Numerical Derivation of Buckling Knockdown Factors for Isogrid-Stiffened Cylinders with Various Shell Thickness Ratios

This study is aimed at providing a numerical derivation of the shell knockdown factors of isogrid-stiffened cylinders under axial compressive loads. The present work uses two different analysis models such as the detailed model with modeling of numerous stiffeners and the equivalent model without mo...

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Bibliographic Details
Published in:International journal of aerospace engineering 2020, Vol.2020 (2020), p.1-14
Main Authors: Yoo, Joon-Tae, Lee, Keejoo, Park, Jae-Sang, Sim, Chang-Hoon, Kim, Han-Il, Yoon, Young-Ha
Format: Article
Language:English
Subjects:
Aerospace engineering
Buckling
Cylinders
Defects
Derivation
Design
Equivalence
Launch vehicles
Load
Loads (forces)
Manufacturing
Mathematical models
Numerical analysis
Perturbation
Postbuckling
Stiffeners
Thickness ratio
Vehicles
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Summary:This study is aimed at providing a numerical derivation of the shell knockdown factors of isogrid-stiffened cylinders under axial compressive loads. The present work uses two different analysis models such as the detailed model with modeling of numerous stiffeners and the equivalent model without modeling of stiffeners for isogrid-stiffened cylinders. The single perturbation load approach is used to represent the geometrically initial imperfection of the cylinder. Postbuckling analyses using the displacement control method are conducted to calculate the global buckling loads of a cylinder. The shell knockdown factor is numerically derived using the obtained global buckling loads without and with the initial imperfection of the isogrid-stiffened cylinder. The equivalent model is more efficient than the detailed model in terms of modeling time and computation time. The present knockdown factor function in terms of the shell thickness ratio (radius to thickness) for the isogrid-stiffened cylinder is significantly higher than NASA’s knockdown factor function; therefore, it is believed that the present knockdown factor function can facilitate in developing lightweight launch vehicle structures using isogrid-stiffened cylinders.
ISSN:1687-5966
1687-5974
DOI:10.1155/2020/9851984