South and Southeast Asia Brake Conference and Exhibition 2020

Key Role of Thermomechanics on the Friction Brakes Performance

Prof. Philippe Dufrenoy - University of Lille, France

Temperature is a major parameter in the braking system design, related to friction and wear performance and material integrity. However, temperature cannot be dissociated from the corresponding contact localizations induced by thermomechanics. Thermal dilatations inevitably lead to contact localizations closely related to wear and material transformation. Beyond the temperature, it is the knowledge of contact localization mechanisms that is major in understanding performance.

Recent improvements in numerical simulations and thermal instrumentation allow for better determination of contact localizations, both from the point of view of observation (experimental instrumentation) and prediction (thermomechanical modeling).

Examples of applications of these improvements will be presented concerning the reduction of wear by modifying thermal localizations; the improvement of the prediction of squeal thanks to the knowledge of these localizations; and the influence of these localizations on particle emission. These results show that a better consideration of thermomechanical mechanisms is instructive and a vector of performance improvements of braking systems.

On Formulation of Brake Friction Materials and Their Performance

Prof. Peter Filip - Southern Illinois University in Carbondale, Illinois, USA

Brake friction materials are relevant part of friction brakes. These complex composites, typically consist of numerous constituents, which are combined to obtain the required performance. Their formulations are usually optimized with respect to the i) friction level and its stability, ii) wear, and iii) minimized susceptibility to “friction-related noise and vibration” during brake engagements, as well as iv) environmental aspects and v) costs

The most recent shift in transportation industry towards regenerative braking has certain effect on the required properties and formulation philosophy of friction materials.

A review of the most relevant polymer matrix composites, currently used in automotive industry, their relevant properties and selected testing scenarios will be followed by discussion of the most current trends reflecting the necessity to combine regenerative and friction brake applications.

Physics of Stick-Slip: Impact of Friction Vector Rotation

Prof. Ken Nakano - Yokohama National University, Japan

Stick-slip is the typical self-exited vibration appearing in sliding systems, which is caused by the negative dependence of frictional force on slip velocity. Recently, it has been found that in an extended single-degree-of-freedom sliding system, the in-plane angular misalignment (referred to as the Yaw Angle Misalignment (YAM)) produces a considerable positive damping, and therefore provides a practical method to suppress stick-slip [see: https://youtu.be/Swwa3dO3MuE]. This YAM effect, which needs no additional mechanical devices and no viscoelastic materials, has been confirmed experimentally and numerically. Besides, the YAM effect has been also confirmed in various types of sliding systems (e.g., an extended two-degree-of-freedom sliding system with in-plane anisotropy and in-plane asymmetry [see: K. Nakano et al., Facta Univ Ser Mech Eng, 17, 113-124 (2019)]), and some applications to mechanical devices have been examined. In this presentation, with experimental evidence obtained by a novel apparatus, it is shown that the YAM effect is originated from the friction vector rotation, which is invisible from the conventional point of view.

Brake Emissions

Prof. Georg Ostermeyer - Technical University of Braunschweig, Germany

Emissions are becoming more and more the focus of public attention. If there have been problems about emissions for thousands of years, they are increasingly seen as a health problem, but also as a climate-changing element. Every day, new sources of particulate matter are found in our society. At first, we only looked at emissions from engines and minimised them. Now brake and tyre wear are also important sources of traffic emissions.

This lecture wants to show the way of traffic emissions into the environment locally and globally and in particular to trace the role of brake dust. The current state of research in Europe focuses on the measurement of brake dust as accurately as possible on highly upgraded brake test benches. There are also initial research approaches that aim to predict the generation of wear dust from boundary layer dynamics as well as investigations into how the wear dust reaches the environment.

The lecture presents recent results of wear-sensitive boundary layer dynamics of brake linings, novel highly complex city simulations as well as first results of multiscale swarm measurements. For the first time, real wear dust dynamics, in particular from braking in a city, can be simulated. These are essentially influenced by local weather events. The importance of such information is demonstrated by current traffic control systems and their often limited effectiveness in minimizing particulate pollution.

The lecture concludes with an overview of current measures regarding brake technology that change particulate matter exposure and records the as yet unresolved questions on the interaction with microplastics in the environment.

The Triggering Mechanism of Brake Squeal and Vibration Focusing on the Effect of Surface Topography

Prof. Ho Jang - Korea University, Korea

A systematic approach to reduce the brake noise and vibration is introduced based on the fundamental understanding of the stick-slip produced at the sliding interface during brake applications. Various material properties, including stiffness and interfacial strength of the brake friction material, are considered to assess the noise propensity of brake friction materials. Particular attention is given to the topography of the sliding surface and its influence on the triggering energy of the brake noise and vibrations. The experimental evidence of the root cause for the brake pads with high noise propensity is substantiated by molecular dynamics simulations