Dynamic elastic buckling of a slender beam with geometric imperfections subject to an axial impulse

Results from a numerical investigation of the dynamic buckling of an elasti c slender beam, with initial geometric imperfections, subjected to an inten se axial impulse are presented. The pulse buckling response was numerically modelled via the finite difference and finite element methods. Three comme rcially available software packages were utilized during the investigations : ADINA (Users Manual, ADINA R&D, Inc., 71 Elton Avenue, Watertown, MA, 021 72, USA, September 1990 (http://world.std.com/ similar to adina/).) ANSYS ( Users Manual, Ver. 5.3, Troy Technology Park, 1960 Ring Drive, Troy, MI, 48 083, USA, SAS IP Inc., 1997 (http://www.ansys.com).) and NISA (Users Manual , Ver. 7, Engineering Mechanics Research Corporation, P.O. box 696, Troy, M I 48099, USA, 1997 (ht tp://www.emrc.com).). The analysis demonstrated that only random geometric imperfections would initiate the characteristic expo nential growth of transverse buckling displacements. Accurate modelling of the peak buckling amplitude and modal response required aspect ratios in th e order of 1:1. The finite difference models were consistent with theory. T he performance of quadratic, plane strain finite element models was superio r to that using beam elements. This was related to the inherent curvature r estrictions defined through the Euler-Bernoulli beam element formulation. A buckling criterion based on critical load intensity was investigated. Deta ils on the numerical models, computations and analyses are presented. (C) 2 000 Elsevier Science B.V. All rights reserved.