A transfer matrix model for analysis of noise and vibration in automotive power steering systems

Abstract

Noise and vibration generated in automotive power steering systems significantly influence the sound pressure level measured in the passenger compartment and other disturbances such as steering wheel shudder. To address these problems, a distributed parameter, transfer matrix model of a complete power steering hydraulic transmission line was developed and implemented on a personal computer. The model includes not only the axisymmetric viscous fluid mechanics, but also the fluid–structure interaction created by the three-dimensional nature of the bends and twists in the tubing, and structural supports. The computations account for 14 state variables throughout the line. Computational results show that the effectiveness of devices such as expansion hoses with or without coaxial tuning cables, employed to reduce structurally transmitted noise and vibration, is limited by the complex coupling between fliud and structure. In fact, proper use of hoses, bends, and structural supports can attenuate noise and vibration and potentially eliminate the need for special devices. Use of this computational model could reduce the amount of experimental testing required to evaluate these systems. [Work supported in part by NSF.]