具有非轴对称几何缺陷的双曲旋转壳应力分析

本文探讨了分析具有非轴对称几何缺陷的双曲旋转壳的一种近似方法,在这种方法中,缺陷的影响是由虚构的载荷模拟的.并提出了在非轴对称载荷作用下,使用该方法分析具有鼓包形缺陷壳体时的一种有效的算法.这种方法既分开了各种曲率误差对于内力和力矩的影响,又体现了它们之间的相互作用,避免了在非轴对称载荷下所需的重复运算,并能在一个仅有轴对称分析能力的程序上实现.本文用该方法分析了受自重载荷和风载荷作用的,具有鼓包形缺陷的双曲冷却塔,并同时用一个特殊的有限元程序直分析了缺陷塔.通过数字结果的比较,检查了等效载荷法的精度及适用性.

Stress Analysis of Hyperbolic Shells of Revolution with Non Axisymmetrical Geometric Imperfections

In analyzing hyperbolic shells of revolution with non-axisymmeteric imperfections, an approximate method based on simulating the effect of imperfections by the application of fictitious normal pressure loading on the perfect shell is investigated. In the analysis of a shell of revolution with a bulge-type imperfection under non-axisymmetric loads, an efficient algorithm of applying the method is developed; the effect of individual curvature errors on stress resultants and couples are separately considered, while the interactions among various curvature errors are properly treated in the analysis by an iterative procedure. This algorithm avoids repeated analyses for non-axisymmetric loads and may be implemented with a purely axisymmetric analysis capability.A hyperbolic cooling tower shell with a bulge-type imperfection is analyzed under dead load and wind load conditions by the equivalent load method. A direct analysis of the imperfect shell is also made by a specialized finite element program. Through numerical studies, the accuracy qnd applicability of the equivalent load method are examined.