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yes / Maintaining appropriate levels of disc-pad interface temperature is critical for the overall operating effectiveness of disc brakes and implicitly the safety of the vehicle. Measurement and prediction of the distribution and magnitude of brake friction interface temperatures are difficult. A thermocouple method with an exposed hot junction configuration is used for interface temperature measurement in this study. Factors influencing the magnitude and distribution of interface temperature are discussed. It is found that there is a strong correlation between the contact area ratio and the interface maximum temperature. Using a designed experiment approach, the factors affecting the interface temperature, including the number of braking applications, sliding speed, braking load and type of friction material were studied. It was found that the number of braking applications affects the interface temperature the most. The real contact area between the disc and pad, i.e. pad regions where the bulk of the kinetic energy is dissipated via friction, has significant effect on the braking interface temperature. For understanding the effect of real contact area on local interface temperatures and friction coefficient, Finite Element Analysis (FEA) is conducted. It is found that the maximum temperature at the friction interface does not increase linearly with decreasing contact area ratio. This finding is potentially significant in optimising the design and formulation of friction materials for stable friction and wear performance.

Intersection crashes account for over one-third of all crashes in the U.S., and 39% of these result in injury or death. As part of a larger effort to develop and evaluate in-vehicle countermeasures to reduce the number of intersection-related crashes, haptic warnings and a combined haptic/auditory warning were explored and compared to combined visual/auditory warnings. The first phase of this study determined which haptic brake pulse warning candidate most often resulted in the driver successfully stopping for an intersection. Five brake pulse warnings were tested (varied with respect to jerk, duration, and the number of pulses). Participants receiving the haptic warnings were 38 times more likely to stop at the intersection than those receiving no warning and 7.6 times more likely to stop than those receiving a combined visual/auditory tone warning. The 600ms-3 pulses condition was advanced to the second phase because it provided the longest warning and had a more favorable subjective rating; it was then combined with an auditory verbal warning (urgent "STOP"). This phase determined whether the added verbal warning resulted in differences from the haptic warning alone. Although the warning was activated 7.62 m (25 ft) closer to the intersection in the second phase than in the first phase, there were no significant differences for the reaction times and distance to stop bar. Participants receiving the haptic plus auditory verbal warning were also 1.5 times more likely to stop than those who received the haptic warning alone. Overall, this study shows that haptic warnings show promise for warning drivers of impending intersection violations. Guidelines for haptic intersection warnings were developed, including a recommendation that haptic warnings be combined with auditory verbal warnings for increased warning effectiveness. / Master of Science

No / Hot spots are high temperature thermal gradients and localisations that are circumferentially distributed on a disc surface which can occur during heavy duty braking. Vibrations and noise can be triggered by hot spotting as well as damage to the disc surface. The experimental investigations suggest that the trigger condition and distribution of hot spots are related to the disc geometry, especially for ventilated discs. To investigate the effects of geometry and structure of a ventilated disc on hot spotting, a 3D finite element model was established. A fast simulation method of hot spotting in 3D was implemented in the model to enable a parametric analysis to be performed more efficiently. The results were validated using experimental data from a laboratory dynamometer.

The paper overviews the modes of vibration of the principal component parts of a brake and their contribution to system instability during noise generation. It is shown that both in-plane and out-of-plane vibration is present and that both can be related to the vibration of the pad. It is further shown that the pad and its region often provide a solution or 'fix' towards noise prevention and it is this area that forms the focus of this investigation. The collective evidence, proposals and associated theory are applied to real brake case studies when it is demonstrated that disc/pad interface 'spragging' may be the source of brake noise. Measurements of the position of the dynamic centre of pressure (CoP) support the theoretical predictions that a leading CoP induces brake noise. Design proposals are suggested that may be applied early in the design phase as a means to reduce the propensity of a brake to generate noise.

yes / To achieve a better solution of disc brake heat transfer problem under heavy duty applications, the accurate prediction of transient field of heat transfer coefficient is significant. Therefore, an appropriate coupling mechanism between flow field and temperature field is important to be considered. In this paper, a transient conjugate heat transfer co-simulation disc brake model has been presented in order to improve the accuracy and feasibility of conventional coupled FE and CFD method. To illustrate the possible utilizations of this co-simulation method, a parameter study has been performed e.g. geometric, material, and braking application. The results show the advantage of the co-simulation method in terms of computing time efficiency and accuracy for solving complex braking heat transfer problem.

no / Hot spots are high thermal gradients on the disc surface during brake events which can cause the undesired phenomena of thermal judder and drone. The origin of hot spotting has been presented by various theories such as Thermo elastic instability (TEI) and progressive waviness distortions (PWD). However, majority of the numerical models based on these theories mainly concentrated on solid disc rather than ventilated disc which is the most commonly used nowadays. According to the experimental work done by the authors, disc geometry factors such as vents and pins also have correlations with hot spot distribution; these phenomena are difficult to be predicted analytically. Thus a convenient 2D asymmetric finite element simulation has been performed in order to obtain the correlations observed in experiments. Further parameter studies investigated factors such as uneven initial temperature, vents, pins and pad length. The results have been correlated with the experimental data and demonstrate the contribution of geometric factors in the generation of hot spots and hot judder.