A PERTURBATION SOLUTION OF FREE VIBRATION OF CYLINDRICAL SHELLS WITH RING-STIFFENERS

In this paper,the free vibration of cylindrical sheel with ring-stiffeners is studied indetail by using the PLK method in singular perturbation and the general Hale’s law, and theformulas calculating natural frequencies of cylindrical sheel with ring-stiffeners areexpressed.Finally,the FEM solution is also given to prove the perturbation solution to beseemly,and this comparison shows that the method yields very good results.     

环向加筋圆柱壳自由振动的摄动解

本文采用奇异摄动中的PLK方法和作者在[13]中所提出的广义Hale定理,讨论研究了带有环向加强肋圆柱壳的自由振动,由此并给出了一个计算环向加筋圆柱壳固有频率的一般计算表达式。为了验证本文解的精确性,文中还采用数值方法对此作了对比,比较结果表明,摄动一阶近似解已达到较好的精度。     

Nonlinear buckling analysis of hyperbolic cooling tower shell with ring-stiffeners

This paper is concerned with a numerical solution of hyperbolic cooling tower shell, a class of full nonlinear problems in solid mechanics of considerable interest in engineering applications. In this analysis, the post-buckling analysis of cooling tower shell with discrete fixed support and under the action of wind loads and dead load is studied. The influences of ring-stiffener on instability load are also discussed. In addition, a new solution procedure for nonlinear problems which is the combination of load increment iteration with modified R-C are- length method is suggested. Finally, some conclusions having important significance for practice engineering are given.The Project Supported by National Natural Science Foundation of China.     

Vibration analysis of moderate-thick plates with slowly varying thickness

In this paper, the flexural vibration analysis of moderate-thick rectangular plates with slowly varying thickness using perturbation method is described, and the explict expressions of free vibration frequencies for arbitrary thickness functions are derived. Finally, several numerical examples have been given and comparisons have been made with other proposed solution techniques. This comparison shows that the method yields very good results, so that this method may be regarded as an alternative effective method for the vibration and buckling analysis of plates and shells.     

求解五弯矩方程式的一种待定参数法

对于弹性支座上的连续梁,可归结为求解如下的五弯矩方程组: GX=F (1)其中为了求解方程组...     

非均匀弹性双曲冷却塔的动力计算

本文分析讨论了工程中钢筋混凝土结构的材料特性,提出了一种考虑非均匀配筋的钢筋混凝土材料本构关系——非均匀弹性本构方程。在此基础上,本文又进一步研究了混凝土出现裂纹后的钢筋混凝土材料本构关系式,提出了一种计算混凝土具有局部裂纹群的钢筋混凝土材料本构方程式。 根据文中所提的本构方程,本文采用轴对称有限单元对双曲冷却塔的动力特性、阵风响应分别作了计算,其数值结果同分别按等效各向同性、正交各向异性所计算得到的结果进行了对比,比较结果表明,这三种模型除了频率比较相近之外,振型和风振系数都有较大的差异。     

钢筋凝混土壳体的非线性分析

本文采用有限元数值方法,分析计算了大型钢筋混凝土壳的几何、物理非线性静力问题。对非线性方程组的求解,文中提出了一种将载荷增量和位移增量相结合的合理方法,保证了在临界点附近迭代法的收敛性。最后,文中通过对实际双曲冷却塔壳的分析,得到了一些对实际工程设计具有指导意义的有益结论。     

VIBRATION ANALYSIS OF MODERATE-THICK PLATES WITH SLOWLY VARYING THICKNESS

In this paper.the flexural vibration analysis of moderate-thick rectangular plates withslowly varying thickness using perturbation method is described.and the explictexpressions of free vibration frequencies for arbitrary thickness functions are derived.Finally.several numerical examples have been given and comparisons have been made withother proposed solution techniques.This comparison shows that the method yields verygood results,so that this method may be regarded as an alternative effective method for thevibration and buckling analysis of plates and shells.     

多变量载荷作用下的结构非线性稳定分析

本文从有限元基本平衡方程出发,首先导出了结构非线性稳定性分析的一般方程,在此基础上给出了一个既简单但又明瞭的临界点类型判别准则。其次,作者引用 Koiter 的渐近分析基本思想,给出了一个用有限元平衡方程形式表达的初始后临界分析的近似方程式。使用这一公式,一方面我们能判断结构在后临界状态的特性(如稳定或不稳定);另一方面我们也能把它作为在临界点处的一个有限元增量解,从而可避免在临界点处一般由于切线刚度矩阵奇异而产生的迭代收敛缓慢或发散。最后,作为本文所建议方法的应用,也给出了二个简单的分析算例。     

NONLINEAR BUCKLING ANALYSIS OF HYPERBOLIC COOLING TOWER SHELL WITH RING-STIFFENERS

This paper is concerned with a numerical solution of hyperbolic cooling tower shell,a class of full nonlinear problems in solid mechanics of considerable interest in engineering applications.In this analysis,the post-buckling analysis of cooling tower shell with discrete fixed support and under the action of wind loads and dead load is studied.The influences of ring-stiffener on instability load are also discussed.In addition,a new solution procedure for nonlinear problems which is the combination of load increment iteration with modified R-C are-length method is suggested.Finally,some conclusions having important significance for practice engineering are given.