基于模态缺陷的受压球壳屈曲特性研究

Research on buckling behavior of the spherical pressure hull considering initial imperfections

针对受压球壳非线性屈曲过程,对含初始缺陷受压球壳的稳定性进行研究。根据EN1993-1-6(2007)规范,给出不同制造等级壳体的等效缺陷值计算方法;基于线性特征值分析的模态构型给出初始缺陷的分布。利用非线性有限元弧长法对球壳受压失稳过程进行数值模拟,得到屈曲前后球壳变形情况及全过程载荷-位移曲线。计算一致缺陷模态法和N阶缺陷模态法对应的球壳屈曲临界载荷,结果表明,受压球壳对缺陷较敏感,承载能力随缺陷值增大而降低;一致缺陷模态法计算便捷,在工程应用上具有合理性,N阶缺陷模态法考虑高阶模态缺陷构型,结果更加全面,可以为工程中缺陷结构稳定性设计提供参考。

When the stability of a spherical pressure hull being is analyzed,nonlinearity has to be considered as well as the influence of initial imperfections.According to European Standard EN1993-1-6(2007),a method for calculating equivalent imperfection magnitude of different fabrication tolerance quality classes is proposed.The distribution of imperfections is determined based on the mode form of liner bifurcation analysis.By means of a nonlinear finite element method,the stability of a spherical pressure hull is simulated numerically.Deformation of spherical pressure hull before and after buckling is investigated and load-displacement curve is acquired.The critical buckling loads from consistent mode imperfection method and N-order eigenvalue imperfection mode method are compared.It is shown that a spherical hull is an imperfection-sensitive structure and the stability decreases with the increase of imperfection magnitude.Consistent mode imperfection method is convenient and reasonable in engineering applications,while N-order eigenvalue imperfection mode method considers the influence of higher-mode imperfection and produces more comprehensive results which can provide a reference for the stability design of imperfect structures.