Case Studies Involving the Identification of Problematic Impulsive Effects on Vibration Signals

Recently, during the course of different experimental problem-solving activities on automotive vehicles, several examples have been found in which the identification of the cause of a particular vibration problem related to a specific component or subsystem involves detecting the presence of an impulsive effect on measured time signals. The difficulty in identifying such an effect arises due to the fact that the vibrational response signals measured during operation are dominated by relatively high amplitude harmonics which tend to mask the impulsive component. This article describes two case studies for this type of identification problem, a servo-assisted steering system and a front suspension shock absorber strut. Details are included of how, by selecting appropriate measurement transducers, sensor locations and signal processing techniques it was possible to identify the impulsive effects and trace the cause of the problem as being related in both instances to a hydraulic effect due to constricting the flow of fluid.