Study Of The Vehicle Acceleration Noise Based On The Transfer Path Analysis

The NVH performance of vehicles is not only an increasingly important factor for potential customers,but also one of the most important issues for major vehicle manufacturers.The noise of the vehicle in the process of acceleration is mainly caused by the engine,and the complex structure and the coupling characteristics of various systems greatly increase the difficulty and workload of vehicle noise control.Therefore,it is of great practical significance to control the interior noise under acceleration.Aiming at solving the acceleration noise problem,the interior structure noise caused by engine excitation is studied with a compact SUV as the research object.Firstly,the transfer path analysis(TPA)test method is used to obtain the TPA data.Secondly,the TPA method is combined with CAE simulation analysis.Finally,the results are optimized based on the CAE simulation and the effectiveness of the theory is experimentally verified.Predicated on the above methodology,the following research is carried out in this thesis:(1)The generation mechanism(the ’source-transmission path-response’ model)and the control method of the vehicle interior noise are described in detail in this paper.Using the spectral analysis theory and test method,the theory and experimental procedure of the TPA method is studied in depth.The advantages and disadvantages of different TPA methods including the conventional TPA,fast TPA,multilevel TPA and operational path analysis(OPA)are compared,and the conventional TPA method is found to have the highest analysis accuracy and data integrity.Therefore,according to the requirement of the TPA simulation and optimization,the conventional TPA method is chosen to identify the main transmission path and obtain the engine excitation.(2)The engine excitation structure TPA analysis model is established,and the vibration data of the excitation points and the corresponding transfer functions are experimentally obtained.The noise curve corresponding to the interior noise is fitted and the contribution from different transmission paths is analyzed.Finally,the transmission path on the right engine mounting is determined to be in need of optimization based on the contribution.(3)Using the inverse matrix method,the force spectrum of the engine excitation is obtained and then loaded into the finite element model to predict the interior noise response.The interior noise prediction curve obtained by virtual transfer path analysis accurately reflects the real vehicle roar problem.IPI(Input Point Inertance)and NTF(Noise Transfer Functions)analyses are conducted on the engine mounting points to verify the TPA analysis and demonstrate that the CAE simulation model is effective.(4)The problematic structures are modified based on the CAE simulation and the peak noise value is reduced.Meanwhile,the stiffness parameter of the right engine mounting is optimized using the energy decoupling method.Test results show that the influence of the engine mounting on the interior noise is largely reduced and the NVH property of the tested vehicle is hugely improved.