FATIGUE DAMAGE ASSESSMENT OF SHIP STRUCTURES BASED ON THE LONG-TERM DISTRIBUTION OF LOCAL STRESSES

Article type: Research Article

Authors: Soares, C. Guedes | Garbatov, Y. | von Selle, H.

Affiliations: Unit of Marine Technology and Engineering, Technical University of Lisbon, Instituto Superior Técnico, Lisboa, Portugal | Germanischer Lloyd, Hamburg, Germany

Abstract: The paper addresses the evaluation of the fatigue life of ship structures based on a probabilistic approach that considers the stochastic nature of the ocean environmental loading and the service profile of the ship. The method is based on a linear spectral analysis of the stress range response. The local stress range response transfer functions are obtained by using a three-dimensional finite element model. The response process for each short-term sea state is modelled by a Rayleigh distribution. The long-term response period and long-term stress range distribution are then determined and are fitted as a Weibull distribution. The Palmgren-Miner linear cumulative damage model is applied. An example calculation is presented for a tanker and the influence of several scatter diagrams on the fatigue life of structural details is examined.

Journal: International Shipbuilding Progress, vol. 50, no. 1-2, pp. 35-55, 2003