Yikun Wang

Influence of Localized Pit Distribution and Bench-Shaped Pits on the Ultimate Compressive Strength of Steel Plating for Shipping

This work has developed numerical models simulating steel plate corrosion degradation and presents a series of novel finite element modeling to assess the influence of localized pit distribution and bench-shaped pits, which are often observed in long-term exposures. Four location patterns of one-sided corroded shipping steel plates have been considered, which include both geometric and material non-linearities. Validation of the modeling method is achieved by a thermoelastic stress analysis, which provides the principal stress distribution over the plate surface. The modeling results demonstrate that the frequently detected localized corrosion may reduce the ultimate strength by up to 20% compared to uniformly corroded plate. In addition, bench-shaped pits may further decrease the ultimate strength by up to 14% compared to the no-bench condition with the same degree of pitting.

Corrosion Prognosis: Maritime Structural Performances in Service Environments

For marine platforms, assessing the structural resilience in a corroded condition is vital for both design and maintenance practices. With the development of computational and experimental methods for structural analysis, the accuracy of the structural response prediction relies on a better understanding of the material degradation process. However, a realistic estimate of corrosion is inherently a complex undertaking. Corrosion of even a single form can often involve multiple stages, each of which has different steps across several geometric scales; corrosion systems are often multi-layered and involve geometric complexities; the mechanical factors (stress/strain distributions) could affect the corrosion initiation and kinetics. These complexities have resulted in scientific barriers to the advancement of a corrosion prognosis that forecasts damage accumulation, as well as a computational realization of the corrosion-structural analysis. This paper reviews the numerical and experimental work that the authors have done, including the development of nonlinear finite element models to assess the behavior of damaged steel ship structures, full-field experimental validation, application of the mechano-electrochemical theory and in situ tensile-corrosion tests. It is intended that the outcome of this research will be the establishment of a systematic multi-scale multi-physics experimental and numerical protocol for predicting aged structural resilience.

Experimental investigation into factors affecting the transient flow of fluid through an orifice in realistic conditions

During operations, damage can occur with a resulting ingress or egress of fluid. The incoming water affects the reserve buoyancy and it can also change stability and hull girder loading. During a flooding event it is vital that the flow through the damaged orifice and the movement of floodwater around the structure can be predicted quickly to avoid further damage and ensure environmental safety. The empirical measure coefficient of discharge is used as a simplified method to quantify the flooding rate. In many internal flow applications the coefficient of discharge is estimated to be 0.6 but recent research shows that it can vary considerably when applied to transient flooding flows. This paper uses an experimental setup to investigate how changes to the orifice edges and position within the structure affect the flow. It is then used to investigate the coefficient in a more realistic scenario, a static compartment in waves.