Structural optimisation of a composite aircraft frame applying a particle swarm algorithm

In this paper a heuristic optimisation technique for the maximisation of weight specific elastic deformation energy of CFRP z-frames used in aerospace applications is investigated. Therein, the focus was on the simultaneous consideration of mixed discrete and continuous variables. For that purpose a parametric finite element model was established. In that discrete laminate stacks and continuous geometry parameters were used for structural optimisation. In order to solve the non-linear unconstrained optimisation task, a particle swarm optimiser was selected and applied. Convergence was achieved after a reasonable number of function evaluations. within the solution space, a structural layout of the z-frame was identified being the best solution with respect to the optimisation objective. While the deformation energy appeared to be flange width dependent, the corresponding frame weight showed a strong relation to the applied laminate stacks. The majority of the suggested solutions exhibited similar response with respect to the overall deformation. Prior to structural failure, flexural-torsional buckling was the governing deformation mode.