Secondary Buckling of Thin Plates with Initial Deflection

Abstract

It is well known that a thin flat plate undergoes secondary buckling after initial buckling took place and the deflection of the initial buckling mode has been developed. The plates in actual structures are usually accompanied by initial deflection due to welding. So, the influences of initial deflection have to be considered when the secondary buckling strength of plate members in actual structures is evaluated. In this connection, series of elastic large deflection analyses are performed applying the analytical method and the finite element method. In the analyses, symmetrical and non-symmetrical initial deflections are assumed based on the measured results. It has been found that:(1) Although the secondary buckling of a thin rectangular plate with initial deflection due to welding generally takes place in a symmetrical mode, the non-symmetrical components of deflections cannot be ignored in the analysis, since there is an interaction between symmetrical and non-symmetrical components.(2) The initial deflection reduces the secondary buckling strength when it takes place far after the stable deflection mode has been developed. The reduction becomes significant with the increase in aspect ratio of the plate (3) The lower bound of secondary buckling strength increases with the increase in the magnitude of initial deflection, because some components of initial deflection resist the initial buckling deformation to take place.(4) The inplane rigidity of the plate is significantly reduced by the secondary buckling.(5) The collapse mode of plates under compression is influenced by the secondary buckling, particularly near the aspect ratios at which the mode of primary buckling changes.