Structure-borne Sound Source and Transfer Path Analysis of coupled Structures using the Example of a Railway Air Conditioning Unit

摘要

Within a research project at the Fraunhofer Institute for Machine Tools and Forming Technology IWU, vibration description methods are applied using the example of an air conditioning unit (AC unit) from a railway vehicle. The AC unit consists of several components, where usually the compressors and fans contribute most to the radiated sound power resp. to the transmitted structure-borne sound into the vehicle. In a first step, forces F and accelerations a under steady-state conditions were measured on each of the six mounting brackets of the air conditioning unit. Afterwards, all of the dominant vibration sources of the unit were investigated individually concerning their contribution at each of their contact points. Finally, knowing the mobilities Y of the contact points between sources and unit enables detailed analysis of the system itself. Moreover, it also indicates "weak points" which have to be avoided according to an improved vibrational behavior of the complete air conditioning unit.