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Journals / International Advanced Researches and Engineering Journal / 2021 / Cilt: 5 - Sayı: 3

Knockdown factors for cylindrical shells caused by torsional Mode-I type geometric imperfections under axial compression

Haluk Yılmaz
İbrahim Kocabaş
Pages
419–425
Publication Date
2022-10-19
DOI
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

These expressions provide the minimum and maximum values of knockdown factors for a given imperfection depth, which can be treated as a design tool to ensure safety of the shell structure.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:Geometrical imperfection, which is generally a result of manufacturing process and service conditions, plays a crucial role in load-bearing capacity of shell structures.
📊
Key Findings & Data:Then, geometrically nonlinear buckling analysis with imperfect model (GNIA) is incorporated with LBA in ANSYS Workbench to obtain limit loads of imperfect structures.
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Conclusion & Impact:These expressions provide the minimum and maximum values of knockdown factors for a given imperfection depth, which can be treated as a design tool to ensure safety of the shell structure.
🔬Design:Modeling & Simulation
📍Scope:Comprehensive Sample
⚙️Variables:Axial compression · Cylindrical shell · Finite element method

Abstract

Geometrical imperfection, which is generally a result of manufacturing process and service conditions, plays a crucial role in load-bearing capacity of shell structures. This study presents a numerical study on knockdown factors of cylindrical shells as a result of torsional Mode-I type of geometric imperfections under compressive loads. The deformation patterns obtained from liner bifurcation analysis (LBA) for torsional Mode-I shape are used as a source of geometric imperfection. Then, geometrically nonlinear buckling analysis with imperfect model (GNIA) is incorporated with LBA in ANSYS Workbench to obtain limit loads of imperfect structures. A parametric study is thus performed to investigate the influence of imperfection depth on the load-bearing capacity considering a wide range of cylindrical shell configurations. Local and global buckling characteristics of the imperfect shells are examined and knockdown factors are characterized by three distinct regions as a basis of normalized imperfection depth. For a large number of shell configurations, a scattering of knockdown factors against normalized imperfection depth is given with mathematical expressions evolving lower and upper bounds. These expressions provide the minimum and maximum values of knockdown factors for a given imperfection depth, which can be treated as a design tool to ensure safety of the shell structure.

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Cite This Article

Yılmaz, H., Kocabaş, İ. (2022). Knockdown factors for cylindrical shells caused by torsional Mode-I type geometric imperfections under axial compression. International Advanced Researches and Engineering Journal, Cilt: 5 - Sayı: 3, 419–425. https://ajindex.com/articles/539267

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