An asymptotic lower bound dynamic buckling estimate for imperfect systems under impact loading

regular perturbation procedure is presented for the determination of lower bound dynamic buckling loads of discrete dissipative or nondissipative imperfect structural systems under impact loading. The procedure is based on the energy criterion for establishing the lower bound dynamic buckling estimate of autonomous systems without solving a set of differential equations of motion numerically presented by Kounadis and his associates. Attention is focused on the effect of imperfections on the lower bound estimate. As an expansion in terms of fractional powers of imperfection amplitude, the lower bound dynamic load is constructed by using an inverse expansion of the aforementioned procedure. Application of the procedure is demonstrated by two examples. (C) 1998 Elsevier Science Ltd. All rights reserved.