Avenati-Bassi F., Lorea S., Tinti F.

Customer demand for increased vibro-acoustical comfort performances of vehicles, coupled with reduced development time frame, requires a continuous improvement process in the engineering design phase. These needs call for fully comprehensive FEM models, in order to simulate vehicle performances already in the very early stages of the project: for this purpose, a big amount of detailed information is necessary, as the virtual vehicle should be as close as possible to reality and thus complete of trim and equipments. Moreover, being the first target setting and final verification phases of the development process experimentally based, a good numerical-experimental correlation is a milestone. The validated numerical model should be used in an efficient and systematic way in order to outline criticalities, find-out the important transmission paths and optimise the performances: an innovative approach for this goal has been conceived, focussed on total energy distribution and minimisation criteria as a guideline in the selection of crucial structural improvements. The paper fully describes the complete methodology, both in its theoretical aspects and practical issues, as it was applied during a development of a new D-segment car for the emerging Asian market. The virtual vehicle has been realised either by direct or equivalent dynamic modelling and provided with the whole dynamic information coming from the technical specifications or the experimental database . The acoustic cavities have been modelled with their real geometric shapes and volumes and complete of phono-absorbing properties of the different trimmings. Both the local behaviour and the vibro-acoustic coupling of the structure with the internal cavities have been analysed and the newly-conceived methodology has been applied in order to solve different types of criticalities.