共查询到17条相似文献，搜索用时 187 毫秒
1.
Zhou Chengti Wang Liedong 《大连大学学报》1993,(1)
本文用汉密尔顿原理导出了复合材料叠层圆柱壳的非线性动力稳定性的控制微分方程。在基本方程中包括了非线性大挠度、圆柱壳的初始几何缺陷,以及动力载荷的惯性力等因素的影响。本文的目的是分析复合材料圆柱壳的参数共振和确定壳体结构动力屈曲时的稳定性区域和不稳定性区域,作为求解的例题,本文对三种复合材料圆柱壳进行了数例计算:即 T300—5208石墨-环氧壳体,ARALL 叠层铝合金壳体,和 E-玻璃-环氧壳体,结果表明它们具有相当不同的动力稳定性能.由本文所得出的计算结果和分析结论对于考虑和设计复合材料圆柱壳的动力稳定性具有重要的实用意义. 相似文献
2.
复合材料叠层板非线性动力稳定性理论的几个基本问题 总被引：1，自引：0，他引：1
本文研究了复合材料叠层板在周期性动力谐载荷作用下的非线性动力稳定性理论中的几个基本问题。其内容包括：用Hamilton原理建立一般性基本方程,考虑了大挠度非线性;惯性力的影响;耦合效应影响,横向剪切效应的影响,以及几何初始缺陷困数等。 相似文献
3.
研究了复合材料叠层板的初始缺陷和拉伸-弯曲耦合对于其振动、屈曲和非线性动力稳定性的影响,推导了控制方程,这是一个修正的非线性Mathieu方程,进行了5种典型复合材料的数值计算,它们是玻璃环氧Scotch-1002,芳纶环氧Kevlar-49,硼环氧B4/5505,石墨环氧T300/5208和AS/3501,结果表明,由于初始缺陷以及耦合效应的存在,使叠层板对于进入参数共振更加敏感,并且其振幅大于无初始缺陷或者无耦合效应的叠层板,对于不同材料的复合叠层板,尤其是层数较少的板,耦合效应是不相同的,在板结构的屈曲和动力稳定性设计中,如果忽略了耦合效应的影响,其不安全性将超过10％以上。 相似文献
4.
Zhou Chengti 《大连大学学报》1992,(1)
本文运用柯依脱理论(Koiter'sTheory)对于复合材料圆柱壳屈曲性能的初始缺陷影响进行了一般性分析,为复合材料壳体的初始缺陷敏感度分析建立了基本控制方程;壳体的初始缺陷被设定为具有某些固定形式的或者是随机形式的,为了讨论和比较各种复合材料叠层壳体的缺陷敏感度的影响,用数值算例计算了由玻璃/环氧,硼/环氧,和炭/环氧等复合材料所组成的圆柱壳体的届曲性能。 相似文献
5.
Wang Liedong 《大连大学学报》1993,(4)
形如 f″(x)+g(x)·f(x)=0的微分方程,其中 g(x)是 x 的周期函数.这类方程就是马奇耶方程.马奇耶(Mathieu)方程在实际工程中有着广泛的应用.关于它的周期解的研究,是结构动力屈曲分析的理论基础;同时也是常微分方程稳定性理论的—个重要内容.在马奇耶方程的周期解中,稳定与不稳定解的分界线即临界解是十分重要的.本文给出了临界解的求解方法,证明了临界频率方程的收敛性,讨论了某些干扰因素对临界解的影响。在实际工程中,这些干扰因素体现在结构阻尼,结构初始缺陷,结构的非线性几何点系结构的纵向惯性矩及转动惯性矩、复合材料的耦合效应等.计算结果表明,对于马奇耶方程的微小干扰,都将严重影响其临界解甚至改变解的性质.因此,在分析结构动力屈曲问题时,必须考虑问题所能包含的上述各项因素. 相似文献
6.
《东南大学学报》2016,(1)
为了研究初始几何缺陷和材料非线性对弦支穹顶稳定性分析的影响,以江苏文化城体育馆类椭圆形弦支穹顶为算例,进行了模态分析.然后,对弦支穹顶与单层网壳进行了稳定性能对比研究,包括线性屈曲、几何非线性屈曲、考虑初始几何缺陷的几何非线性屈曲以及同时考虑几何-材料非线性的双非线性屈曲.结果表明,索杆系增加了弦支穹顶的整体性,降低了单层网壳对初始几何缺陷的敏感性,但对结构刚度、自振频率、线性屈曲荷载、无初始缺陷的非线性屈曲荷载等影响不大.当考虑初始几何缺陷和材料非线性时,2种结构的极限稳定承载能力均大幅下降,表明低矢跨比弦支穹顶对初始几何缺陷和材料非线性较为敏感.此外,活载分布模式对结构失稳模态影响较大,满跨活载并不一定是最不利的活载分布模式. 相似文献
7.
从工程实例出发,对一座钢管混凝土拱桥建立了有限元模型,从线弹性和几何非线性两个方面进行了数值分析,分析表明该桥的屈曲稳定比较可靠,结构失稳模态均为拱肋面外失稳,表明拱肋的横向刚度相对系梁较弱. 相似文献
8.
《浙江大学学报(A卷英文版)》2017,(4)
目的:大型钢筒仓结构在正常装卸料过程中极易发生各种失稳破坏。本文旨在分析多种长细比的大型钢筒仓结构在散料荷载作用下的屈曲性能,为结构的稳定设计提供理论依据及技术支持。创新点:1.提出散料荷载作用下大型钢筒仓结构屈曲分析的4种典型工况:轴对称卸料荷载工况、小偏心卸料荷载工况、大偏心卸料荷载工况和大偏心装料荷载工况;2.建立了适用于不同屈曲分析类型的多种数值模型,研究了结构的稳定性能,并分析了各种非线性、初始几何缺陷、仓壁厚度的分布和基底嵌固刚度等对结构稳定性能的影响。方法:1.根据不同工况下散料荷载分布的特点和屈曲分析类型的差异,通过非线性有限元方法,研究结构在四种散料荷载工况下的稳定性能;2.通过研究结构在各种非线性屈曲分析下的荷载-位移全过程响应,确定结构的屈曲临界荷载和结构的稳定承载力;3.比较各种荷载工况下结构的屈曲临界荷载、屈曲模态及仓壁厚度分布特点,分析结构用钢量指标的变化。结论:1.非线性屈曲分析的荷载-位移曲线是高度非线性的,不同长细比钢筒仓的屈曲平衡路径之间有较大差异。2.钢筒仓结构的屈曲延性随长细比的减小而显著增大。3.材料非线性对结构的稳定性极为不利;几何非线性和初始几何缺陷对结构稳定性能的影响与结构的长细比密切相关。4.壁厚的分布对钢筒仓的稳定承载力和屈曲模态影响很大;设计时应考虑仓壁壁厚的不同组合形式,并确定使结构取得最大稳定承载力的仓壁最优分布形式。5.装料或卸料过程中的偏心使结构的储存效率(容耗比指标)显著降低。 相似文献
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10.
杨兰玉 《常熟理工学院学报》2011,25(4):75-78
ANSYS是通用的、大型的有限元分析CAE软件,使用ANSYS软件可以求解静态和瞬态非线性问题.本文在分析了圆柱薄壳结构的特点、分类和应用的基础上,对圆柱壳体的稳定性进行了研究,建立了圆柱壳体非线性力学方程.在ANSYS平台下,对典型的圆柱壳体进行了仿真,为进一步深入研究圆柱壳体非线性问题提供了借鉴. 相似文献
11.
The effect of axial shallow groove on the nonlinear dynamic response and buckling of laminated cylindrical shells subjected to radial compression loading was investigated. Based on the first-order shear deformation theory （FSDT）, the nonlinear dynamic equations involving the transverse shear deformation and initial geometric imperfections were derived with the Hamilton philosophy. The axial shallow groove of the laminated composite cylindrical shell was treated as the initial geometric imperfections in the dynamic equations. A semi-analytical method of expanding displacements and loads along the circumferential direction and employing the finite difference method along the axial direction and in the time domain is used to solve the governing equations and obtain the dynamic response of the laminated shell. The B-R criterion was employed to determine the critical loads of dynamic buckling of the shell. The effects of the parameters of the shallow groove on the dynamic response and buckling were discussed in this paper and the results show that the axial shallow grooves greatly affect the dynamic response and buckling. 相似文献
12.
考虑剪切效应有限变形粘弹性板的动力稳定性 总被引：4，自引：0，他引：4
Based on Reddy‘s theory of plates with higher-order shear deformations and the Boltzmann superposition principles,the governing equations were established for dynamic stability of viscoelastic plates with finite deformations taking account of shear effects,The Galerkin method was applied to simplify the set of equations.The numerical methods in nonlinear dynamics were used to solve the simplified system.It could e seen that there are plenty of dynamic properties for this kind of viscoelastic plates under transverse harmonic loads.The influences of the transverse shear deformations and material parameter on the dynamic behavior of nonlinear viscoelatic plates were investigated. 相似文献
13.
动态松驰法(DR法)是求解工程实际非线性问题的一种有效的、简单的方法、本文采用DR法首次对计及湿度影响的复合材料叠层扁壳的非线性弯曲问题进行了分析。 相似文献
14.
lintroductionTileHamilton'systemwasfirstestablishedinthegeometricaloptics,andwasappliedtothetheoreticalmechanicslater.ItsbasicideaistotransformtheEuclidspacetothesymplecticgeometryspaceforcomputing,thatistosay,theLagrangeequationsarechangedintotheHamilton… 相似文献
15.
Zhiming Ye Ph. D. 《上海大学学报(英文版)》1997,1(1):28-35
In this paper, a new nonlinear formulation of plates, including shear and rotatory inertia and transverse normal stress effects,
is developed by means of general assumptions, of which the von Karman-type formulation and some thick plate theories are special cases. To keep the formulation fairly general, the problem addressed
in this paper simultaneously includes: the effects of shear deformation according to the geometric deformation similarity
of the cross-section, the rotatory inertia, and the transverse normal stress. The three-dimensional compatible equations are
applied to derive the basic equations. Numerical results are given for linear and non-linear analysis of plates.
This Work was supported by the Natural Science Fundation of Shanghai for Returning Scholars 相似文献
16.
The effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells is investigated through experimental
and numerical buckling analysis using six welded steel cylindrical shell specimens. The relationship between the amplitude
of weld reinforcement and the axial plastic buckling critical load is explored. The effect of the material yield strength
and the number of circumferential welds on the axial plastic buckling is studied. Results show that circumferential weld reinforcement
represents a severe imperfect form of axially compressed welded steel cylindrical shells and the axial plastic buckling critical
load decreases with the increment of the mean amplitude of circumferential weld reinforcement. The material yield strength
and the number of circumferential welds are found to have no significant effect on buckling waveforms; however, the axial
plastic buckling critical load can be decreased to some extent with the increase of the number of circumferential welds. 相似文献
17.
Knitted fabric is very different from woven fabric due to its more complicated knitting structures. The buckling of knitted fabric sheets subjected to simple shear in the wale direction is investigated analytically in consideration of the large deformation of fabric sheet in critical configuration. The theory on instability of finite deformation is applied to the analysis. All the stress boundary conditions of knitted fabric sheet are satisfied. An equation to determine the buckling direction angle is derived. It is shown that there are two possible buckling modes, flexural mode and barreling mode. The buckling condition equations for the flexural mode and barreling mode are also obtained respectively. Numerical illustrations reveal that only the flexural mode can actually occur and the barreling mode cannot, which agrees with the experimental observations. For a permitted buckling mode on margin boundaries, the critical value of shear amount and the buckling direction angle can be determined. 相似文献