Investigations on operational transfer path analysis in combination with additional artificial excitation by the use of a physical model

Abstract

This thesis covers the influence on artificial excitation used together with opera- tional data from an engine applied on operational transfer path analysis. Therefore, a physical model was built with two structure-borne sound paths and one airborne sound channel. The history and theory of transfer path analysis is treated briefly and the setup of the model is explained. All paths of the model have been measured individually as well as combined to receive a basis to evaluate the transfer path synthesis results from both operational and combined operational and hammer data. The crosstalk cancellation needed to receive the transmissibilities was performed with different data than the input signal of the synthesis. Three sets of impulse hammer measurements were used to see if artificial excitation is best to be per- formed before the source, at the interfaces or on the individual paths. All impulse hammer measurements were used for two different reference planes to derive mea- surement rules for combined measurements. The results of the thesis indicate that impulse hammer measurements can be com- bined with operational data, if certain paths are calculated insufficiently. Therefore, every path has to be reached and hammer impacts have to be performed in all di- rections at or before the reference sensor. If the source is insufficient to excite all frequencies it can also help to excite the source itself with an impulse hammer.