Prediction of fatigue crack propagation in bulb-flat by experimental and numerical method

The fatigue crack propagation in the bulb-flat, which is widely used in ship and bridge engineer ing, is one of the basic parameters for structures'fatigue life prediction. In this paper, the shape of a three dimensional surface crack in full-scale bulb-flat was measured and estimated by Nominalization Crack Opening Displacement (NCOD) method. Then the obtained crack shape was used to predict the fatigue crack propagation in the bulb-flat based on the two dimensional Paris formula and the Linear Finite Element Analysis (LFEA) method. Finally, the predicted fatigue crack propagation was verified by the full-scale fa tigue test on a typical ship structure in detail. This method proposed in this paper may provide reference to the definition of failure criterion of bulb-flat.