Three-dimensional structural design optimisation based on fatigue implementing a genetic algorithm and a non-similitude crack growth law

This paper presents the ‘generalised Frost–Dugdale’ law together with a genetic algorithm in a numerical study of a 7050-T7451 aluminium structure. The design objective is the fatigue life of the structure. Genetic algorithms have rapidly become popular due to their robustness, and the balance that can be achieved between efficiency and effectiveness. However, they have yet to be used in a three-dimensional structural fatigue based optimisation study involving crack growth from Region I. Therefore, a genetic algorithm was developed for use in structural finite element optimisation problems. The proposed structural optimisation procedure integrates geometrical modelling, structural analysis and optimisation into one complete and automated computer-aided design process. This study focuses on a simple benchmark structure, which was termed ‘a through-hole in a rectangular block under biaxial loading’. In this case, it was discovered that the genetic algorithm results resembled the optimal solutions of other optimisation algorithms and thus provides an accurate optimised solution. As a result, this paper illustrates a procedure for the design of light weight structures using fatigue based optimisation in conjunction with a genetic algorithm. This procedure has the potential to be applied to structures with complex structural configurations.