ABSTRACT
This chapter evaluates the uncertainty of local strain and fatigue crack initiation life of welded joints subjected to axial loading under plane strain condition. The elastic-plastic finite element method is employed in the uncertainty analysis and treated as the reference method in the model uncertainty analysis. Uncertainty analysis implies that the physical variables considered are subjected to natural variability and should be treated as random variables. In addition to the uncertainty due to the randomness of the physical variables, it is also necessary to deal with the model uncertainty involved in the mathematic models used in the analysis. In order to assess the model uncertainty of the estimation methods, it is necessary to compare the results of the methods with the predictions of a more sophisticated one or with experimental results. Combining the local strain amplitude and the strain-life curve, the uncertainty of the fatigue crack initiation life can be predicted, according to the local strain approach.
