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This and the next 5 images are from:
Bo Wang (1), Kaifan Du (1), Peng Hao (1), Caihua Zhou (1), Kuo Tian (1), Shanshan Xu (2), Yunlong Ma (2) and Xi Zhang (2)
(1) State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China
(2) Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China
“Numerically and experimentally predicted knockdown factors for stiffened shells under axial compression”, Thin-Walled Structures, Vol. 109, pp 13-24, December 2016, DOI: 10.1016/j.tws.2016.09.008
ABSTRACT: Stiffened shells in launch vehicles are very sensitive to various forms of imperfections. In this study, the imperfection sensitivity of a 4.5 m diam isogrid stiffened shell under axial compression is investigated. The measured imperfection, NASA SP-8007 and several types of assumed imperfections, including eigenmode-shape imperfection and dimple-shape imperfections (produced by the single perturbation load approach (SPLA) and worst multiple perturbation load approach (WMPLA)), are introduced into FE model to predict the knockdown factors (KDFs), respectively. Then, the buckling test of this full-scale stiffened shell under axial compression is carried out to validate the above numerical approaches. It can be found that the KDF predicted by the WMPLA is very close to the test results, while the ones predicted by eigenmode-shape imperfection and NASA SP-8007 are extremely conservative. Besides, the measured imperfection and other assumed imperfections are proven to be risky, because these methods overestimate the actual load-carrying capacity. Finally, it can be concluded that the WMPLA is a potential and efficient approach to predict KDFs in the design stages for future launch vehicles.
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