Estudo do comportamento em fadiga de uma chapa de aço microligado, grau API 5L X70

In engineering, for correct designing the structural components required for cyclical stresses, it is necessary to determine a limit of resistance to fatigue, which is the maximum amplitude of the applied tension under which the fatigue failure does not occurs after a certain number cycles. The marine environment is hostile, not only by the high pressure, corrosion, but also by low temperatures. Petrol Production units, composed of the risers (pipelines connecting the oil well to the ship), are dimensioned to remain installed for periods of 20 up to 30 years, and must therefore be prepared to support various efforts, such as tidal, wind currents and everything that is related. This paper focuses on a study on the fatigue behavior of microalloyed steel, API 5L Grade X70, used to transport oil and gas by pipelines. For analysis, we obtained the curves S-N (stress vs. number of cycles) using laboratory data collected from cylindrical longitudinal and transverse specimens used in axial fatigue test in accordance with ASTM E466. The tensile tests and microhardness were performed to characterize the mechanical properties of the samples, and it was found that the values meet the specifications of the standard API 5L. To characterize microstructurally the material, it was also made a metallographic analysis of the steel under study, and the origin of the fatigue crack was investigated with the support of a scanning electron microscope (SEM).

Avaliação de fração volumétrica de austenita retida e martensita em aço trip 800 utilizando três métodos diferentes

In the second half of the last century the automobile industries suffered from the petroleum crisis caused mainly by the wars in the Middle East. These crises led the automakers rethink their vehicles. One of the most important events after that was the adoption of new steels by the industry. One example is the TRIP steels (Transformationinduced plasticity). It is known that the macroscopic behavior of a material is strongly dependent on its microstructure and therefore the quantitative metallography is important to understand and relate the material properties to its microstructure. In this work, different specimens of TRIP steels were etched using LePera reagent. The obtained images were analyzed using digital processing. Using the ImageJ software the methods threshold and watershed were studied as well as a comparison with the ASTM E562 standard. The methods were compared and finally the morphological characteristics and volumetric fraction of the retained austenite and martensite phases were analyzed. The results showed that the threshold led to a higher number of identified grains with lower mean area and total area fraction than the watershed method and ASTM standard

Rerrefino de óleo lubrificante usado

The lubricant oil used in engines of internal combustion must be, periodically, changed. Its mainly function in the engines is to reduce the friction between the pieces, but its presence also promotes the cleanness and the refrigeration of the equipment. These attributions, at the end of some cycles of operation, make the oil to be dirty, that is, full of contaminating substances such as water, gasoline, diesel, additives, oxidized hydro-carbons and rests of metals, not being recommended, therefore, its discarding in the environment. Thus, all the used lubricant oil that leaves the automobiles engine has been thrust, waiting for a solution. The pollution generated by the discarding of a ton of used oil per day in the soil or in the rivers is equivalent to a domestic sewer of 40 thousand of people. The indiscriminate burning of the used lubricant oil generates significant emissions of metallic oxides, besides other toxic gases, like the dioxin and sulphur oxides. In this context, the mean objective of this essay was to effectuate the rerrefine of the used lubricant oil, aiming the increase of its life cycle and consequently contributing for the reduction of the environmental pollution. According to the used process, it was possible to get a rerrefine oil, of good quality, which physicistchemistries properties are in compliance with the norms of NBR and ASTM

Caracterização de compósitos produzidos por VARTM para aplicações aeronáuticas

In recent years the aeronautic industries has increased investment in areas of technological research aiming at materials that offer better performance, safety, weight reduction and fuel consumption. For this reason the most studied materials are polymeric materials, due to their higher mechanical strength and higher stiffness. This work evaluated characteristics of two composite laminates produced from the same process, but they differed only in regions where the resin was injected and the vacuum position. The composite laminates were SC-79 resin reinforced with glass fiber fabric (plain weave) processed via VARTM. For this reason the material was subjected to mechanical tests such as: tensile, and fatigue following standards ASTM D 3039 and ASTM D 3479, respectively. The latter was observed the S-N curve. It was performed the ultrassonic C-scan analysis to check impregnation of the fiber. Considering that the process was the same for the two laminates, with small variations in the injection and in vacum ports, it was expected to find similar characteristics

Metodologia de determinação das curvas de probabilidade de falha S-N-P para uma liga de aluminio submetida a diferentes tratamentos termicos de solubilização e precipitação

The approach of the subject matter in this work relies on the fact that the reliability of methods for performance analysis of materials proves critical for the result. This work focused on the development and presentation of the methodology for lifting probability curves for fatigue test (SN) according to standard E739, this focus is justified by the fact that the results in fatigue test show considerable dispersion making it difficult to reading and interpretation of data, this dispersion arises because the phenomenon of rupture is strongly influenced by internal characteristics of the material, we can then have much data ranging from test to test. Thus we set out originally for a brief study of aluminum alloys in question, as well as the treatments to which they were subjected. We also studied the behavior of materials when subjected to cyclic loading, which configures process of fatigue failure, and even fatigue test method in question. This statistical analysis is based on the ASTM E739 standard, so its contents was studied in detail so that we could present in detail the methodology and raise SN curves for different aluminum alloy 7012 subjected to fatigue test. Data were collected from tests conducted in the department of materials from two samples of aluminum alloy 7012 solubilized and precipitated by different time intervals and assayed temperature fatigue-type traction-compression, these data were then analyzed and used to survey curves using the base as E739. After lifting the curve analyzed the characteristics of the test samples and their correlation with the test results. We confirmed the effectiveness of the method of statistical analysis by ASME E739, which allowed the reading of data without this method would be very difficult to have a reading and comparison of the results for the two types... (Complete abstract click electronic access below)

Diagnóstico geoambiental e avaliação de risco à saúde humana para uma área industrial contaminada por hidrocarbonetos localizada no município de Paulínia (SP)

This paper deals with a case study of assessing risk to human health, with the study area of an industrial site in the city of Paulinia (SP) contaminated by oil, which is disturbing situation that occurs in the state of Sao Paulo, which represents risks for human health, as toxic and carcinogenic potential of petroleum products. As an essential foundation for risk assessment, a Geo-environmental diagnosis of the region was made, posing as historical information of the area and accidents, regional geology and hydrogeology, characterization of contaminants and affected media, contaminant transport and data on potential receptors and pathways. Because of the detection of contaminants above the intervention values CETESB (2005) it was possible to proceeded to quantify risks to human health and the determination of maximum acceptable concentrations for no damage to health, using the methodology and software RBCA Tier 2 (ASTM , 1998) and Spreadsheet Risk Assessment recently published by CETESB. The results showed the risk to the health of industrial workers and regular employees of civil works (both on site) for ingestion of groundwater and inhalation of vapors indoors.

Comportamento fractal de superfície da zona de estiramento em aço 300M temperado

Fracture surfaces are the fracture process marks, taht it is characterized by energy release guieded by failure mode. The fracture toughness express this energy em stress and strain terms in pre-cracked samples. The strectch zone is the characteristic region forms by the transition of fatigue fracture and final fracture and it width demonstrate the relation with failure energy release.The quantitative fractography is a broadly tool uses in failure surfaces characterization that it can point to a material’s aspect or a fracture process. The image processing works like an investigation tool, guinding a lot of studies in this area. In order to evaluate the characterization effectivity and it respectivity studies, it used 300M steel that it was thermal treated by an aeronautical process known and it characterized by tensile test and energy dispersive spectroscopy (EDS). The tensile test of this material, made by ASTM E8, allowed the head treatment effectivity confirmation, beyond of mechanics porperties determination. The EDS confirmed the material composition, beyond of base the discussion about fracture mechanism presence. The fracture toughness test has also made, that it works to obtain the fracture surfeaces studies below self-similarity and self-affinity approaches. In front of all the exposed it was possible to conclude that the fractal dimension works like a study parameter of fracture process, allowinf the relation of their values with changes in thickness, which interferes directly in material’s behaviour in fracture toughness approach

Comportamento fractal de superfícies de fadiga em ligas aeronaúticas

Fracture surfaces express sequences of events of energy release with crack propagation in metal alloys, the evolution of topographic features can indicate the lines of load action, failures during the use or processing. The quantitative fractography is an important tool in the study of fracture surfaces, because it allows their interpretation and characterization. In order to evaluate the effectiveness of the characterization of fracture surfaces grounded on concepts such as selfsimilarity and self-affinity, it used the 15-5PH steel that was characterized by metallographic and tensile tests. The metallography allows the microstructural characterization of this steel and proved the presence of the martensite phase in the slats form and a fine-grained, both in the radial and in the axial direction of the dowel. The tensile test (ASTM E8) of this material allowed the determination of the mechanical properties, so based on the obtained results it was possible to affirm that the 15-5PH steel has high mechanical properties and a good stretch. Besides, the specimens also underwent testing of crack propagation, standardized by ASTM E647-00, thus it was obtained the fracture surfaces for characterization under monofractal and multifractal approaches. In front of all the exposed it was possible to conclude that in all measurements the correlation between the crack tip position and the fractal dimension was established in accordance with changes in the thickness and in the fracture micromechanisms presents. Furthermore, the multifractal approach was more sensitive to these variations allowing a more detailed characterization of the morphology

Obtenção e caracterização de compósitos via RTM com alta fração de fibras de carbono processados à temperatura ambiente

After confirming the high specific mechanical properties of composite materials by scientific studies conducted over the last decades, one of the challenges of this new class of materials is the ability to achieve mass production at a more affordable cost, which has become indispensable. The Resin Transfer Molding (RTM) is an excellent method for manufacturing composite materials. Despite being a process widely used by international companies in the production of high performance structural composites, only a short time the national aviation industry has shown interest in implementing this type of processing to more complex structures and greater structural responsibility. In aeronautical projects, the reproducibility and the relative low cost of this process, several studies have been performed in Brazil for learning and perfecting this technique. This process is suitable for producing polymer components both simple as complex geometry, and allows to achieve consistent thickness, with high quality finish and without limiting range. Polymeric composite components for the high mechanical stress applications such as aircraft structures, satellites, etc., require a strict control of volume fractions of the composite constituents, beyond the knowledge of their mechanical and thermal properties. Therefore, in this experimental work degree study on the mechanical, thermal and of porosity composites processed by RTM processed characterization was performed. This characterization was performed targeting a possible aerospace application of this composite material. For the production of composites, process equipment (RTM RTM injector Radius 2100cc) was used. The processed carbono/epoxy composites were characterized via flexure tests mechanically and thermally analysis via DMA, DSC and TGA. To determine the volume fraction of fibers, the composite samples were analyzed via matrix digestion (ASTM D3171) ... (Complete abstract click electronic access below)

Criação de novo procedimento de engenharia que possibilite a rastreabilidade das tubulações de uma indústria química

The number of piping in an industry is high. Through this piping are conducted several kind of products at several temperature and pressure conditions. In a chemical company, the piping quantity conducting harmful chemical products to human health and to the environment is higher. Nowadays the theme sustainability is often mentioned and harm to environment may cause irreversible damage to the human being, to the fauna, to the flora and to company´s credibility. In this context, controlling over the piping to avoid accidents is mandatory. The objective of this monograph is to create a procedure which enables the chemical companies piping traceability. This monograph analyses the several existent traceability system in the three economy sectors and approaches the technical question of industrial piping in order to create a procedure that achieves its objectives as a technical document and at the same time be economically feasible, with low complexibility level and high practicability. Some possibilities to elaborate this procedure had been studied, as the creation of an alphanumeric code and making with a chisel in the pipeline based on ASTM F2897 and the use of chips to store the information. However, the procedure which best meet the requirement as low cost and high applicability is filling out an electronic plan with information about welding process, welding certification, welding consumables and inspections

Análise da influência da concentração de feixeis de fibras de bambu em ensaios de piso

Bamboo has one of the highest growth rates among plants, however, its lignifications (which confers resistance) takes around a few years and, therefore, certain physical characteristics and mechanical, that depend on this process will only be acquired between the three to six years old. In addition, bamboo also has significant density variations in different parts of the stem, both in the radial direction as the axial. In particular the radial direction, where the density found in the inner and outer (near the bark) of a single stem can range on average from 0.5 to 0.9 g/cm3. Thus, the application of bamboo as a floor, there to examine whether both sides of the bamboo (internal and external), provide resistance properties required for that purpose. In this study sought to characterize and quantify the influence of the concentration of fiber bundles in the inner and outer sides of rules or bamboo strips of bamboo flooring through testing service. Analyses performed were based on ASTM D 2394- 83 for wooden floors and derivatives. This was necessary because of the absence of a specific prohibition of the use and testing of floors made of bamboo and its products. The data were analyzed by ball indentation test shooting, test for resistance to abrasion, indentation test for stress / load treadmill test and by indentation loads applied to small areas - test the jump. The results of the tests were extremely friendly bamboo, even this presents considerable differences between the resistances obtained from assay of the cover of the inner and outer face, being comparable with those of many commonly used to manufacture wood flooring. This comparison was made possible by information from technical trials of several floors made with wood

Determinação por meio de planejamento de experimentos da influência do lixamento nas medidas de dureza com durômetro portátil de método UCI

The hardness has an important role in quality control, in research studies and metallurgical and mechanical specification, selection and comparison of various materials. This property is of extreme importance in the oil industry because it is a determining factor to ascertain the safety of the material used in pressure vessels and pipelines. Due to the inability to stop the equipment while checking the hardness, the hardness testers are widely used portable method UCI, its great advantage is the fact that an essay fast, simple realization and not be considered a non-destructive testing with a good relationship money. The objective is to determine if there is significant difference in hardness measurements between 80 and 1200 sandpaper using a portable hardness tester UCI method, the material applied in gas storage spheres composition ASTM 516 Gr 70. After determining the number of homogeneity, we performed the hardness profile to isolate the major factors influencing the hardness part: cold rolling and segregation of impurities. Factors Cooling and sanding were analyzed using the method of design of experiments (DOE), in which it was demonstrated that neither variables nor their interactions, has significant influence on the hardness measurements by portable MIC 10. This fact will lead to reduction in time and cost for surface preparation

Estudo da viabilidade de sedimentos formulados para a aplicação em estudos ecotoxicológicos e químicos: ênfase para os interferentes endócrinos 17alfa-etinilestradiol e 17beta-estradiol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Usinabilidade e integridade superficial de implantes dentários

Pós-graduação em Engenharia Mecânica - FEIS

Ensaios laboratoriais para a determinação da resistência de conexão entre geogrelhas de PVA e blocos segmentais

During the retaining wall project in soil reinforced with geogrids and face milling system for segmental blocks is essential to determine the maximum connection resistance between the block and the geogrid. Thus, the aim of this study was to analyze the connection resistance based on ASTM D- 6638-01 between the segmental block model MW of Muros Terrae® company with the geogrids model Fortrac® M 35 / 20x20, Fortrac® M 55 / 30x20, Fortrac® M 80 / 30x20 and Fortrac® M 110 / 30x20 of HUESKER Synthetic GmbH using gravel 1 as a filling material. As a result, the resistance curves were obtained for the four models of geogrids and was described how it fracture. An additional investigation was the average gain connection resistance percentage when it is applied to geogrid a second layer instead of a single layer. The average percentage gains in the connection resistance to the geogrids model Fortrac® M 35 / 20x20, Fortrac® M 55 / 30x20, Fortrac® M 80 / 30x20 and Fortrac® M 110 / 30x20 were, respectively, 63.20 %, 63, 47%, 62.23 % and 51.34 %. Finally, we made a comparative analysis of the results of this study with those obtained by Guimarães (2006), Urashima et. al (2008) and Almeida and Toma (2011) to evaluate which combinations offered higher connection resistance