Browse Publications Technical Papers 2015-01-2692
2015-09-27

Real Scale Dyno Bench Study on the Relation between Kinetic Energy Dissipation and Friction Material Wear 2015-01-2692

The nature of braking friction is extremely complex and a deeper understanding of the physical mechanisms that govern the energy dissipation at the interface of friction pairs is an important tool to create an even deeper knowledge of tribological behavior of friction material. Friction brakes need to transform kinetic energy into heat: a complete knowledge of thermal effects during this process in every brake component is an essential part of brake design.
As referred to brake pads, the analysis of dynamometer testing data highlighted experimental evidence related to thermo-mechanical effects, such as the different wear resistance capabilities of material classes (NAO and Low Steel). As is well known in the industry and already published, we observed that tribological characteristics are not constant under all testing conditions and they strongly depend on temperature being the direct consequence of kinetic energy dissipation. The aim of this work is to explain the relation between wear and energy for different types of friction materials.
We developed a group of dyno-testing procedures which investigate the relation between wear rate and energy through different ways of dosing kinetic energy and power density. Testing parameters are defined at the interface between the pad and the disc, in order to produce results unconstrained from a specific brake design.
Different friction mix concepts show characteristic wear behavior that can be described by mathematical functions. Wear of mixes with Low Steel characteristics are sensible only to the amount of kinetic energy dissipated while NAO-like mixes show a more complex dependence on velocity, deceleration and pressure.
A tribological characterization of brake materials from an energy point of view has been started by using innovative dyno-testing investigation techniques. We can point out that there's a complex relation between compositions and tribological characteristics. Thanks to this testing procedure wear can be mapped using a representative two dimensional surface defined by energy-related variables in a 3-D space.

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