RCAAP Repository

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

During many years the automobile industry used only experimental techniques to develop its products. However, in the last decades technological advances of computers and the development of sophisticated simulation software provided considerable time and cost reduction associated with the development of new vehicles. From this new point of view, experimental tests are not eliminated instead they are necessary to predict component parameters for model simulation and validation. The use of simulation software helps the engineer in design solution finding as well as its evaluation under different conditions. However, the model must represent the real system behavior with highest accuracy. To do this, experimental tests with a prototype must be accomplished and the results compared with the simulation. In this work, the numerical validation of a short long arm suspension (SLA) model will be compared with a real prototype. The reduced scale prototype was built and experimental tests were conducted for different suspension parameter adjustments. The simulation was made by means of multi-body model using the commercial software ADAMS®. The simulation results shown that the computational model could represent the prototype behavior adequately.

In the offshore industry, the utilization of conventional process of arc welding processes are frequently used to repair structure defects, such as cracks. These repairs are carried out under water to reduce risks of explosion. Under water welds are subjected to hydrogen embrittlement and severe porosity. An alternative is offered by the friction hydro pillar processing (FHPP), which may be regarded as a process in which a hole is drilled and filled with a consumable rod of the same material. Despite its wide applicability, this technique has not been widely investigated. Motivated by the potentialities of this method, an infrastructure for repairing engineering structures by drilling and filling holes was designed and constructed. The equipment was designed with an axial force capacity of 50 kN, and a tangential force limited to 10 kN. The rotational speed was limited to 8000 rpm. The FHPP parameters were completely automated, where by the user has only to give them. To validate the infrastructure repair tests were carried out in plain carbon steel plats. The obtained results showed that a metallic bond between the substrate and the rod was achieved. The system enables to perform experimental tests in order to optimize the friction hydro pillar process parameters.

Among the machining operations, drilling with twist drills stands out as one of the most widely used in the metalworking industry. Although the literature presents a lot of research, surely there is still room for scientific work on the drilling process. This study examines the influence of the drilling cycle (continuous and intermittent - popularly known as "pecker" or " eliminates chip") on the performance of machining of cast iron GH - 190 with HSS twist drills coated with multilayer TiN-TiAlN, diameter 10 mm. The experiments were based on a fractional factorial design 24-1. The trials were organized in two parts, first with the retrieve of the tool of 1 mm and one, two and three stops of the tool. The second part with three stops along the length of drilling and tool retrieves of 1 mm, 3 mm and total. Each test was performed in three runs, one test and two replicas. The end of tool life criterion adopted was catastrophic failure of the tool (collapse). Besides the tool life, the following output variables were also considered: the surface finish, the cylindricity deviation, roundness, thrust force (Fz) and torque (Mz) monitored. During the tests images of the cutting edge, cutting point and margin of the drills were recorded to check the levels of wear. Different cutting speeds (45 m / min and 65 m / min), feed rates (0.20 mm / rev and 0.30 mm / rev) and lubri-coolant conditions (dry, flood and MQF) were used. For comparison purposes, ten plans with eight trials each, were combined and analyzed. The results showed that the drilling cycle affects machinability, depending upon the lubri-cooling system and the number of stops used. The cutting speed, the flood and MQF systems are the variables that most influenced the tool. In general there was a direct relationship between cutting conditions and the output variables: thrust force, torque, surface roughness (Ra and Rz) and geometric deviations (roundness and cylindricity). The action of cutting fluids contributes to better surface quality of machined holes.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Exploration and production of oil and gas mobilize large sums of economic and human resources and, therefore, require a reasonable success perspective. Once an oil-well exploration is analyzed and its viability is demonstrated, the drilling starts. However, even the oil well is initially viable; it can suffer odds events that could stop the exploration. Then, in order to restore the oil production, it is necessary to proceed to the destruction operation, which aims to clean up the well. This operation requires special tools, normally with tungsten carbides, so-called destruction tools. Due to the high costs involved in oil exploration, it is essential that these tools fulfill their functions, i.e., they do not fail and clean up the oil well. Within this context, it is important to assure the quality of manufacturing the destruction tools, which is carried out by brazing process of a stick made of tungsten carbide in a alpaca matrix (alloy of Cu-Zn-Ni). Therefore, this work aims to propose a methodology for accreditation of destruction tools of column parts used in oil wells, through the assessment of consumables, manufacturing process (brazing) and the final tool (simulative test). Computational routines were developed, as well as gravimetric, impact and simulative tests. The results showed that image processing and analyses are effective in the consumable assessment. Gravimetry showed capable of distinguish mass percentage of tungsten carbide and alpaca in the stick (consumable). The modified Izod impact test is a suitable approach for analyzing the fracture shape and local of the brazed deposit. The simulative test highlighted the carbide granulometry and tool rotation that is more appropriated for using during the destruction operation of oil wells.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais