An energy-based fatigue life estimation and optimization of an electric mining dump truck welded frame

In consideration of uncertainties of material fatigue characteristics caused by the dimension size and manufacturing process, an interval strain energy density method for assessing fatigue life of welded structure was presented in this paper. Based on the limit experimental data, the data sequence was expanded by the least squares method to obtain the upper and lower strain energy density life curves of welded joints. Then, the cyclic stress and strain were calculated through the nonlinear finite element analysis for the electric mining dump truck welded frame structure, whose accuracy was testified by the mine road surface test data. The interval fatigue life at possible fatigue failure positions was estimated. In order to extend the life span of the frame and achieve its lightweight, a multi-objectives optimization design was conducted, based on the Kriging surrogate model. The optimal solution was acquired by the non-dominated sorting genetic algorithm. The results showed that the lower bound lifetime of welded frame was bettered from 5.63 years to 14.97 years while its weight reduced by 12.58%.