Structural stability and reliability of cylindrical shells under axial compression based on random field of geometric imperfections
Final Report Abstract
In this research project, axial compression tests were performed on steel cylindrical shells of two different sizes and materials. The test facilities and measurement systems used to investigate geometric imperfections, buckling load and buckling behaviors have been developed and implemented. A 3D laser scanner was used to measure the geometric imperfections of the cylindrical specimens before testing. The scan data was analyzed using Fourier series analysis to extract coefficient matrix and simulate the uncertainty, allowing the random generation of initial geometric imperfections. Furthermore, the deterministic part of the coefficient matrix was almost the same for the different sample types measured with similar values of r/t-ratio. In this project, the bearing capacity under axial pressure and its statistical characteristics of cylindrical shells were analyzed using numerical methods in the commercial FE program Abaqus®. The geometric imperfections identified in the 3D scans or randomly generated with proposed approach were defined by a distance-weighted interpolation procedure and automatically incorporated into the numerical model. To enhance computational accuracy and avoid the use of resource-intensive dynamic methods, the buckling load analysis was performed using the N-R method accompanied by eigenvalue analysis. Experimental and numerical results indicate that numerical analysis based on non-intrusive SFEM, combined with Fourier representation using the half-wave cosine approach, effectively analyzed the axial bearing capacity and its statistical distribution for cylindrical shells. Through statistical analysis and combined with the Maximum Entropy fitting method, the statistical distribution characteristics of the buckling load of two different cylindrical shell specimen types were analyzed. The results show that the obtained buckling load distributions are more biased towards right-skewed statistical distribution functions such as Weibull distribution or extreme value distribution, especially in the right tail. Additionally, exemplary reliability analyses were conducted. Accurate predictive analysis of the axial bearing capacity and its statistical distribution can provide safer and more economical shell design and verification methods.
Publications
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Buckling Analysis of Cylindrical Shells using Stochastic Finite Element Method with Random Geometric Imperfections, in: The International Colloquium on Stability and Ductility od Steel Structures, 14.-16. Sep. 2022, University of Aveiro, Portugal.
Z. Li, H. Pasternak & K. Geißler
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Experiment‐based statistical distribution of buckling loads of cylindrical shells. ce/papers, 6(3-4), 1816-1820.
Li, Zheng; Pasternak, Hartmut & Geißler, Karsten
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Von der Punktwolke zum numerischen Modell – Laserscanning von Stahlbauteilen/From the point cloud to the numerical model – Laser scanning of steel structural components. Bauingenieur, 98(12), 410-420.
Li, Zheng; Zhang, Qiulei; Erlemann, Raphael; Geißler, Karsten & Pasternak, Hartmut
