Application of Indirect Force Estimation Techniques to the Automotive Transfer Case

In the NVH design optimization of automotive structures, the spectral properties of dynamic forces transmitted from rotating machinery to its housing is of primary interest. This paper describes the application of an indirect dynamic force estimation technique, more commonly known as transfer path analysis, to an operational transfer case.

Through the implementation of an inverse transfer matrix technique, dynamic forces transmitted to a transfer case housing are estimated at a discrete number of locations. This paper describes the experimental and analytical methodology employed for dynamic force estimation as well as statistical techniques for solution optimization.

Good correlation is shown to exist between frequencies of known physical phenomena and estimated dynamic forces for a total of nine (9) operational variations of transfer case speed and torque. In addition, comparison of measured operational acceleration response to acceleration response derived from estimated forces demonstrates moderate certainty in force estimations.