Effect of initial geometric imperfections on dynamic ultimate strength of stiffened plate under axial compression for ship structures

Abstract

Compared with static loading condition, the initial geometric imperfection has a significant influence on dynamic ultimate strength, which can greatly change the failure mode and also ultimate capacity. In previous studies, only the 1st buckling mode of plate is usually considered as the initial geometric imperfection. However, it might not trigger the dangerous failure mode and also cannot give the lowest estimation of dynamic ultimate strength. In this paper, the stiffened plates used in ship structures are chosen as the study object. The dynamic action is assumed as a load with impact velocity at the plate short edge along axial direction. The effect of initial geometric imperfection with higher buckling modes is analyzed. Based on validation of the experiment results, a general procedure is offered for considering initial geometric imperfection in dynamic ultimate strength analysis. Then, the influence factors, including imperfection shape, plate slenderness ratio and impact velocity are discussed detailly. At last, a simple formula for dynamic ultimate strength evaluation of stiffened plate is proposed. The conclusions in this paper can provide a guidance for dynamic ultimate strength calculation and ship rules modification.