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The friction materials of the drum and disk brakes correspond to one of the most complex materials applied to automotive industry, however, little is known about how this type of material reacts under wear conditions. The aim of this work is to understand the effects of loads and temperatures on the topology of brake's friction materials under wear regime. For this, brake friction material specimens were subjected to wear tests on which procedure was based on the SAE J661 standard. The tests consisted on a sequence of braking and cooling intervals, where friction material specimens were pushed against a rotating drum with controlled velocity. Different test temperatures and normal loads were set. From these tests, the mass loss of each specimen was measured. In order to understand the topological aspects of the materials tested, an optical microscope and confocal microscope were used.

Great numbers of studies in sliding wear phenomena use the wear rate to quantify material losses. However, in more recent works, some authors have been tried to characterize the wear phenomena by means of the energy dissipation between the contact surfaces of the bodies. The aim of this work is to create an analytical model capable to relate the total energy dissipated by a friction material during a bench wear test and data collected directly in a vehicle brake, in order to predict the durability of this component in service life. To attain this aim, the concept of specific wear volume, SWV, is adopted. The specific wear volume is the relationship between the material wear volume and the energy dissipated during a sliding wear process. In addition, a method to calculate the energy dissipation on friction materials is presented.

The higher is the volume of automated transmissions for high load capacity commercial vehicles in the market, the higher is the necessity to develop auxiliary systems capable to reduce the wear of the clutch disc during start-ability performance in slopped plans. The Hill Start Assist System, HSA, is compounded by a set of components in the brake system, disposed in such a way that provides to the driver the possibility of starting to run with comfort and safety by the actuation of the service brakes, without overheating the clutch system and simultaneously avoiding the undesirable effect of composition roll-back. For this, it is only necessary that the vehicle be equipped, besides automated transmission, Anti-lock Braking System, ABS, and an active traction control in, at least, one of the drive axles.

In engineering development, simulation methods are frequently used to perform thermal and mechanical stress components analysis. In brake systems, where the components are exposed to mechanical and thermal loads, the numerical analysis is very helpful. Once a numerical model for brake assembly is available, it will be possible to understand the effects of successive brake applications on the temperature distribution in drum brake’s friction materials. This is a fundamental aspect to determine, for instance, the thermal stress distribution which is related to the warming and cooling of the brakes. In this work, an analytical solution to calculate stabilized temperature was used to establish a heat flux through a pneumatic S cam drum brake’s friction material applied to a numerical model in a finite element analysis.

In engineering development, simulation methods are frequently used to perform thermal and mechanical stress components analysis. In brake systems, where the components are exposed to mechanical and thermal loads, the numerical analysis is very helpful. Once a numerical model for brake assembly is available, it will be possible to understand the effects of successive brake applications on the temperature distribution in drum brake's friction materials. This is a fundamental aspect to determine, for instance, the thermal stress distribution which is related to the warming and cooling of the brakes. In this work, an analytical solution to calculate stabilized temperature was used to establish a heat flux through a pneumatic S cam drum brake's friction material applied to a numerical model in a finite element analysis.

1 Commercial vehicles have been more and more equipped with more powerful engines allowing considerable increase in size and load capacity. With this increase in capacity, it becomes important to evaluate the efficiency of the brake system to ensure vehicle safety during transportation of people and materials. Braking efficiency of a vehicle is significantly affected by the heat generated by friction between stationary components and rotors. This heat raises the temperature of the components in brake assembly reducing the friction coefficient at the interface between brake lining and drum. Once the friction coefficient is reduced, the braking torque decreases. As consequence, it may cause undesirable scenarios such as braking performance loss due to overheating, tire burst, hub grease melting, brake lining failure, thermal cracking, geometric distortions and brake locking.