ICSV 14 Cairns • Australia 9-12 July , 2007 1 DISC BRAKE SQUEAL : PROGRESS AND CHALLENGES
Brake squeal noise has been an ongoing concern with automotive brake systems since their inception. It is generated by the vibration of an unstable vibration mode of the brake system, usually with the brake rotor acting as a loudspeaker. The squeal noise that is of concern usually falls into a frequency range from 1 to 16 kHz. Although there is often not any degradation in the braking performance, most customers tend to interpret brake squeal noise as indicative of a defective brake. Furthermore, with improvements made in interior noise and comfort levels in vehicles, brake squeal noise has become an increasing source of customer dissatisfaction and is a major contributor to warranty cost. Research into predicting and controlling brake squeal has been conducted since the 1930s and despite significant research efforts in the past 2 decades, brake squeal still remains a challenging problem that is begging for a better understanding of its generation mechanisms and better methodologies for countermeasures other than empirical approaches. Brake squeal is a transient phenomenon and is highly dependent on geometries of brake components, complex interface conditions between components and material properties that are functions of both temperature and pressure. In this paper, recent developments in understanding and controlling brake squeal noise will be reviewed and challenges that remain to be met are discussed.
FRICTION-INDUCED NOISE AND VIBRATION OF DISC BRAKES
Abstract Several noise excitation theories have been proposed in the literature. These theories are found to be unsatisfactory for explaining the noise excitation phenomenon. In this paper, we propose a simple mechanical impact (hammering) model for brake noise generation. This model is independent of friction variation during the period of decreasing sliding speed.
Self‐Determination, Wellbeing, and Threats of Harm
David Rodin argues that the right of national-defence as conceived in international law cannot be grounded in the end of defending the lives of individuals. Firstly, having this end is not necessary because there is a right of defence against an invasion that threatens no lives. However, in this context we are to understand that ‘defending lives’ includes defending against certain non-lethal threats. I will argue that threats to national-self determination and self-government are significant non-lethal threats to the wellbeing of individuals that can justify lethal defensive force. Therefore the end of defending individuals can ground a right of national-defence against a ‘bloodless invasion’. Secondly, Rodin argues that defending lives is not a sufficient condition for military action to be national self-defence, because humanitarian intervention is military action to defend individuals, and such action is in deep tension with national self-defence. I will argue that a reductive account, grounded in claims of need and threats of harm, can justify principles of both intervention and non-intervention on the same grounds; that is, protecting the wellbeing of individuals.