Transfer path analysis and its application in low-frequency vibration reduction of steering wheel of a passenger vehicle

Abstract(#br)The demands on improving the noise, vibration and harshness of passenger vehicles are growing rapidly. Low-frequency vibration of steering wheel is one of the most important factors leading to the discomfort of drivers. This study proposes a systematic analysis methodology to reduce the low-frequency vibration of steering wheel using classical transfer path analysis (CTPA). The theoretical basics of TPA using dynamic stiffness approach and inverse matrix approach are briefly introduced, and then the experimental apparatus and analysis procedures in performing the TPA are introduced. The static forces in the rubber mounts of the powertrain system are calculated, the dynamic stiffness of the rubber mounts are estimated, and the operational forces are determined. The contributions of different transfer paths to the vibration of steering wheel are analyzed and compared, and the predominant causes are identified. The results show that the vibration of steering wheel along the X direction is protruded at the engine ignition frequency, and the vibration of the exhaust system along the X direction contributes most to the vibration because of large frequency response function. The mounting structure of the exhaust system is modified based on modal analysis results using finite element method to reduce the vibration of steering wheel

A Hybrid Lumped Parameters/Finite Element/Boundary Element Model to Predict the Vibroacoustic Characteristics of an Axial Piston Pump

Low noise axial piston pumps become the rapid increasing demand in modern hydraulic fluid power systems. This paper proposes a systematic approach to simulate the vibroacoustic characteristics of an axial piston pump using a hybrid lumped parameters/finite element/boundary element (LP/FE/BE) model, and large amount of experimental work was performed to validate the model. The LP model was developed to calculate the excitation forces and was validated by a comparison of outlet flow ripples. The FE model was developed to calculate the vibration of the pump, in which the modeling of main friction pairs using different spring elements was presented in detail, and the FE model was validated using experimental modal analysis and measured vibrations. The BE model was used to calculate the noise emitted from the pump, and a measurement of sound pressure level at representative field points in a hemianechoic chamber was conducted to validate the BE model. Comparisons between the simulated and measured results show that the developed LP/FE/BE model is effective in capturing the vibroacoustic characteristics of the pump. The presented approach can be extended to other types of fluid power components and contributes to the development of quieter fluid power systems