Research On Abnormal Vibration And Exhaust Noise Control Technology Of A Truck

The vibration and noise problems in vehicles relate with ride comfort and have become an important restriction for its rapid development. The studies on the control of vibration and noise in vehicle have an important significance and practical value.For the research of abnormal vibration and excessive exhaust noise on a truck, a study on theoretical analysis, experimental study and numerical simulation has been done to find out the cause of abnormal vibration of trucks and lack of muffler. And the corresponding solutions have been put forward and validated. The main contents of this paper are summarized as follows:(1) Abnormal vibrate analysis and research for the truck cabThe road experimental of vehicle has been done, and the characteristics of the vibration signal on the cab floor have been studied. Built vehicle vibrate system modal of a truck and performed modal analysis of every sub-system based on modal theory. Then the modal parameters have been got. The result from modal analysis, excitation and response frequency showed that the main reason that cause transverse vibrate of the truck under the velocity of 65km/h was as follows: the excitation from wheel unbalance in this velocity closes to the third-order and the five-order natural frequency of the frame and leaf system. The experiment result showed that the PSD of the cab floor reduce significantly and the ride comfort of the truck is improved after improving the frame and controlling wheel unbalance. At the same time, the comfort in other common speeds is not affected.(2) The research of exhaust noiseThe exhaust frequency spectrum characteristics and insertion loss have been obtained by engine bench test. And the frequency bands to be improved are analyzed. Built the acoustic and fluid finite element model of exhaust muffler, and studied its acoustic and aerodynamic performance. Based on the theory analysis and experimental study, the improvement program is put forward. The numerical simulation of the improved muffler showed that the acoustic performance and aerodynamic performance are better than the original muffler. The product sample pieces are made. It is showed by engine bench test of the improvement muffler that the insertion loss is decreased and the power loss ratio is changed less. The experimental results are consistent with the simulation results very well.In conclusion, according to the engineering problems in the paper, the abnormal vibration and exhaust noise of a truck are improved. And its research and analysis method has theoretical significance and practical value.