考虑缺陷作用的弹塑性屈曲加筋柱壳设计

Structural design of elastic and plastic buckling stiffened shells considering effects of imperfections

对于加筋柱壳等薄壁结构,轴压承载力对不同结构形式表现出不同的缺陷敏感性,寻找低缺陷敏感度的结构设计形式具有重要的研究意义.首先以分别发生弹性和塑性屈曲的两个直径3m的正交加筋柱壳为例,研究了不同幅度双曲母线形状对两者承载力的影响,发现双曲母线外凸和内凹会分别提高两种加筋柱壳的轴压承载力.然后以特征值屈曲模态和单点凹坑两种缺陷为例,对具有不同幅度双曲母线的加筋柱壳开展了缺陷敏感性分析.结果表明,对于两种加筋柱壳结构均可以通过适当幅度的外凸双曲母线形状降低缺陷敏感性,为提高运载火箭加筋柱壳的可靠性储备提供了一种易实现的结构方案.

For thin-walled structures, such as stiffened shells, collapse loads show different imperfection sensitivities, and this enhances the significance of finding the designs with low imperfection sensitivities. Based on two orthogrid stiffened shells with a diameter of 3 m （elastic and plastic buckling, respectively）, the effects of amplitudes of hyperbolic generatrix shapes on the collapse loads of two models are firstly investigated. It is found that the outward and inward hyperbolic generatrix shapes can increase the collapse loads of two models. Then, the imperfection sensitivities of two models with varying amplitudes of hyperbolic generatrix shapes are studied in detail based on eigenmode-shape and single dimple imperfections. Experimental results indicate that the outward hyperbolic generatrix shapes are capable of reducing the imperfection sensitivities of two types of stiffened shells, which are expected to provide a realistic design, aiming at increasing the reliability margin for stiffened shells in launch vehicles.