Numerical Analysis of Plate Buckling Under Uniaxial and Biaxial Compression: Effects of Geometry, Imperfections, and Shell Modeling

Abstract

The buckling response of plates is governed by their geometric and material characteristics, loading conditions, and initial imperfections, while its numerical prediction is also influenced by modeling assumptions. Using finite element simulations in ANSYS Mechanical APDL, this study investigates the effects of shell reference surface position, through-thickness integration scheme, initial geometric imperfections, plate slenderness, aspect ratio, and loading condition (uniaxial or biaxial compression) on the elastic and elasto-plastic buckling behavior of plates. The shell reference surface position had a negligible influence on critical buckling loads but reduced ultimate loads by up to 57.72%. The evaluation of shell thickness integration schemes showed that three integration points are sufficient for elastic analyses and five for elasto-plastic simulations. Plate slenderness governed the development of post-buckling reserve, whereas aspect ratio became increasingly important under biaxial compression. Plates with lower slenderness exhibited ultimate loads up to 42.44% below the corresponding critical loads, while slender plates developed post-buckling reserves reaching 78.04%. The influence of biaxial compression was strongly dependent on plate aspect ratio, with ultimate load reductions reaching 84.78% compared to uniaxial compression. A strong interaction between aspect ratio and imperfection sensitivity was observed, with variations in ultimate load due to imperfection amplitude decreasing from 41.11% in plates with low aspect ratios to less than 5% in elongated plates. The results contribute to a better understanding of the interaction among modeling assumptions, plate geometry, initial imperfections, and buckling mechanisms under uniaxial and biaxial compression.