Medium-high frequency optimization using SEA sensitivity

SEA allows to solve medium-high frequency dynamic problems because only the energy averaged on each subsystem is needed when too many DoF’s are involved and eigenvalues and eigenvectors loose the significance due to high modal density. Using a SEA model, the subsystem energies are controlled by internal loss factors (ILF) and coupling loss factors (CLF), which in turn depend on the physical parameters of the subsystems. In this paper, a previously developed optimisation technique for medium high frequency dynamic problems based on SEA method is recalled and improved by taking into account the contribution of the injected power. In fact, it depends on the external imposed loads and on the mobility of the subsystems, which in turn depends on the physical parameters. A preliminary analysis of subsystem energy sensitivity to CLF’s is performed to save time in looking for the approximate relationship between CLF’s, injected powers and physical parameters. The approach is applied on a typical aeronautical structure: the cabin of an helicopter.