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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.

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.

ISO 11439 standards consider 4 types of high-pressure cylinders to storing natural gas for vehicles applications. Among them the type 2, metal-lined hoop wrapped cylinder, is the aim of this work. It describes a numerical model built using ANSYS application to determine stress on the metal liner and on composite material applied on the liner by filament winding process. Using design criterion for laminate composites, the total thickness of the composite layer has been evaluated to get an optimized value. Employing the element shell multilayer of ANSYS 8.1 and a model of the type 2 cylinder, the stress state in the metal liner and in each layer of the composite has been studied.

Brake drums are components designed to dissipate kinetic energy of vehicles, converting it, mostly, into thermal energy. The stress state originated by thermal transients produced by braking cycles may nucleate fatigue cracks and lead the component to failure. The aim of this work is to analyze and compare thermal fatigue strength for brake drums, made in vermicular cast iron, with different design geometry. Firstly, fatigue life has been evaluated for the original geometry. The same analysis has been performed after reducing the thickness of the brake drum. From thermal and structural analisys, via finite element method, temperature evolution and loading history for the component have been obtained. The life of the component has been estimated for the region with the highest probability for crack nucleation by thermal fatigue. The rain-flow method of counting cycles has been applied and Goodman equation has been used to evaluate the fatigue life of the component.

The AISI 41B30H steel is one of the materials used to produce cylinders for storing natural gas for vehicles. These pressure vessels are normally produced by flow forming of a seamless tube of this material and followed by spinning process, a hot forming process that closes the ends of the tube. In this work, the mechanical properties of an AISI 41B30H steel heat-treated in the intercritical region, to produces a dual-phase microstructure of ferrite-martensite have been studied and compared with that of the material in the normalized as-received condition. The determination of quenching temperature within the intercritical region was obtained using computer simulation with THERMO CALC software and these results have been validated by metallographic analysis. The forming properties have been analyzed by means of tensile tests.

The brake drums are designed to convert kinetic energy of the vehicle into thermal energy. The stress originated by thermal transients produced by braking process may nucleate fatigue cracks and lead the component to failure. The aim of this work is to study thermal fatigue life for brake drum made with gray cast iron and vermicular cast iron. The loading transients due to different braking events were determined by thermal analysis, using FEM methods. Stress amplitudes and mean stresses were obtained. The fatigue life of the component has been evaluated and the points with the highest probability for crack nucleation were determined. The highest level of stress was observed in the hoop direction when the brake drum is made in gray cast iron and in the radial direction when it is made with vermicular graphite cast iron.