# Investigation of the Volvo Powertrain Rig Structural Dynamic Response

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Abstract In the development process of a new powertrain, its vibration performance (among others) must be tested. This is done by vibration measurements in special powertrain rigs. Influence of the rig on the measurements can be determined by investigating the rig dynamic behavior. The task, performed in this document, comprises the following items: •Measurement on the rig and then extracting the response and consequently the modal model •Applying simplifications in the rig model in order to get an applicable model for Finite Element (FE)simulation •Performing a FE modal analysis •With this model perform a Finite Element (FE) modal analysis •Measurement and simulation correlation •Presenting the final adjusted FE model which well represents the dynamic response of the rig •Performing substructuring techniques on the results from the FE modal analysis to get the harmonic response; when the engine is mounted to the rig The modal testing step comprises two measurement setups. The first set is done on a so called free-free rig from which the data is used for tuning the FE model. The second set is on a grounded rig which is used for verification of the updated FE model. The experimental modal analysis is based on Impact Hammer test but also a shaker excitation is used to confirm the precision of the results. In order to verify the correlation between analytical and experimental model, Modal Assurance Criteria (MAC) is applied. Tuning the model is done through a trial and error process in which several parameters e.g. element types and joints stiffness are adjusted. With use of two substructuring techniques, CMS and SEREP, the engine is mounted to the rig and the harmonic response of the nodes of interest is extracted. These results are useful for designing engine mounts and its suspension characteristic. From this outcome the influence of rig on the measurements can be interpreted. Regarding the results, a very good verification between theoretical and experimental model is achieved. The final conclusion is that the rig will not affect the measurement on the engine side unless the displacement of the engine mount is the matter of interest. Key words: Modal testing, Experimental modal analysis, Harmonic response, MAC, SEREP, Substructuring, FEM, Modal analysis.

**Nyckelord: **Modal testing, Experimental modal analysis, Harmonic response, MAC, SEREP, Substructuring, FEM, Modal analysis

Publikationen registrerades 2009-04-27. Den ändrades senast 2013-04-04

CPL ID: 93039

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