Analysis Of Vibration Characteristics And Noise Control Technology Of Automobile Exhaust System

With the rapid development of society and the continuous improvement of people’s living standards,cars have become one of people’s daily transportation,and the ride comfort of cars has also become an important indicator for people to buy cars.For automobile manufacturers,improving the NVH performance of automobiles means improving the competitiveness of their products.Therefore,it is of practical significance to study the NVH performance of automobiles.The vibration and noise of the exhaust system are one of the main factors that affect the performance of the car’s NVH,so the work of this article focuses on the car’s exhaust system.This paper studies the noise control of automobile exhaust system.First,for a certain type of exhaust system,its structural parameters were measured,and its three-dimensional solid model was established using the three-dimensional modeling software SOLIDWORKS.Then use the finite element software HYPERMESH to divide the mesh on the basis of the three-dimensional model,establish the finite element model of the exhaust system and import it into the finite element analysis software ANSYS for free modal analysis,and obtain the theoretical parameters.Then the exhaust system is subjected to a free modal test to obtain the test parameters.The results of the two are compared,and it is found that the error between the theoretical value and the test value of each order modal frequency does not exceed 10%,which proves that the established finite element model is reasonable.Then,the influence of different suspension positions on the modal of the exhaust system is analyzed.After that,85pre-selected suspension points were selected on the finite element model of the exhaust system,and the analytic hierarchy process was used to calculate the weight coefficients of each mode shape in the exhaust system vibration,and the average driving degree of freedom displacement method was used.Three best suspension positions were obtained and verified.Finally,the basic principles of active noise control technology are introduced,and an active noise control test platform is built using instruments and equipment such as car audio,power amplifiers,etc.;the characteristics of the LMS algorithm and the FXLMS algorithm are compared,and the 200 Hz sinusoidal noise is used as the primary sound source.The two algorithms were tested,and after comparison,it was found that the FXLMS algorithm has better noise reduction effect;for the noise reduction problem of a certain vehicle,an active noise control algorithm based on FXLMS was written,and two active noise control schemes were designed and respectively The noise reduction test is carried out on four different engine speed working conditions and the car is kept stationary.The results show that the two schemes have good noise reduction effects,and can basically maintain a noise reduction of more than 10 d B under four different engine speed working conditions Effect,through comparison,a scheme with better noise reduction effect is selected.In summary,this article conducted a modal analysis of the exhaust system,optimized its suspension position,thereby improving the vehicle’s NVH performance,and using active noise control technology to achieve the purpose of further reducing the noise in the car.