A Study on Fatigue Strength of Welded Structure by means of Large Scale Model Test

Large scale model tests have been now increasingly attempted for the study on fatigue strength of welded structures. Main advantages of the use of large scale model are the possibility to confirm directly the fatigue behaviour of total structure.The authors carried out a series of full scale model fatigue tests on a slotted part of ship hull structure. Much efforts are exerted to detect the crack initiation and to pursue the crack propagation during the test. An approximate analysis of crack growth was attempted by a fracture mechanics approach. It is noted that the crack growth behaviours are much influenced by various factors such as defects or distortion of structure induced by the fabrication, redistribution of stress among adjoining structural members, etc. Empirical formulas are obtained to estimate crack initiation life and failure life of total structure.