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 elastic slender beam, with initial geometric imperfections, subjected to an intense axial impulse are presented. The pulse buckling response was numerically modelled via the finite difference and finite element methods. Three commercially available software packages were utilized during the investigations: ADINA (Users Manual, ADINA R&D, Inc., 71 Elton Avenue, Watertown, MA, 02172, USA, September 1990 (http://world.std.com/ similar to adina/).) ANSYS (Users Manual, Ver. 5.3, Troy Technology Park, 1960 Ring Drive, Troy, MI, 48083, USA, SAS IP Inc., 1997 (http://www.ansys.com).) and NISA (Users Manual, Ver. 7, Engineering Mechanics Research Corporation, P.O. box 696, Troy, MI 48099, USA, 1997 (ht tp://www.emrc.com).). The analysis demonstrated that only random geometric imperfections would initiate the characteristic exponential growth of transverse buckling displacements. Accurate modelling of the peak buckling amplitude and modal response required aspect ratios in the order of 1:1. The finite difference models were consistent with theory. The performance of quadratic, plane strain finite element models was superior to that using beam elements. This was related to the inherent curvature restrictions defined through the Euler-Bernoulli beam element formulation. A buckling criterion based on critical load intensity was investigated. Details on the numerical models, computations and analyses are presented. (C) 2000 Elsevier Science B.V. All rights reserved.