The application of OTPA and classical TPA for source contribution analysis in a high-speed train

The Operational Transfer Path Analysis (OTPA) and the Transfer Path Analyses (TPA) are experimental techniques to analyse the transmission of structure-borne sound and airborne sound into the train's interior. In OTPA only operational data are used to determine transmissibility functions, while the classical TPA quantifies the operational loads and determines the vibro-acoustic transfer paths to the target position and response quantity. The OTPA is considered to be the faster technique in comparison with classical TPA methods, but also concerns may arise as to whether the captured operational data are sufficient. In this paper the results of an OTPA will be compared with the results of a classical TPA, both performed on the same high-speed train. The results of both analyses for the primary, secondary and even minor source contributions for several operation conditions will be presented. General remarks about the application of OTPA at rail-bound vehicles and the boundary conditions will be made. Based on our experiences applying both techniques on a high-speed train, a comparison in terms of required equipment, measurements, operation conditions and effort will be presented.