Abstract
Copper from vehicles disc brakes is one main contributor of the total copper found in the environment. Therefore, the U.S. Environmental Protection Agency (EPA) and the automotive industries started the Copper-Free Brake Initiative. The pad friction material is essentially composed of a binder, fillers, reinforcing fibres and frictional additives. Copper and brass fibres are the most commonly used fibres in brake pads. There is a need to understand how the contact temperature distribution will change if copper-based fibres are changed to steel fibres. The aim of this work is, therefore, to investigate how this change could influence the local contact temperatures. This is done by developing a multi-scale simulation approach which combines cellular automaton, finite element analysis (FEA) and computational fluid dynamics (CFD) approaches with outputs from inertia brake dyno bench tests of Cu-full and Cu-free pads. FEA and thermal-CFD are used to set the pressure and the temperature boundary conditions of the cellular automaton. The outputs of dyno tests are used to calibrate FEA and CFD simulations. The results of the study show lower peaks in contact temperature and a more uniform temperature distribution for the Cu-free pad friction material.
Highlights
Both the brake pads and discs of disc brake systems wear during deceleration
The wear is higher for the Cu-free material and the wear is higher on the edge of the chamfer due to the higher contact pressure
Secondary plateau formation is higher in braking #30 which is the lower power brake event. This could be explained by that a higher contact pressure results in a higher amount of wear and in a higher wear of the secondary plateaus created. This is in line with the work presented by Wahlström et al [31] who conducted a factorial design to numerically study the effects of brake pad properties on friction and emissions and concluded that the there is a trade-off that depends on the specific wear rate of the contact plateaus between obtaining a sufficiently high stable friction and low emissions
Summary
Both the brake pads and discs of disc brake systems wear during deceleration. Some of the wear will deposit on the ground and some will be airborne as particle emissions [1]. The Copper-Free Brake Initiative has, been started by Environmental Protection Agency (EPA) and automotive industries [4]. The aim of this initiative is to remove or consistently reduce the copper presence in friction materials (called Cu-full materials). A relatively new category of pads called “Cu-free” (or “eco-friendly”) has, been developed, contrary to “Cu-full” pads which contain copper [5,6,7,8,9,10,11,12]. In order to obtain Cu-free pads, Cu-fibres can be changed to steel fibres
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