Numéro : 2594 - Year : 2010
Fatigue crack propagation simulation in typical FPSO structures
Nicolas MARCHAL, Bureau Veritas– Direction Commerciale Marine
The FPSOs, acronym for a Floating Producing Storage and Offloading units, are submitted to waves’ excitations. These random stresses can cause crack initiation due to fatigue phenomenon. To preserve the integrity of a FPSO, it is necessary to know the critical areas of the structure and to plan inspections based on the propagation rate of the potential cracks. Thus, this paper presents studies of propagation of fatigue cracks on typical connections of a ship. At first, after modeling the structure and loading model, we determine the crack path through the principal stresses constraints. The crack path found is similar to the crack shape in the ship's structure. Then the simulation of propagation is performed with the software SAPHIRS. This software, based on shell type finite element, uses the method of Spring Line and local technical approach to calculate the intensity factors of stress. The software is able to take into account the interaction of multiple cracks. This technique avoids successive re-meshing all along the crack path. These studies permit therefore to determine the criticality of cracks and frequency of inspections of critical areas
This paper is written in English
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