Application of a modified donnell technique for the determination of critical loads of imperfect plates

Abstract

Methods existing for the determination of critical loads of plates which exhibit a stable postbuckling behavior, like the Southwell method, inflection point, stiffness reversal, Donnell extrapolation method and others, yield inconsistent results. This is mainly due to the fact that the behavior of a plate depends strongly on its initial geometric imperfection and boundary conditions. A numerical study was carried out to examine the behavior of imperfect plates subjected to in-plane loading. The investigation was aimed at determining the effects of initial geometric imperfection magnitude, boundary conditions and gravity on the behavior of the plate, thus developing a consistent method for the determination of the critical load corresponding to a plate once its behavior is provided either by tests or analytically. The present approach is based on application of a modified version of the Donnell method which yields the critical load as well as the initial geometric imperfection of the investigated plate. The numerical studies involved intensive use of the ADINA code for application of the proposed approach to experimental and analytical data and comparison with experimental results.