Research The Matching Of Power-train On NVH Performance With The Method Of Transfer Path Analysis

The vehicle is a complicate vibration-acoustic system. It contains several subsystems and each of them has a unique NVH feature. The powertrain system is one of the most important system in vehicle. Interior noise is the most easily observable problem in the vehicle, and the noise caused by powertrain has drawn much more attention of customers and engineers. The matching problem of powe r train not only has an influence on the acceleration performance and the economic performance but also on the NVH performance. In this paper, I take a passenger vehicle for example. Form the view of the NVH performance, I have done some research about pow ertrain matching using the method of TPA(transfer path analysis). The main research as following :1.Study the vibration resource and vibration performance of the powertrain. As we all know that the powertrain is the main cause of interior noise. Passing th rough mounts, the vibration of powertrain will deliver to the vehicle structure. And because of the acoustic-structural coupled theory, the vibration of vehicle structure will cause interior noise finally.2.Measure the main parameters of the powertrain to build a multi-body simulation modal. I have done a series of K&C simulation analysis compared with test result. The K&C result shows that the multi-body simulation modal has a high accuracy and reliability.3.Build the whole vehicle FEM(finite element met hod) modal. I have done mode analysis on the FEM modal, and the result shows that it is fit with test mode result which means the vehicle FEM modal is accurate. I perform NTF(noise transfer analysis) with the vehicle FEM modal.4.Perform bench test on the multi-body simulation modal after loading torque on the crankshaft of the engine. The torque is measured based on a real engine, and the simulation condition is same with test. After the bench test, the excitation information of chassis key points have been obtained.5.After the multi-body simulation modal bench test and the FEM modal NTF analysis, I already get the two kinds of results with will be used in TPA. To complete TPA, I use Hypergraph software which include a special TPA module. The TPA result shows that the stiffness of leaf spring is too large which cause the interior noise problem. So I decided to reduce the stiffness to lower the interior noise.