Multi-objective robust design optimization of fatigue life for a welded box girder

ABSTRACT

To reduce the scatter of fatigue life for welded structures, a robust optimization method is presented in this study based on a dual surrogate modelling and multi-objective particle swam optimization algorithm. Considering the perturbations of material parameters and environment variables, the mean and standard deviation of fatigue life are fitted using dual surrogate modelling and selected as the objective function to be minimized. As an example, a welded box girder is presented to reduce the standard deviation of fatigue life. A set of non-dominated solutions is produced through a multi-objective particle swam optimization algorithm. A cognitive approach is used to select the optimum solution from the Pareto sets. As a comparative study, traditional single objective optimizations are also presented in this study. The results reduced the standard deviation of the fatigue life by about 16.5%, which indicated that the procedure improved the robustness of the fatigue life.

KEYWORDS:

• Multi-objective robust optimization
• fatigue design
• dual surrogate model
• particle swarm optimization

Acknowledgments

The authors express their appreciation to engineers Jiantao Li and Qi Zhong at Sany Heavy Industry Co., Ltd, for their assistance with the fatigue tests.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors would like to thank the National Key Technology R&D Program of China for support [Grant No. 2012BAF02B01].