Prediction of fatigue crack initiation for welded joints dedicated to shipbuilding applications

Ship structures are usually built by using welding process and are submitted to some variable and complex loadings. The welding process induces specific geometries at the weld toe where local stress concentrations are generated and also creates various mechanical properties in the heat affected zone. Accordingly, welded joints could be a critical area for fatigue damage. In a previous work, a methodology to predict fatigue life has been developed and tested on butt-welded joints. To go further, the present work focuses on more complex assemblies in order to validate this strategy and be able to estimate the fatigue life of representative ship structures. First, the methodology consists of the elastic shakedown study of the structure and then of a post-treatment which predicts the fatigue crack initiation. A comparison between experimental and numerical results is proposed in order to present the accuracy of the proposed strategy to predict fatigue life time of welded assemblies typical of shipbuilding applications.