Structure borne noise characterization of an air generation and treatment unit (AGTU) for a train by using blocked forces method

Interior noise is a challenge for Rolling Stock manufacturers in the search for a comfortable travel experience. To achieve interior noise levels respecting customer requirements, it is necessary to allocate noise and vibration targets to the different train equipment. Airborne source characterization is quite standardized in the railway industry but it is not the case for structure borne sources. An air generation and treatment unit has been installed on a supplier's test rig, a full structure borne characterization has been performed for three different kind of boundary conditions. Rotational degrees of freedom have been also considered thanks to a specific instrumentation. Blocked forces have been obtained thanks to advanced signal processing and computations; they have been then validated via comparison with direct vibration measurements. The novelty of the work presented is the full validation of the methodology for a real train equipment including all possible degrees of freedom and in the close collaboration between rolling stock manufacturer, supplier and academia. The learnings from this work will help to establish new standards for the methodology of structure borne noise characterization of equipment. The work presented here has been performed in the frame of European research project FINE1 in the context of the Shift2Rail JU.