Ultimate Strength of Hull Structural Stiffened Plate with Grooving Corrosion Damage under Uniaxial Compression

Abstract

Grooving corrosion results in a decrease in the ability of the structure to resist external loads. In the present study, a new assessment method was developed to investigate the ultimate loading capacity of stiffened plates with grooving corrosion damage. First, the basic parameters of stiffened plates (including model range, boundary condition, welding residual stress, initial geometric imperfection, and size of finite element) were assumed. Second, the influences of corrosion parameters and geometrical parameters of stiffened plates (such as finite element type, groove width, groove depth, groove depth-to-width ratio, plate flexibility, stiffener flexibility, and number of stiffeners) were analyzed. Third, based on the data analysis from a large number of nonlinear finite element analyses, the ultimate strength reduction formula of stiffened plates was derived. Last, the correctness of the formula was verified by ultimate strength experiment. Introduction Ships are always in the harsh marine environment, and it would inevitably be corroded. The existence of corrosion would reduce the effective thickness of structures and promote the generation of fatigue cracks, brittle failure, and instability damage. Grooving corrosion is a major corrosion form leading to structural failure of the hull structure (Zhang et al. 2017b). Therefore, it is very important to study the ultimate loading capacity of corroded structures to ensure the safety during the total expected life cycle. Corrosion mainly included uniform corrosion and local corrosion. Local corrosion (such as pitting corrosion and grooving corrosion) was relatively complex. For local corrosion, complex corrosion status appears on the surface of the hull structure. Sultana et al. (2015) analyzed the effect of random pitting on the ultimate compressive strength of plates and stiffened plates. They found that the volume loss caused by corrosion resulted in a significant reduction in the ultimate strength of plates, up to 45%, compared with stiffened plates. Huang et al. (2017) derived the ultimate strength reduction formula of pitted stiffened plates by analyzing a large number of nonlinear finite element analysis (FEA) data. Woloszyk et al. (2018) studied the effect of severe local corrosion damage on the strength capacity of stiffened panels by combining finite element with experimental. They found that corrosion not only reduces the thickness of the structure but also increases the surface roughness and affects the mechanical properties.