Assessment of residual ultimate strength for wide dented stiffened panels subjected to compressive loads

The aim of the present paper is to study the influence of a local dent on the collapse behaviour of stiffened panels. A quasi-static nonlinear finite element analysis is used to simulate the production of the local dent which will model the residual stress and the springback effect of the stiffened panels. The effect of residual stress caused by the local dent on the collapse behaviour of stiffened panels is investigated. The material properties used in the finite element analysis have been evaluated by tensile tests. Stiffened panel models with three and two bays in the longitudinal direction are used to prescribe appropriately boundary conditions for the middle bay. The relationship of the maximum indentation load and length of plate are almost linear and the springback displacements converge to a constant with increasing final depth of the dent. The residual stress caused by the indentation affects slightly the ultimate strength of the dented stiffened panels under consideration.