Analytical approach for global fatigue of composite-hull vessels

Multi-axial strain fatigue is a complex subject that is rather a research topic than applied design subject even in isotropic steel material. In a layered and non-homogeneous structure such as the composite hull of a ship, multi-axial fatigue analysis becomes non-realistic and computationally non-feasible to apply in a preliminary design phase. This study presents a pragmatic approach and the associated results developed with the ambition of having fatigue design tools for design review of hull structural components. Furthermore, the validation of such an analytical characterisation would reduce the number of fatigue tests required to be performed for each new design; thereby reducing the duration and expense of the fatigue testing campaign. The study includes two parts – an analytical part (led by Bureau Veritas) where the fatigue assessment formulations are defined, and an experimental part (led by University of Limerick) used to feed the models, support the hypothesis, and validate the results. The focus is set on defining practical tools which can be applied for the global fatigue analysis of composite-hulled ships.