Identification of Influence of Cross Coupling on Transfer Path Analysis Based on OPAX and OTPA in a Dummy Car

In this paper, the cross coupling effect of the vibration paths in a dummy vehicle is investigated by the conventional transfer path analysis (TPA), the operational path analysis with eXogeneous inputs (OPAX) and the operational transfer path analysis (OTPA). The traditional transfer path analysis (TPA) is developed in the beginning of the 1980s at first. It is widely used as a tool for not only NVH troubleshooting but also estimating the transfer path of vibration and noise. Nowadays the TPA has becomes a powerful tool for the vibration source identification in the automotive engineering. TPA requires a lots of test time to process the full data such as the measured operating data and frequency response function (FRF). Based on these disadvantages of traditional TPA, relatively new approaches have developed such as OTPA and OPAX. The OPAX uses parametric models to characterize the operating load and needs a minimum number of extra tests with excitation. The OTPA has the advantage because it request the only operation data for evaluate the contribution of vibration sources. However, there are three limitations in the usage of the OTPA. The study deals with one of three limitations of the OTPA. It is the influence of the cross coupling between several source inputs. The problem of the cross coupling has been discussed with experiment data and presents the method to solve this influence.