The phenomenon of fatigue of materials is one of the most studied topics in Mechanical Engineering

The phenomenon of fatigue of materials is one of the most studied topics in Mechanical Engineering. The first formal publications made by researchers and scientists referring to the analysis and documents related to this topics appear in the nineteenth century. It has been of great interest to go deep into the study of this anomaly, taking into consideration its impact on the useful life of different mechanical parts built with different materials. Currently, for the diversified industrial field (aeronautical, aerospace, metallurgical, naval and automotive) it represents a considerable percentage the appearance of this type of events that are commonly produced in the machinery and parts of the mechanical components that are subjected to continuous and forced work. These in turn, are daily exposed to the various and sudden changes of the environmental conditions for being a fundamental part in the operation and functionality of the equipment used in the air, sea and Earth.
The automotive industry in general, is one of the most important economic sectors in the world for its revenues; it is a great generator of employment because in addition to the direct labor required, it influences a whole parallel industry of auto parts, so the indirect labor is extremely large as well. We can understand as a general concept that the automotive industry is the set of companies, factories, consortiums and related organizations in the areas of design, development, manufacturing, marketing and sales of all types of automobiles. (1)
By naming this type of industry dedicated to the manufacture of all types of vehicles, this includes all those that are manufactured according to their use, such as light vehicles and heavy vehicles. In this case, large machinery and those vehicles with strategic use and military nature are used according to the governmental interest in order to keep the sovereignty of each country and region. Today, the development of new vehicles and modern aircraft is directly aimed not only to reduce the weight by replacing parts with lighter components and manufactured with recyclable materials, but also to reduce the contamination of the environment. Determining the useful life of the parts and mechanical components used by these large industries is of great interest for engineers and constructors. The necessary studies of the mechanical parts that allow to withstand high mechanical loads and with a better resistance to high temperature ranges at a low cost for the market have become priority of many industries around the world.
The Automotive Industry had its first beginnings in the decade of 1890. The first country in providing the world with a large production of automobiles, was the United States of America. After the Second World War, the United States of America manufactured about 75% of the automobiles world production. In 1980, the United States of America was overtaken by Japan, whom later became the world production leader until 1994. In the year 2006 Japan reached the United States of America again in production and maintained this position until 2009, when the People’s Republic of China, through its great advances in science and technology, opened the commercial space taking the first place, fulfilling until today with a highly competitive world market.
In this research work, the material used to perform the studies corresponding to fatigue failure behavior, is Aluminum Alloy 7055. A description and characterization of its origins, use, applications for the industry in general was made and specifically in the automotive industry as a base component for the manufacture of parts and pieces. Specifically, for the manufacture of transmission cases, brake systems, shock absorbers, cooling system, all for the use of light and heavy vehicles with great strength and durability, taking into consideration the work requirements and competitiveness for world markets.
Next in Chapter 2, we mention the equipment and experimental procedures used, the analysis of macroscopic and microscopic fractures that are reflected from the realization of the tests performed in the laboratory, hardness measurements and data processing methods. Chapter 3 shows the analysis of the fatigue limit of materials, the construction and study of the SN curve, graphs and values contributed of the results of the experiment, later in Chapters 4, 5, 6, it was possible to consider first the analysis of the fatigue fracture, the methods applied to collect the results obtained from the tests, being able to show through the photographic fixation of the experimentally submitted piece, the hardness analysis, the fundamental equations for later making the comparisons of the changes in the material. Graphics are displayed that allow visualizing the behaviors that have occurred in each test applied. Finally after carrying out this investigation, the conclusions and recommendations are made in general about the fatigue behavior of 7055 aluminum alloy materials.