A Study Of The Transfer Path Of The NVH Problem Caused By Vehicle Powertrain

With the continuous development of science and automotive technology, customers have higher and higher demand towards the car’s performance on all aspects.NVH has become one of the most customers’ sensitive subjective feelings of the vehicle overall qualities, drawing more and more public attention.It has become one of the key issues in automotive research to improve the internal environment of the car and enhance NVH performance. Almost half of the noise is caused by the engine, the main source of the car noise. Vibration noise generated by the engine, pours into the car through each path. It is very important to explore the paths through which the noise goes into. The following researches have been done in this thesis:1 .To establish the finite element analysis model of vehicle TB bodyThe finite element models of the body decoration model and cavity model are established in order to verify the accuracy of TPA test. Then the problems have been found out, and suggestions for improvement have been put forward through the modal analysis.The model for subsequent simulation of vehicle interior noise vibration has further been supplied.2. To set up TPA model under excitation of powertrainThe powertrain vibration transmits into the body through the suspension, subframe,and the exhaust hook, causing vibrating body panels. Based on this, the noise model from the powertrain to the interior structure has been established. Then the number and location of the incentive and indication points have been determined, providing guidance for the test.3. Analysis of vehicle interior noise based on transfer pathAccording to the test results the main sources of noise inside the car have been analyzes from the three aspects the acoustic transfer function, excitation load and path noise contribution. The most significant transmission path has been recognized, providing valuable guidance for the car noise optimization.4. Comparison between CAE model and actual calculationThe noise vibration in the vehicle is simulated when the load spectrum obtained by the experiment is input into the finite element analysis model. Compared with the actual measured data, the accuracy of the experiment is verified.Making the domestic car as the research object, powertrain transmission path caused by the interior structure noise as the focus, this thesis has established the finite element models and test analysis model from powertrain to body structure vibration and noise. After the actual test, inputting the load spectrum into the CAE model and comparing the simulation of noise with the actual noise the accuracy of modeling has been verified. This study has significant guidance value in the noise transfer path identification from the powertrain to the body in the stage of vehicle design and development and automotive interior structural-borne noise control.