局部轴压载荷下薄壁圆柱壳结构的屈曲稳定性研究

Thin-walled cylindrical shells are widely used in in aerospace, petrochemical, nuclear engineering and other fields. The buckling problem of thin-walled cylindrical shells under local axial compressive load has become a prominent bottleneck that restricts the large-scale and lightweight of such structures. This study aims at ensuring the service safety and lightweight design of the thin-walled cylindrical shell structures in engineering. Based on the theory of plates and shells, finite element method, statistical theory and modern measurement technology, the buckling stability of thin-walled cylindrical shell structures under local axial compression load will be mainly studied. Based on the improved differential quadrature method, a numerical model for solving the stress distribution in the shell is proposed. The buckling failure mechanism of thin-walled cylindrical shell under local axial compression load will be revealed theoretically and experimentally. The high fidelity finite element model of thin-walled cylindrical shell subjected to local axial compression load will also be established. The relationship between the local buckling and global buckling will be studied thoroughly and the failure criteria of thin-walled cylindrical shells under local axial compression load will be proposed. The effects of initial geometric imperfections on the buckling of thin-walled cylindrical shells under local axial compression load will be investigated. Then an alternative method of thin-walled cylindrical shell imperfections which can accurately consider the influence of real geometric imperfections is proposed. Finally, the design method of thin-walled cylindrical shell structures under local axial compression load will be established. The achievements will provide a solid foundation for the design and application of thin-walled cylindrical shell structures in national major engineering.

薄壁圆柱壳结构广泛应用于航空航天、石油化工以及核工程等领域，局部轴压载荷下薄壁圆柱壳的屈曲问题已成为制约该类结构大型化和轻量化的突出瓶颈。本项目以保障工程中薄壁圆柱壳结构的服役安全和轻量化设计为目标，从板壳理论、有限元方法、统计学理论以及现代测量技术出发，着重研究局部轴压载荷下薄壁圆柱壳结构的屈曲稳定性，构建基于改进的微分求积法求解壳内应力分布的数值模型，从理论和实验两方面揭示局部轴压下薄壁圆柱壳的屈曲失效机理；建立局部轴压下薄壁圆柱壳的高保真有限元模型，阐明壳体局部屈曲和整体失稳之间的相关性，提出局部轴压下薄壁圆柱壳合理的失效判定准则；探索局部轴压下初始几何缺陷对薄壁圆柱壳屈曲的影响规律，提出能够准确计及真实几何缺陷影响的薄壁圆柱壳缺陷替代方法，建立局部轴压下薄壁圆柱壳结构的设计方法。本项目的研究成果将为国家重大工程中薄壁圆柱壳结构的设计和应用奠定坚实基础。

对于工程中广泛应用的薄壁圆柱壳结构，局部轴压屈曲问题已成为制约其大型化和轻量化的突出瓶颈。项目组针对局部轴压下薄壁圆柱壳结构屈曲行为与设计方法开展研究，深入揭示了局部轴压载荷下薄壁圆柱壳结构的屈曲失效机理，阐明了圆柱壳屈曲行为的影响因素，探明了初始几何缺陷对局部轴压载荷下薄壁圆柱壳屈曲的影响规律，并在此基础上建立了相关设计方法，为工程中大型圆柱壳结构的设计与应用提供了理论支撑与方法保障。主要成果包括：.1）针对局部轴压载荷非连续的数学问题，构建了求解前屈曲阶段壳内应力分布的数学模型，建立并求解局部轴压载荷下薄壁圆柱壳的屈曲控制方程；开展了局部轴压载荷下薄壁圆柱壳试件的屈曲实验，分析不同分布范围局部轴压载荷下圆柱壳的屈曲破坏过程，揭示壳体的屈曲失效机理。.2）建立并验证了局部轴压载荷下薄壁圆柱壳的高保真有限元模型，开展了圆柱壳的局部屈曲和整体失稳相关性研究，结果表明：局部轴压下薄壁圆柱壳失效模式与局部轴压加载范围密切相关，该范围存在临界值使得圆柱壳从局部屈曲向整体失稳转变。.3）弄清了材料性能、结构特征和加载位置等因素对圆柱壳屈曲行为的影响；分析并探明了局部轴压载荷下薄壁圆柱壳对初始几何缺陷及非传统初始缺陷的敏感性、建议取非传统初始缺陷对屈曲载荷的折减系数为0.9。.4）构建了基于Fp-up曲线波谷值外推预测弹塑性屈曲载荷下限的新方法，验证了其有效性和可靠性；建立了理想局部轴压薄壁圆柱壳屈曲载荷快速计算公式，构建了基于屈曲分类的轴压薄壁圆柱壳屈曲载荷折减因子计算模型，证明了局部轴压薄壁圆柱壳屈曲下限设计方法能够给出可靠的屈曲设计载荷，同时具备一定的安全裕度。.项目组在结构力学、机械工程等领域权威学术期刊：《Thin-walled Structures》、《Composite Structures》等发表论文12篇；申请国家发明专利3项、国际专利1项；计算机软件著作权获授权1项；建立的圆筒许用轴向压缩应力计算新方法已纳入国家标准GB/T 150《压力容器》修订版中。