Fatigue life extension of the lower hopper knuckle connection of a carrier by optimization of the structural arrangement

The present computational study deals with fatigue life extension of the lower hopper knuckle connection at a bulk carrier by modifying properly the structural arrangement of the configuration. It is known across literature that low fatigue life is developed at this location. First, the fatigue life of the original configuration is identified by a detailed fatigue analysis. To extend the fatigue life of the detail, minimization of the stress values which induce fatigue is attained by the process of structural optimization. To this end, the geometric parameters of the detail that affect these stress values are identified and introduced as the optimization problem design variables. The solution of the optimization problem is achieved by coupling a finite element code with a multi-objective optimization code based on evolutionary algorithms. By the final optimal solution set, an appropriate optimal individual is chosen for further examination. The implementation of the optimal solution chosen provided extension of the overall fatigue life of the optimal configuration by 2.9 times, whereas the peak stress value has been identified in a different location in comparison to the original configuration.