another critical value. In this situation, the circular plate will separate from the supporting ring in part of the angular region if the bilateral support is replaced by a unilateral one. The deformation with unilateral support is in general larger than the one with bilateral support. 相似文献
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Xuxi Qin Hanbing Liu 《Acta Mechanica Solida Sinica》2010,23(1):57-65
A new method for the determination of effective flange width under uniform load on simply supported box girder bridges considering shear lag effect is proposed in this paper. Based on the Symplectic Elasticity method, the flange slab of the box girder is simplified into a plane stress plate. Using equilibrium conditions of the plates, the Hamilton dual equations for top plate element is established. The analytical formulas of each plate element considering shear lag effect are derived. The closed polynomial effective width expression of flange slab under uniform load on the whole span length has been obtained. Through examples using the finite element method, the results obtained by the proposed method are examined and the accuracy of the proposed method is verified. 相似文献
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用加权余量法分析固支圆板和环板在Mises屈服条件下的极限荷载 总被引:3,自引:0,他引:3
应用加权余量法求出了承受线性荷载的固支圆板和承受均布荷载的内边界支承环板在 Mises屈服条件下的极限荷载的近似值 ,并与最大弯矩极限条件结果进行了比较 ,说明本文计算结果较合理。 相似文献
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本文导出了由位移表示的带初始挠度的粘弹性大挠度矩形薄板的运动方程。在简支边界条件下,应用分歧理论和Melnikov方法,研究在周期外力作用下系统的动力行为。给出了出现次谐分枝和马蹄态的条件。 相似文献
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L. I. Shkutin 《Journal of Applied Mechanics and Technical Physics》2006,47(2):282-288
The problem of a rod and a plate subjected to plane strain in the interval of the direct phase transformation is formulated
as a nonlinear boundary-value thermoelastic problem with an implicit dependence on temperature (through a phase parameter
simulating the volume fraction of new-phase crystals). An analytical solution of the problem of a rod bent into a ring and
a plate bent into a tube as a result of phase strains under the action of a small end bending moment is given. A numerical
analysis of the buckling problem of a titanium nickelide (alloy) rod (plate) under longitudinal compression in the interval
of the direct phase transformation shows that buckling becomes possible if the compressive load is much lower than the Euler
critical load calculated before the transformation. Branches of buckled equilibrium states corresponding to loads lower than
the Euler load are plotted as functions of the phase parameter. In all cases considered, the deflections increase abruptly
in the neighborhood of the critical points. The evolution of buckling modes is studied, and the phase-strain distributions
along the rod (plate) are shown.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 2, pp. 156–164, March–April, 2006. 相似文献
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研究静载荷作用下夹层圆板的超谐波共振问题.基于Hoff型夹层板理论,给出了静载荷作用下夹层圆板的非线性动力学方程.应用Galerkin法推导了静载荷作用下夹层圆板的轴对称非线性振动方程.运用多尺度法分别对系统的三次超谐波问题和二次超谐波问题进行了求解,并依据Lyapunov稳定性理论得到了系统稳态运动的稳定性判据.通过算例,得到了周边简支约束下夹层圆板三次超谐波共振和二次超谐波共振的幅频响应曲线图、振幅-静载荷响应曲线图、振幅-激励力幅值响应曲线图;研究了不同参数对系统振幅的影响规律,并对解的稳定性进行了分析. 相似文献
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The mill roller bearing is made up of an internal ring, middle rolls and an external ring, the analysis of which is a multi-bodies
contact problem. In this paper, based on the three-dimensional elastic contact BEM without friction, and using the structural
characteristics of roller bearings, middle rolls are described by elastic plate units of different shapes, which is placed
on the internal ring. The discontinuous traction problem of the contact element can be dealt with by the traction sub-element
method. Therefore the contact problem can be changed from one of multi-bodies to one of two-bodies. As an elastic deformation
of the plate element, it can be calculated by an elastic contact formula and is regarded as an equivalent gap to be put into
the total matrix equality. The face-to-face contact condition of displacement and traction on the element will serve as the
convergence judging condition. So convergence solution can be obtained before any geometry inconsistent on the contact element
may take place. Therefore, the three-dimensional distribution of load of the mill roller bearing can be achieved. It has been
proved that the calculating model of this method is visualized and simple, has fast convergence solution and higher accuracy,
making it an effective numerical method of designing and analyzing load characteristics of the mill roller bearing.
Project supported by the National Natural Science Foundation of China (50075075). 相似文献
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In this paper, the wave propagation and dynamic response of the rectangular FGM plates with completed clamped supports under impulse load are analyzed. The effective material properties of functionally graded materials (FGMs) for the plate are assumed to vary continuously through the plate thickness and be distributed according to a volume fraction power law along the plate thickness. Considering the effects of transverse shear deformation and rotary inertia, the governing equations of the wave propagation in the functionally graded plate are derived by using the Hamilton’s principle. A complete discussion of dispersion of the FGM plates is given. Using the dispersion relation and integral transforms, exact integral solutions for the FGM plates under impulse load are obtained. The influence of volume fraction distributions on wave propagation and dynamic response of the FGM plates is analyzed. 相似文献
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基于小波微分求积法的薄板弯曲分析 总被引:2,自引:1,他引:1
利用小波微分求积法(WDQM)对任意荷载作用下的薄板弯曲问题进行了求解分析。数值算例表明,小波微分求积法与一般的DQ法相比具有很好的适用性,特别是薄板受集中荷载或不连续分布荷载作用时,由于小波基函数的紧支撑特性与其对突变信号良好的描述能力,WDQ法的精度明显优于一般的DQ法,具有良好的应用前景。 相似文献