Numéro : 2636 - Year : 2013
Methodology of quick estimation of cyclic fatigue behaviour in a confined plastic zone: application to welded joints for shipbuilding
Sarah PLESSIS, LBMS – ENSTA Bretagne, DCNS LORIENT
David THEVENET, ENSTA Bretagne
Sylvain CALLOCH, ENSTA Bretagne
Hans MINNEBO, ENSTA Bretagne
Cédric DOUDARD1, DCNS LORIENT
Welded assemblies commonly used in the shipbuilding industry provide many possibilities for the design of complex structures from simple geometric elements. These key elements contribute to the integrity of the structure and are subjected to complex and intense cyclic loading. Welded assemblies contain geometrical discontinuities, which generate local stress and strain concentrations, and more particularly along the welding seam and due to confined plasticity, nucleation of fatigue cracks can occur in these highly stressed regions. Shipbuilding engineering and design department therefore need to have efficient methods to predict the fatigue behaviour of welded assemblies. Elastic-plastic finite element analyses could be performed but since the computational cost is prohibitive, other quick estimation methods were developed. The local elastic-plastic behaviour can be estimated using, for instance the Neuber’s rule but, the lack of accuracy in these methods led to a new approach based on homogenization models which is used in this study. Predictions from this approach will be compared to finite element computations and to experimental results on shipbuilding welded assemblies.