Low-Cycle Fatigue Test of Welded Tubular Joints

Low-cycle fatigue tests were performed for various sizes of X-type welded tubular joint specimens. The relationship between the repeated load and the number of cycles to failure is estimated by modifying the test data based on the Bayesean theorem. The size effect and the influence of residual stress, which is called the annealing effect, are also considered. The statistical approach that is described can be applied to the fatigue test data which are stongly influenced by the scatter of welding defects. In case of low-cycle fatigue of welded tubular joint specimens, the S-N curve can be assumed as a straight line on the regular scales. Concerning the size effect in low-cycle fatigue, the relative strength of welded tubular joint specimens shows a downward trend with an increase in the size of the specimen.