Suppression of Friction-Induced Oscillations Through Use of High-Frequency Dither Signals

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

PI: Kenneth A. Cunefare, The Georgia Institute of Technology Proposal number: 01001122 Proposal Title: Suppression of Friction-Induced Oscillations Through Use of High-Frequency Dither Signals Project Abstract: This research project investigates the suppression of friction-induced oscillations through the use of high-frequency dither signals. The primary application of this research effort is that of brake squeal, which is a self-excited vibration that afflicts most braking systems. Brake squeal has been an elusive problem to solve because it involves an interaction of multiple brake components. This project builds upon research conducted on Georgia Tech's brake squeal dynamometer, which demonstrated that a high frequency dither in the brake pressure could effectively eliminate squeal. This dither force, supplied by means of a piezoceramic actuator, used frequencies beyond the audible range, thus silencing the brake system. This research project aims to understand more fully how dither suppresses brake squeal and how to develop more effective dither-control strategies. The proposed work uses a combination of analytical and experimental techniques. Nonlinear mathematical models of brake systems and subsystems will be developed and validated against experimental observations. The experimental program will explore the use of alternative dither signals as well as feedback to enhance performance and robustness. The influence of dither on mean braking torque will also be assessed. This work promises to have a significant impact in a variety of industrial and scientific applications. Brake squeal-related warranty claims impose a high cost upon the automotive industry. Additionally, brake manufacturers must currently make design compromises in the selection of brake pad materials, compromising on materials that are less prone to induce squeal. Therefore, a low-cost, simple technology that permits improved braking performance while reducing development and warranty costs would yield substantial benefits.