Stochastic Buckling of Composite Cylinder with Geometric Imperfection and Global Sensitivity Analysis

This paper studies stochastic buckling analysis of an unstiffened composite cylinder with geometric imperfection under axial compression. The effect of random initial geometric imperfections, material properties, ply orientation, and ply-thickness on the buckling limit load of a thin-walled, composite cylindrical shell is presented. The initial geometric imperfections are modeled as the mode shapes of the perfect geometry during the linear buckling analysis (LBA), and the stochastic buckling knockdown factor (KDF) is estimated numerically. Furthermore, a non-intrusive polynomial chaos expansion (PCE) is utilized to perform uncertainty quantification (UQ). To reduce the number of function evaluations required during the PCE building process for UQ, adaptive-sparse polynomial chaos expansion with L1-norm minimization is utilized based on orthogonal matching pursuit (OMP). Finally, global sensitivity analysis (GSA) based on Sobol indices is used to identify the system’s critical parameters. The results showed the uncertainties’ significant effect on the buckling eigenvalues of the structures. Moreover, it showed that it is crucial to account for geometric imperfection and other sources of uncertainty during the design phase to obtain a robust design.