Influence of stochastic geometric imperfection on the ultimate strength of stiffened panel in compression

The initial geometric imperfection is recognized as substantially influential on the buckling behaviour and ultimate strength of stiffened plated structures. Conventionally, the initial geometric imperfection is defined in a deterministic manner, such as a hungry-horse mode, ARE mode or critical buckling mode with characteristic magnitudes. However, due to the uncertainty in manufacturing and in-service effects, the initial geometric imperfection should be better described as a random field. This paper aims to assess the effects of the stochastic nature of geometric imperfection on the ultimate strength of stiffened panel in compression. A probabilistically-based imperfection model developed by spectral representation method is applied to an orthogonally stiffened panel. A Monte-Carlo Simulation enhanced by a Latin-Hypercube Scheme (LHS) is utilized to sample the initial geometric imperfection. A series of nonlinear finite element analyses are completed to calculate the ultimate compressive strength of the case study model. With reference to the deterministic representations, the impact of the stochastic imperfection model is discussed. The present work may provide useful insights for the reliability-based ship structural assessment regarding the uncertainty due to geometric imperfection.