Optimum design of hierarchical stiffened shells for low imperfection sensitivity

• Published in: Acta mechanica Sinica 2014-06, Vol.30 (3), p.391-402
• Main Authors: Wang, Bo, Hao, Peng, Li, Gang, Zhang, Jia-Xin, Du, Kai-Fan, Tian, Kuo, Wang, Xiao-Jun, Tang, Xiao-Han
• Format: Article
• Language: English
• Subjects: Classical and Continuum Physics; Collapse; Computational Intelligence; Defects; Engineering; Engineering Fluid Dynamics; Fuel consumption; Optimization; Research Paper; Shells; Stiffeners; Structural weight; Theoretical and Applied Mechanics; Weight reduction; 临界屈曲载荷; 代理模型; 优化设计; 加筋; 最佳设计; 灵敏度; 缺陷敏感性; 运载火箭
• ISSN: 0567-7718; 1614-3116
• DOI: 10.1007/s10409-014-0003-3

A concept of hierarchical stiffened shell is proposed in this study, aiming at reducing the imperfection sen- sitivity without adding additional weight. Hierarchical stiffened shell is composed of major stiffeners and minor stiff- eners, and the minor stiffeners are generally distributed between adjacent major stiffeners. For various types of geo- metric imperfections, e.g., eigenmode-shape imperfections, hierarchical stiffened shell shows significantly low imper- fection sensitivity compared to traditional stiffened shell. Furthermore, a surrogate-based optimization framework is proposed to search for the hierarchical optimum design. Then, two optimum designs based on two different opti- mization objectives （including the critical buckling load and the weighted sum of collapse loads of geometrically imperfect shells with small- and large-amplitude imperfections） are compared and discussed in detail. The illustrative example demonstrates the inherent superiority of hierarchical stiffened shells in resisting imperfections and the effectiveness of the proposed framework. Moreover, the decrease of imperfection sensitivity can finally be converted into a decrease of structural weight, which is particularly important in the development of large-diameter launch vehicles.