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本文提出了一种计算环加肋圆柱壳稳定性的新方法-复合有限条法。该方法能够在一个复合有限条元中计入若干个横向加肋的影响,并能考虑肋骨的偏心,是一种子结构方法。算例表明,复合有限条法具有很高的求解精度和效率,是一种分析加肋柱壳结构的较理想方法。该方法不仅能够计算环加肋圆柱壳的总体失稳临界载荷,而且可计算其局部失稳临界载荷。 相似文献
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水下爆炸载荷作用下环肋加筋圆柱壳结构的弹塑性动力屈曲 总被引:2,自引:0,他引:2
为研究水下爆炸载荷作用下潜艇结构的动力屈曲现象,以潜艇耐压结构的简化模型环肋加筋圆柱壳结构为研究对象,建立流固耦合有限元分析模型,应用瞬态有限元分析程序MSC.Dytran对该结构在水下爆炸冲击载荷作用下的弹塑性动力屈曲行为进行研究,基于Budiansky-Roth准则和Southwell方法确定环肋加筋圆柱壳结构的临界屈曲载荷,讨论结构动力屈曲的影响因素如载荷强度、网格密度、径厚比、长径比、加筋截面间距、加筋尺寸等对环肋加筋圆柱壳结构动屈曲模态和临界屈曲载荷的影响。结果表明:采用建立的流固耦合有限元分析模型,应用动力瞬态有限元软件MSC.Dytran可以对加筋圆柱壳结构的动力屈曲行为进行模拟,模型网格尺寸大小、结构几何参数对结构的动力屈曲临界载荷都有一定的影响,其中加筋圆柱壳结构的径厚比对结构的动力屈曲临界载荷影响最为显著。 相似文献
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有环壳过渡段的锥—柱组合壳的应力和稳定性 总被引:1,自引:0,他引:1
用解析方法计算了受静水外压载荷作用的有环壳过渡段的锥—柱组合壳中的应力值,并用瑞利法计算了其失稳临界载荷。计算结果说明,利用环壳过渡值锥—柱壳形成光滑连接,可使连接部位的局部应力值显著降低,并使失稳临界载荷有所提高 相似文献
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受弯脱层层板的局部失稳临界载荷的有限元分析 总被引:1,自引:1,他引:1
含脱层的复合材料层板承受弯曲载荷作用会产生跳跃失稳,还常常引起脱层扩展,从而导致结构失效。本文用基于一阶剪切层板理论的几何非线性有限单元法分析了受弯曲曲载荷作用下含脱层板的人稳的临界载荷。本文指出分叉失稳产生了跳跃失稳,而该跳跃失稳与浅圆拱或薄圆柱壳受向心压力作用下的跳跌 同,在整体平衡路径上没有一个极限点。本文对临界载计算结果比使用能量准则的结果要小,文中给出了原因。 相似文献
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本文提出了一种分析环加肋开孔柱壳屈曲问题的混合有限条──有限元法。环加肋柱壳作为一个构造上的正交各向异性壳处理,柱壳非开孔区采用有限条元离散,开孔区采用有限单元离散。在有限条元与有限单元交界面上,根据位移协调条件建立条元和单元的耦合关系,并据此构造一种特殊的过渡单元、联接条元和单元,进行整体分析。算例表明,这一方法对开孔柱壳屈曲问题的分折十分有效。 相似文献
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通过将升阶谱与有限条方法相结合,得到了以多项式级数为形函数的升阶谱有限条方法,并采用该方法对复合材料壁板结构在复杂边界条件下,受轴压、侧压及剪切载荷复合作用下的临界稳定性问题进行分析。数值算例结果表明,该方法综合了升阶谱和有限条的优点,可以快速稳定的精确求解复合材料壁板结构的临界失稳载荷。 相似文献
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本文给出了以环肋加强的圆柱壳在液压作用下屈曲形态和临界载荷的计算方法.根据组合结构的方法,建立了一组肋和肋间壳段的稳定微分方程组.在肋的截面高度、偏心距、截面总面积ΣF_r、总抗弯刚度ΣE_rI_(G_ra)不变的前提下,而使环肋的数目趋于无穷大,从而得到了作为组合的环肋加强壳的初次近似的正交各向异性壳模型及其弹性关系.可以进一步寻求方程组的级数解,其首项代表零阶近似解,亦即上述等效正交各向异性壳的解,其余各项代表逐次渐近的修正解,或等效壳和真实的环肋加强组合壳解的误差.根据误差的估计可以给出简化为等效各向异性壳的判据.最后给出了算例并与其它作者的方法进行了比较.计算结果表明与实验符合得很好. 相似文献
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The efficient compound strip method is used to analyse the buckling of ring-stiffened cylindrical shells under hydrostatic pressure. The eccentricity of stiffeners is taken into account. Numerical examples are given to illustrate the efficiency and accuracy of this method. 相似文献
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M. Bagheri A. A. Jafari M. Sadeghifar 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(11):1639-1649
In this research, the general axial and radial buckling optimization of ring-stiffened cylindrical shells is implemented by
the genetic algorithm (GA). The stiffened shell is subjected to four constraints including the fundamental frequency, the
structural weight, the axial buckling load, and the radial buckling load. In addition, six design variables including shell
thickness, number of stiffeners, stiffeners width and height, stiffeners eccentricity distribution order, and stiffeners spacing
distribution order are considered. In analytical solution, the Ritz method is applied and stiffeners are treated as discrete
elements. The effect of the weighting coefficients of the objective functions on the optimum solution is studied. The results
show that optimized stiffening a cylindrical shell leads to a lower structural weight, higher natural frequencies, and larger
axial and radial buckling loads, simultaneously. In addition, the upper and lower bounds of the design variables influence
the optimum results considerably. It is also found that the distributions of eccentricity and spacing of the stiffeners influence
the magnitudes of the axial and radial buckling loads considerably. 相似文献
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《应用数学和力学(英文版)》2017,(5)
In this paper, Donnell's shell theory and smeared stiffeners technique are improved to analyze the postbuckling and buckling behaviors of circular cylindrical shells of stiffened thin functionally graded material(FGM) sandwich under an axial loading on elastic foundations, and the shells are considered in a thermal environment. The shells are stiffened by FGM rings and stringers. A general sigmoid law and a general power law are proposed. Thermal elements of the shells and reinforcement stiffeners are considered. Explicit expressions to find critical loads and postbuckling load-deflection curves are obtained by applying the Galerkin method and choosing the three-term approximate solution of deflection. Numerical results show various effects of temperature, elastic foundation, stiffeners, material and geometrical properties, and the ratio between face sheet thickness and total thickness on the nonlinear behavior of shells. 相似文献
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《应用数学和力学(英文版)》2017,(1)
The postbuckling of the eccentrically stiffened circular cylindrical shells made of functionally graded materials(FGMs),subjected to the axial compressive load and external uniform pressure and filled inside by the elastic foundations in the thermal environments,is investigated with an analytical method.The shells are reinforced by FGM stringers and rings.The thermal elements of the shells and stiffeners in the fundamental equations are considered.The equilibrium and nonlinear stability equations in terms of the displacement components for the stiffened shells are derived with the third-order shear deformation theory and Leckhniskii smeared stiffener technique.The closed-form expressions for determining the buckling load and postbuckling load-deflection curves are obtained with the Galerkin method.The effects of the stiffeners,the foundations,the material and dimensional parameters,and the pre-existent axial compressive and thermal load are considered. 相似文献
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M. Talebitooti M. Ghayour S. Ziaei-Rad R. Talebitooti 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(3):201-215
In this paper, an analytical solution for the free vibration of rotating composite conical shells with axial stiffeners (stringers)
and circumferential stiffener (rings), is presented using an energy-based approach. Ritz method is applied while stiffeners
are treated as discrete elements. The conical shells are stiffened with uniform interval and it is assumed that the stiffeners
have the same material and geometric properties. The study includes the effects of the coriolis and centrifugal accelerations,
and the initial hoop tension. The results obtained include the relationship between frequency parameter and circumferential
wave number as well as rotating speed at various angles. Influences of geometric properties on the frequency parameter are
also discussed. In order to validate the present analysis, it is compared with other published works for a non-stiffened conical
shell; other comparison is made in the special case where the angle of the stiffened conical shell goes to zero, i.e., stiffened
cylindrical shell. Good agreement is observed and a new range of results is presented for rotating stiffened conical shells
which can be used as a benchmark to approximate solutions. 相似文献
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邵文蛟 《应用数学和力学(英文版)》1984,5(6):1831-1851
An analysis of the postbuckling strength of stringer stiffened cylindrical shells, subject to axial compression is described. The method used in this paper is based on plastic analysis extending Murray’s method which was used to analyse postbuckling behaviour of stiffened plates loaded axially and in bending. The mechanism tripping of stringer and crumpling of shell plate is described based on how the test specimens are deformed after buckling.Finally the theoretical analyses are compared with the experimental results of steel specimens. The theoretical results coincide quite well with the experimental data. It should therefore be possible to use the method described here to analyse postbuckling strength of stringer stiffened cylindrical shells and to estimate energy absorption capabilities in relation to collision studies. 相似文献
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A theory is derived for calculation of the influence of elastic edge restraints on the vibrations and buckling of stiffened cylindrical shells. The stiffeners are considered “smeared” and the edge restraints can be axial, radial, circumferential or rotational. Extensive computations are performed for special kinds of stringer-stiffened shells, and the theoretical predictions are compared with experimental results. A method of definition of equivalent elastically restrained boundary conditions by use of vibration tests is discussed. Application of this technique to tests on 10 shells significantly reduces the scatter in the ratio of experimental to predicted buckling loads. 相似文献
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George E. Warren 《Experimental Mechanics》1975,15(5):201-208
This paper presents the three-dimensional photoelastic analyses accompanied by extensive finite-element studies of several thin-shell pressure vessels with various cylindrical intersections. The models consisted of right circular cylindrical shells with diameter-to-thickness ratios of 220, reinforced with circumferential, longitudinal and diagonal T-stiffeners. The cylindrical shells and stiffeners were intersected by various smaller cylinders producing complex intersection joints which included radial and angular fillets. Each of the models was constructed from 80 to 150 parts prepared from flat sheets, “contour-cast” shells, and milled machined parts. The model techniques as well as the machining, assembling and testing methods of the pressure vessels are presented. 相似文献
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Xinping Zhou 《Acta Mechanica Solida Sinica》2012,25(2):168-176
Based on the Flügge shell theory,equations of motion of ring-stiffened thin-walled cylindrical shells conveying fluid are developed with the aid of the Hamilton's principle.Analysis is carried out on t... 相似文献
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组合圆柱壳静态屈曲的几个影响因素分析 总被引:2,自引:1,他引:2
本文的研究是以“九五”国家科技攻关专题“快堆主钠池堆芯抗震性能的安全评价方法研究、中的屈曲研究子课题为背景展开的,所用模型简化自中国实验快堆钠池主容,是由薄壁圆柱壳和多个加劲肋结构而成的组合圆柱壳体,本文分别采用大型有限元程度ANSYS 5.4和LGOR FEAS(SUPER SAP 93),对该壳体进行了常温时水平,轴向荷载共同作用静态屈曲的计算,同时考虑了诸如塑性,边界条件及初始缺陷等因素的影响,并进行了相关实验研究,最后将有限元计算结果与实验所获得的静屈曲荷载进行比较,结果吻合较好。 相似文献