Research On Road Noise Optimization Of Vehicle Based On TPA (Transfer Path Analysis)

The automobile industry was once a pillar enterprise of China’s industrial production,but auto sales have started to decline since 2018.In 2019,the automobile economy entered a cold winter,some domestic automobile enterprises have applied for bankruptcy protection,and it will become a more cold winter in the automobile industry in 2020.Therefore,in such a fierce market competition,grasping customer demand and attention is the most important production factor for an enterprise.At the moment,the formulation of international and domestic standards for NVH is becoming more and more stringent.Various aspects are involved in the process of automobile production and manufacturing.Performance indicators,for the steering stability,safety,power economy(fuel consumption)that car companies or R & D engineers are mainly concerned about.The recent addition of new four modernizations of hot cars(electrification,intelligence,networking,sharing),which just increase the selling points of car sales,is not the most demanded by consumers.Traditional safety performance and stability performance cannot be intuitively felt by ordinary mass customers.The most intuitive feeling of consumers before buying a car is the vehicle Power economy,interior vibration and noise,and comfort,especially the latter,automotive Division termed NVH(noise,vibration,Harshness),so the vibration noise control car is still the key areas of development of the automotive manufacturing industry.At present,with the development of the new energy vehicles in the word,the horn of traditional fuel vehicles delisting is also sounding.Compared with traditional fuel vehicles,new energy vehicles have a great difference in NVH research and development due to changes in the power system.The way NVH noise is generated in automobiles.It is simply divided into excitation source → transmission path →in-vehicle response.The main excitation sources of traditional fuel vehicles are engine excitation noise and road excitation noise(referred to as road noise).IVCompared with traditional fuel vehicles,new energy vehicles,especially electric vehicle excitation sources have changed.The drive motor replaces the engine.For NVH engineers,the focus of research and development in the future will focus on the impact of road noise on vehicle vibration and noise.This paper combines corporate cooperation projects to improve the low-frequency road noise performance of a pure electric vehicle.By TPA-transfer path and analysis,it analyzes and optimizes the road noise problem that is the biggest impact on the NVH performance of the electric vehicle.It mainly uses a combination of simulation and experiment.The method optimizes the components in the weak area on the problem transmission path to achieve the purpose of reducing the road noise response in the car,and completes the NVH performance index of the preliminary vehicle development.The basic contents of this paper are as follows:1.Obtaining the actual noise curve of the electric vehicle with the LMS test lab determines the road noise problem under the condition of 60km/h rough road at constant speed.And a detailed road noise transmission path is established through the TMS module of the LMS test lab.Analyze the model,and test the transfer function between the connection point of the chassis and the body to the interior response and each connection point in the anechoic room.The transfer matrix of the transmission path analysis is formed.The matrix inversion method is used to determine the effect of the chassis on the body.Input the load,and solve the ranking of the contribution of each transmission path of the noise from the connection point of the chassis to the vehicle body.It is determined that the sound pressure level of the road noise response in the range of 30-60 Hz exceeds the target line,and the main peak points are 30 Hz and 36 Hz.2.Hyperworks is used to create a finite element model of the interior-trim body simulation(including BIW model,acoustic cavity model,and TB model),calculate the TB mode,and test the TB simulation model to determine the accuracy of the simulation model State and test mode,because its simulation error is controlled within1.5Hz,that means the accuracy of the TB model.Then,the load is loaded into the simulation model,and the noise level response of the road inside the vehicle underrough road conditions of 60km/h is calculated.At the same time,the working deformation of the interior-trim body under the conditions of 60km/h rough road is also calculated.The main weakness areas of the interior bodywork were found out,and propose 5 effective optimization solutions are applied to the parts in the weakness area.3.Finally,the effects of all optimization schemes were verified by means of tests:under the condition of rough road 60km/h,the sound pressure drop around the key peak 30 Hz,36Hz exceeded 8dB,the total sound pressure level decreased by 3dB,and the noise pressure on the road inside the car response reaches the goal,and the subjective feeling is obvious.In general,it proves that the method in this paper is effective,and it has guiding significance for the development of other models and the improvement of road noise performance.