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Journals / International Advanced Researches and Engineering Journal / 2021 / Volume: 5 Issue: 3

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

İbrahim Kocabaş(Vocational School of Transportation, Eskişehir Technical University, Eskişehir, Turkey)0000-0003-0600-2034
Haluk Yılmaz(Vocational School of Transportation, Eskişehir Technical University, Eskişehir, Turkey)0000-0002-6750-3708
Pages
—
Publication Date
2021-12-15
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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.
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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

Kocabaş, İ., Yılmaz, H. (2021). Knockdown factors for cylindrical shells caused by torsional Mode-I type geometric imperfections under axial compression. International Advanced Researches and Engineering Journal, Volume: 5 Issue: 3. https://doi.org/10.35860/iarej.891791

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