Friction Induced Vibrations of Brakes: Research Fields and Activities

Friction induced vibrations in brakes are a topic of major interest and concern for the automotive industry. The structural vibrations that may occur, as well as the audible noise that can be related to them, may lead to consequences as diverse as driver discomfort, maintenance requirements, and even safety issues. Although friction induced vibrations are known already since the beginnings of friction brake design, a generally accepted consensus on many aspects, like fundamental mechanisms or generic solution approaches, seems still to be debated. The present paper attempts to shed some light on the reasons for these persisting difficulties. A review of the different classes of phenomena appearing is given, which could be understood as an attempt to limit the scope of phenomena considered as friction induced. Research topics and disciplines involved will be identified and a clarification of achievements and unanswered questions will be attempted. Due to the enormous amount of work that has been done on the general topic during the last at least five centuries, and in the context of vehicle friction brakes during at least one century, it is of course not claimed to give an exhaustive and in-depth review of each and any line of thought and investigation. However, by synoptically bringing together the phenomenological as well as the disciplinary points of view, a contribution to explaining remaining difficulties and to addressing open research tasks is attempted.