The effect of aspect ratio on the elastoplastic response of stiffened plates loaded in uniaxial edge compression

A numerical study of the effect of aspect ratio on the buckling and collapse behaviour of flatbar-stiffened plates in compression is described. The plate equations are expressed in finite difference form and the solution is obtained using a dynamic relaxation algorithm. Initial imperfections and residual stresses are also introduced in the study. It was found that, for aspect ratios between 2 and 3.5, buckling occurs in the elastic regime, with the panels exhibiting significant post-buckling strength prior to collapse. For aspect ratios between 1 and 2 buckling occurs as the plastic zone increases, followed by rapid unloading as the panel collapses suddenly. The ultimate strength of the panel reduces with increasing aspect ratio, remaining practically constant at higher aspect ratios. The latter is attributed to the initial single half-wave distortion profile that prohibits the formation of the preferred buckling mode.