Fatigue strength evaluation of Q460 weld joints based on energy dissipation

Traditional temperature-based fatigue strength prediction method, fail to reveal the irreversible energy dissipation behind the fatigue evolution. For the fatigue strength evaluation of Q460 welded joints, a new fatigue strength prediction method, which is based on the energy dissipation of different load levels that exists the turning point, was proposed, i.e. maximum slope method. The energy dissipation was firstly established based on the obtained real-time thermographic data of the specimen surface, and then the energy dissipation value of Q460 welded joints were calculated. Based on the theory of the energy dissipation turning point exists when the load level increases, the energy dissipation was set as an index for rapid fatigue strength estimation. To verify the accuracy of the developed model, the fatigue strength value estimated by the maximum slope method was compared with the predicted value by the traditional bi-linear and staircase methods. The results show that a good agreement is reached between the predicted fatigue strength by the maximum slope method and the traditional bi-linear and staircase methods, and the errors are 0.04% and 4.76%, respectively, which may provide a certain reference for fatigue strength prediction of welded joints.