Simplified analytical model and numerical simulations of finite-disturbance buckling of columns

Phenomenon of finite-disturbance buckling (FDB) is commonly attributed to thin elastic cylindrical and spherical shells and it has been rarely associated with columns. Ziolkowski and Imielowski's, Experimental Mechanics 51(8), (2011) 1335–1345, recent experimental study, revealing appearance of FDB in aluminum columns with slenderness remaining within specific range only, raises questions about its physical sources and mechanism. The main objective of the presented work is to provide a theoretical explanation and quantitative evaluation on the phenomenon of finite-disturbance buckling of columns undergoing elasto-plastic deformation and expressing itself in the form of critical load drop. Elucidation of the issue may have some implications to the hitherto design procedures. The paper presents a coherent analytical model of the phenomenon supported by comprehensive finite element results, compared with experimental data.

► Explanation and quantitative evaluation of FDB phenomenon for short columns is presented.
► Model of FDB is developed through analytical studies and comprehensive finite element results.
► Presented results are compared with experimental data.
► Load drop is associated with the rod's elongation occurring just after buckling.
► This is effect of unsymmetrical distribution of stress increments caused by inelastic buckling.