High frequency optimisation of an aerospace structure through sensitivity to SEA parameters

Classical (FEM, BEM) structural optimisation techniques fail to solve medium high frequency dynamic problems because too many DoFs are involved and eigenvalues and eigenvectors loose the significance due to high modal density. Using a SEA model, the subsystem energies are controlled by (coupling) loss factors, under the same loading conditions. In turn, coupling loss factors (CLF) depend on physical parameters of the subsystems. The idea is to determine an approximate relation between CLF and physical parameters that can be modified in the structural optimisation process, for instance, by using Design of Experiment (DoE). Starting from this relation, an optimisation problem can be formulated in order to bring the subsystem energies under prescribed levels. A preliminary analysis of subsystem energy sensitivity to CLF can be performed to save time in looking for the approximate relationship between CLF's and physical parameters. The approach is applied on a typical aerospace structure.