共查询到20条相似文献,搜索用时 15 毫秒
1.
本文给出了旋转壳与支承支柱系统组合结构线性稳定性分析的简化处理方案,即将空间梁系结构每根梁的单元刚度阵及几何阵按离散富氏系数变量叠加得等效刚度阵及几何阵。从所给算例知,这一简化处理是成功的,也说明稳定性分析反映的是结构的总体效应,局部区域的简化处理对整体结构临界载荷影响不大,但可使计算量大大减少。本文的计算方案及程序已应用于实际的冷却塔设计。 相似文献
2.
在Hamilton体系下,基于Euler梁理论研究了功能梯度材料梁受热冲击载荷作用时的动力屈曲问题;将非均匀功能梯度复合材料的物性参数假设为厚度坐标的幂函数形式,采用Laplace变换法和幂级数法解析求得热冲击下功能梯度梁内的动态温度场:首先将功能梯度梁的屈曲问题归结为辛空间中系统的零本征值问题,梁的屈曲载荷与屈曲模态分别对应于Hamilton体系下的辛本征值和本征解问题,由分叉条件求得屈曲模态和屈曲热轴力,根据屈曲热轴力求解临界屈曲升温载荷。给出了热冲击载荷作用下一类非均匀梯度材料梁屈曲特性的辛方法研究过程,讨论了材料的梯度特性、结构几何参数和热冲击载荷参数对临界温度的影响。 相似文献
3.
IntroductionDynamicbucklingisanimportantfailurephenomenonofthestructure ,whichisirradiatedbystronglaserbeam .Bucklingwillresultinthecatastrophicreductionofenduringloadingabilityofstructuresandcausesomeotherfailures.Intheso_called“reversepluggingeffect” … 相似文献
4.
5.
The partially embedded submarine pipelines might buckle laterally at some segments under high pressure and high temperature (HP/HT) conditions. The buckling pattern localization introduces an extra level of analytical complexity when compared with the periodic buckling pattern. In the presented paper the lateral buckling pipeline is modeled by an axial compressive beam supported by lateral distributing nonlinear springs taking the soil berm effects in the horizontal plane. It is found that the model is governed by a time-independent Swift–Hohenberg equation. Based on John Burke and Edgar Knobloch’s work we conclude preliminarily that the equation will have localized solutions. Besides the qualitative conclusion, by AUTO 07P the localized solutions of the equation are studied in detail. The snakes-and-ladders structure of localized solutions explains the transition of buckling modes in theory. The range of the possible critical axial forces is found out. Meanwhile two critical axial force formulas corresponding to the range ends are presented. Finally a typical submarine pipeline is analyzed as an illustration. 相似文献
6.
7.
《European Journal of Mechanics - A/Solids》2002,21(4):669-682
A methodology for the analysis of the mechanical behaviour of beams is presented, which relies on the lemma of stroboscopy, a tool from Non-Standard Analysis. This problem traces back to the conventional Euler's column load. Starting from a discrete rigid rod-torsional spring model of the beam, stroboscopy enables us to build a continuous model for the variation of the angular position along the beam. This position is characterised as a solution of a differential equation. A perturbation analysis of this equation, leads to buckling condition, in particular a sufficient buckling conditions for corrugated beams. 相似文献
8.
梁的轴向运动会诱发其产生横向振动并可能导致屈曲失稳,对结构的安全性和可靠性产生重大的影响。本文重点研究了横向载荷作用下轴向运动梁的屈曲失稳及横向非线性振动特性。基于Hamilton变分原理,建立了横向载荷作用下轴向运动梁的动力学方程,获得了梁的后屈曲构型。使用截断Galerkin法,将控制方程改写成Duffing方程的形式。用同伦分析方法确定载荷作用下轴向运动梁的非线性受迫振动的封闭形式的表达式。结果表明,后屈曲构型对轴向速度和初始轴向应力有明显的依赖性。通过同伦分析法得出非线性基频的显式表达式,获得了初始轴向力会影响非线性频率随初始振幅和轴向速度的线性关系。另外,轴向外激励的方向也会改变系统固有频率。 相似文献
9.
10.
11.
The dynamic buckling of an elastic-plastic column subjected to an axial impact by a rigid body was discussed by using the energy law. The traveling process of elastic-plastic waves under impact action was analyzed by characteristics method. The equation of lateral disturbance used to analyze the problem was developed by taking into account the effect of elastic-plastic stress wave. The power series solution of this problem has been the power series approach. The buckling criterion of this problem was proposed by analyzing the characteristics of the solution. The relationship among critical velocity and impact mass, critical buckling length, hardening modulus was given by using theoretical analysis and numerical computation. 相似文献
12.
13.
Twisting chirality is widely observed in artificial and natural materials and structures at different length scales. In this paper, we theoretically investigate the effect of twisting chiral morphology on the mechanical properties of elas- tic beams by using the Timoshenko beam model. Particular attention is paid to the transverse bending and axial buckling of a pre-twisted rectangular beam. The analytical solution is first derived for the deflection of a clamped-free beam under a uniformly or periodically distributed transverse force. The critical buckling condition of the beam subjected to its self- weight and an axial compressive force is further solved. The results show that the twisting morphology can significantly improve the resistance of beams to both transverse bending and axial buckling. This study helps understand some phenomena associated with twisting chirality in nature and provides inspirations for the design of novel devices and structures. 相似文献
14.
Yin Zhang 《International Journal of Non》2005,40(6):795-805
An axially compressed beam resting on a non-linear foundation undergoes a loss of stability (buckling) via a supercritical pitchfork bifurcation. In the post-buckled regime, it has been shown that under certain circumstances the system may experience a secondary bifurcation. This second bifurcation destablizes the primary buckling mode and the system “jumps” to a higher mode; for this reason, this phenomenon is often referred to as mode jumping. This work investigates two new aspects related to the problem of mode jumping. First, a three mode analysis is conducted. This analysis shows the usual primary and secondary buckling events. But it also shows stable solutions involving the third mode. However, for the cases studied here, there is no natural loading path that leads to this solution branch, i.e. only a contrived loading history would result in this solution. Second, the effect of an initial geometric imperfection is considered. This breaks the symmetry of the system and significantly complicates the bifurcation diagram. 相似文献
15.
‘Fluid buckling’ is a phenomenon characterized mainly by the existence of fluid toroidal oscillations during flow. It appears when a high viscosity fluid flows vertically against a flat surface and may occur in industrial applications, as in injection molding of a propergol in complex‐shaped cavities. These coiling or folding oscillations appear during the mold filling stage, leading to air entrapment. To understand and to model this free surface flow problem, a convected level set method is proposed. First, a sinus filter is applied to the distance function to get a smooth truncation far from the interface. Second, the reinitialization is embedded in the transport equation model, avoiding it as a separate step during calculation. In order to validate the method, numerical results are presented on classical interface capturing benchmarks. Finally, results are shown on two‐dimensional and three‐dimensional viscous jet buckling problems. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
16.
用有限个横向条带法构造了板桁组合结构板段考虑局部屈曲的空间位移模式。基于三维连续体的虚功增量方程,导出了横向条带板段单元的UL列式,并考虑了板段单元位形变化的影响。此计算方法自由度少,计算精度高,能用于大型板桁结构的几何非线性分析。文末计算了广东西江桥板桁组合结构模型梁,计算结果与实测结果吻合较好。 相似文献
17.
Introduction Inengineeringtechnology,thegradedmultiwebstructureofheterogeneousmaterials whichisappliedinaerofoilstructureandautomobilelightweightstructuresubstitutethe integralskinwebstructureforthetraditionalskinstiffenedstructure.Thismultiwebstructure i… 相似文献
18.
Based on a non-linear mathematical model of lateral buckling of a slender beam with a narrow rectangular cross section, the variational formulation of the two-parametric optimization problem is given in the dimensionless form. An optimal shape is obtained by solving the variational problem using the Rayleigh–Ritz method with the orthogonal system of trigonometric functions. By a partial solution of the Euler–Lagrange differential equation of the variational problem, a proof is given that in the case of the optimal shape, a maximal reference stress according to the total strain energy theory is constant along the beam. An example of extrapolation of the two-parametric optimization problem solution is represented. 相似文献
19.
爆炸冲击下复合材料层合扁球壳的动力屈曲 总被引:1,自引:0,他引:1
研究计及横向剪切的复合材料层合扁球壳在爆炸冲击载荷作用下的非线性轴对称动力屈曲问题。通过在复合材料层合扁球壳非线性稳定性的基本方程中增加横向转动惯量项并引入R.H.Cole理论的爆炸冲击力,得到爆炸冲击下复合材料层合扁球壳的动力控制方程,应用Galerkin方法得到用顶点挠度表达的爆炸冲击动力响应方程,并采用Runge-Kutta方法进行数值求解,采用Budiansky-Roth准则确定冲击屈曲的临界载荷,讨论了壳体几何尺寸对复合材料层合扁球壳冲击屈曲的影响;数值算例表明,此方法是可行的。 相似文献
20.
鄂国康 《应用数学和力学(英文版)》1997,18(10):975-986
I.IntroductionltwasuntiIl899thattheflrsttreatmentwaspub1ishedofflexural-torsionalbucklingbyMichelII1]whoconsideredthelateralbucklingofbeamsofnarrowrectangularcross-sectionandwhoseworkwasextendedin19O5byTimoshenkol2ltoincludetheeffectsofwarpingtorsioninI-s… 相似文献