Armando H Shinohara

Federal University of Pernambuco | UFPE · Department of Mechanical Engineering

Abstract This work established the fracture probability equation for JIS SM490A steel using the computational model supported by the local approach and the standard Crack Tip Opening Displacement (CTOD) fracture toughness experiments. As the experiments were conducted at a low temperature providing conditions for the brittle fracture, the specimen...

Dynamic frack propagation experiment using rubber tubes has been developed which is intended to simulate running ductile fracture in high-pressure gas pipelines. Crack velocity was measured by high-speed camera. It ranged 100 to 500m/s, depending on pressure. The crack velocity decreased more rapidly in helium gas test than in the air test. This re...

Este trabalho mostra resultados para o imageamento de Raio X de 7.5 Mev Betatron com potência máxima e distância de 1m da fonte ao objeto e a aplicação de técnicas de processamento de imagens para obter o realce e visualização interna de bordas. Como exemplo, foi radiografada a fonte de raios-X que contém chumbo dentro do tubo. Obteve-se a definiçã...

Radiografia industrial para a inspeção da integridade estrutural de dispositivos. Ensaio não destrutivo

Abstract. The friction stir welding (FSW) process for joining the aluminum alloys is a relatively new and is considered a more interesting method than the traditional arc welding process because the residual stress is substantially low and there is practically no distortion of the welded joint. However, even though from both surfaces of the joint i...

The anodizing of aluminum is a common technique used to produce decorative and protective high quality film. This process results in significant volume of industrial sludge containing considerable amounts of colloidal aluminum hydroxide, which is a problem in the disposal of these industrial wastes due to the environmental impact. This paper aims a...

Resumo Este artigo busca analisar indicadores chave de desempenho que possam ser utilizados na gestão da produtividade de estaleiros de construção naval e offshore.

In this work, we have s produced Al2O3-TiO2 ceramic composites reinforced with rare earth oxide, lantânia (La2O3) ranging from 0 to 2 wt%, for the study of their phase stability, structureand microstructural chacteristics. The ceramic composites were produced by thermo-mechanical process. It was observed from the results of XRD after sintering no n...

This report is about a numerical calculation method for the wave energy absorption of a floating 2D cylinder. The least condition for the complete energy absorption by making use of an oscillating cylinder in waves is that the floating cylinder has to be wave-free on one side direction when it is forced to oscillate in a given motion mode. The radi...

An extensive in loco survey of main quartz producing regions in Brazil integrated with physicochemical characterization studies of quartz lascas and their fusion into silica glass bring the possibility of obtaining high quality quartz powder supplies for various industrial applications. The advantage is the relatively simple, cheap and environmenta...

Composite insulators aged in-service for almost 10 years at the transmission line of 230 kV, in an area where brittle fracture of a composite insulator occurred, were inspected by the micro-computed tomography, µ-CT, and by the scanning electron microscope, SEM. As a result, several cracks with different depths under pollutant scale and confined in...

Significant changes in small-angle X-ray scattering intensity can be induced when the energy of incidental Xrays is tuned close to the vicinity of an absorption edge of an appropriate atom contained in the sample. This method enables us to offer new information with respect to the inhomogeneities in materials, for instance, the nature of GP zones i...

The structure of mesophase carbon powders prepared by heating coal-tar pitch at different temperatures was studied using the small-angle X-ray scattering method. The wide-angle diffraction profiles of mesophase carbon powders indicate only the first peak at q = 18 nm-1 and subsequent broad oscillations. A single graphite layer is suggested to be on...

The average particle size of two monodispersed colloidal silica HS-40 and SM-30 and one polydispersed colloidal ferrite has been estimated from the small angle X-ray scattering (SAXS) data using four methods proposed by Guinier, Fankuchen, Hosemann and Porod. The same information was also obtained by the transmission electron microscope (TEM) and c...

The EXAFS technique has been applied for obtaining information on the local atomic arrangements in the near neighbor region of liquid gallium. The EXAFS data of liquid gallium at temperatures of 323 and 473 K can be well explained by considering four immediate neighbors and another four slightly more distant neighbors located so as to form a local...

Texto dedicado aos combustiveis alternativos, 150 paginas.

Energia Solar e Aplicações, 250p.

Nowadays, glass and porcelain insulators are being systematically changed by polymeric insulators, because of its advantages, as easy installation, reduced weight, low cost in the construction and transportation, and resistance to the vandalism. However polymeric insulators have disadvantages, as the difficulty about visual damage detection. Power...

This paper discusses the structural features required to stimulate a strong thermoluminescence (TL) glow peak near 300°C in clear natural quartz. For that reason, fresh TL data taken from several specimens prepared from five single crystals with known impurity content are shown. The TL emission was measured with a test dose of 10mGy of γ-rays in th...

A round robin program was conducted to assess the ability of three different X-radiographic systems for imaging internal fatigue cracks in riveted lap joints of composite glass reinforced fiber/metal laminate. From an engineering perspective, conventional film radiography and direct radiography have produced the best results, identifying and charac...

This work presents results of a comparative study conducted on breakdown voltage measurements in a glass insulators string containing several units with broken glass part. String with 16 insulator units were tested simulating a transmission line of 230 kV. Two arrangements have been adopted: (i) seven good insulators and nine broken units and, (ii)...

Riveted lap joints made of two sheets of Glare ™ are known to develop cracks at the faying surfaces of aluminum sheets when subjected to cyclic axial constant amplitude loading (CAL). The purpose of this work was to conduct high-resolution digital radiographic inspections of cracks generated by the CAL in the aeronautical grade Glare ™ riveted hybr...

In the present work, the microstructure and mechanical properties of structural mortar from glass insulators were studied by X-ray fluorescence, X-ray diffraction, infrared spectroscopy, microhardness and compression testings. The investigated glass insulators were manufactured between the 1960 and 1990 years and had been used in 230 kV transmissio...

The small-angle X-ray scattering (SAXS) in as-grown and heat-treated quartz crystals was investigated as a function of the azimuth angle around the primary beam. For this, samples parallel to (100) were extracted from Z- and −X-growth sectors of a synthetic quartz bar which had the OH content evaluated by infrared spectroscopy (IRS). In addition, S...

In this work, the experimental results of high-voltage in industrial frequency and switching impulse tests conducted to evaluate the influence of polycarbonate protectors (polyprotect) on the values of electrical breakdown voltage of a glass insulators chain with 16 units partially damaged, containing 9 broken insulators, are presented simulating a...

This study investigates the distribution of Al and OH defects in synthetic quartz grown from cylindrical seeds parallel to X, Y and Z crystallographic axes. Prismatic habit crystals were grown with m-, R-, r- and x- faces. The growth sectors were identified by radiation-induced coloration and their morphologies were characterized by X-ray topograph...

In the present study, the morphology and the impurity distribution were investigated in growth sectors formed around the [0001] axis of synthetic quartz crystals. Plates containing cylindrical holes and cylindrical bars parallel to [0001] were prepared by ultrasonic machining and further used as seed-crystals. The hydrothermal growth of synthetic q...

Precision abrasive processes are commonly employed to machine glasses, single crystals and ceramic materials for various industrial applications. Until now, precision machining of hard and brittle solids are poorly investigated in Brazil from the fundamental and applied point of views. Taking into account the major technological importance of this...

Small-angle X-ray scattering was employed to investigate heterogeneities in growth sectors of a large Z-bar synthetic quartz. The measurements were performed in as-grown and heat-treated samples. As a result, X-ray scattering was observed in all samples. The Guinier approximation revealed a polydispersive distribution of heterogeneities in as-grown...

High resolution X-ray Laue topography was conducted on the SPring-8 BL-28B2 beamline, operating at a 5–100 keV energy range. The use of this beamline was particularly suitable for characterization of thick samples of giant blocks of natural quartz used as seeds for growing synthetic quartz; and also to understand the propagation mechanism of disloc...

Small-angle X-ray scattering (hereafter referred to as SAXS) has been widely used for studying structural features of materials in various fields such as physics, chemistry, metallurgy, and biology, because SAXS data enable us to obtain important microstructural parameters such as particle volume and shape of so-called structural inhomogeneities wi...

In the present work, we investigate the wear mechanisms associated with the material removal of quartz in different ultrasonic machining conditions. By using a stationary machine, ultrasonic machining was carried out in X-, Y-, Z-and AT-cut plates of natural quartz and Z-cut plates of synthetic quartz. Cutting tools with square and cylindrical cros...

The potential of ultrasonic machining is investigated as a tool to produce seed crystals for hydrothermal growth of synthetic quartz with required surface finish and unconventional geometries. For this purpose, cylindrical seeds with 5, 10 and 18 mm diameter were obtained along the optic axis of a Z-bar using a conventional ultrasonic machining pro...

A method to grow low dislocation density synthetic quartz by using a special cutting seed geometry is reported. With this method, a relatively high dislocation density seed material is allowable. For such a purpose, a seed of new geometry was prepared and grown in a standard hydrothermal growth condition, long in Y-direction with multiple V-shaped...

This work presents some preliminary results relating training treatment, training temperature and the formation of α′ martensite to the shape recovery effect of stainless shape memory alloys. For the composition tested, the sample shows some mechanical memory (constant tensile stress at 4% strain and constant yield stress throughout the training cy...

In the present study, the feasibility to grow a dislocation-free synthetic quartz with large Z-region from a seed containing high density of dislocation is reported. For such purpose, a seed with new geometric design was prepared. A seed long in Y-direction and containing V-shaped cuts with cutting angle of 90° made on Z-face {0001} was prepared an...

High-purity silica glass prepared from high-purity amorphous and crystalline powders by flame fusion and sintering at high temperatures in vacuum, was heat-treated at 1250°C for several periods of time and its structure was studied using the small-angle X-ray scattering technique. As a result, the structure of silica glass was dependent on its ther...

Etching of various vitreous silica samples over a long period (˜ 200 min) with hydrofluoric acid revealed a high contrast configuration of micron to sub-millimeter order boundaries similar to the grain boundaries of crystalline materials. In order to better understand this new result, various parameters, such as the vitreous silica preparation proc...

A homoepitaxic single-crystal diamond (111) film grown by microwave-assisted chemical vapour deposition (CVD) and fractured along the [110] directions to form small triangles was investigated by X-ray double-crystal topography. The X-ray topographic image showed that all parts of the cleaved CVD diamond film sections uniformly reflected X-rays at t...

X-ray double crystal diffraction topography of homoepitaxial diamond film grown by microwave plasma chemical vapor deposition has been conducted to-study the residual stress generated by the lattice mismatch and defects at the film-substrate interface. Even though the stress-relaxation mechanism occurs by uniform film cracking, and there is no bend...

High-quality as-fused silica glass, heat treated at 1523 K and prepared by the flame-fusion process using natural crystalline quartz and high-purity amorphous silica glass powders, was investigated by small-angle X-ray scattering (SAXS). The X-ray scattering intensity amplitude from the amorphous structure after heat treatment was analysed in terms...

Synthetic quartz crystals were grown on S- and ξ-bar seeds and characterized by X-ray topography. For comparison, synthetic quartz crystals grown on intermediary cutting between S- and ξ-planes (φ=24-42°) seeds were also investigated. As a result, several new growth regions usually not present in the Y-cut of Y- and Z-bars synthetic quartz crystals...

A method to position the seed and Z-region of growth out of the circulating micro-particle flux in commercial autoclave has been used to grow optical grade synthetic quartz. The number of solid inclusions is in the range of 0.02-0.03 particles/cm³, depending on the bar. The observation of X-ray topographic contrast of (0003) reflection s...

The local structure around gallium of 0.5, 1 and 5 at.% in Liquid silicon at 1440 degrees C has been investigated by the extended X-ray absorption fine structure (EXAFS). The amplitude of EXAFS oscillations is distinct for the very dilute case of 0.5 at.% gallium. The EXAFS analysis shows that the structural parameters of Ga-Si pairs change from 2....

The structure of Zr60Al15Ni25, Zr33Y27Al15Ni25 and Y60Al15Ni25 amorphous alloys were studied from the environmental structures of Zr, Y and Ni determined by anomalous X-ray scattering coupled with the least-squares variational technique.

An anomalous small angle X-ray scattering (anomalous SAXS) method has been applied to obtain a possible origin of structural inhomogeneity in amorphous Zr33Y27Al15Ni25 alloy annealed at 773 K for 300 s. The remarkable decrease in intensity is detected for Ni and Zr whereas an increase is clearly observed for Y, when the incident energy approaches t...

The atomic structure of the as-quenched Zr33Y27Al15Ni25 amorphous alloy which has double glass transition temperature was investigated by X-ray diffraction and compared with that of a sample heated at 773 K just above the second glass transition temperature Tg2 (772 K). The environmental structures around Zr, Y and Ni in both samples were determine...

The effects of moisture on grinding of natural calcite using a tumbling ball mill were investigated by X-ray diffraction (XRD), chemical analysis, scanning electron microscopy (SEM) observation and by measuring the specific surface area. The specific surface areas of calcite ground in dry conditions appear significantly smaller than those of calcit...

A novel method has been developed for measuring direct compressive properties such as strength and elasticity of a series of mesophase-pitch-based and PAN-based carbon fibres about 10 m in diameter by uniaxial and transverse compression tests using a micromechanical tester. The fibres were shaped into cylindrical specimens, with their size ratio of...

The effects of Al and H impurities on the crystal morphology of Y-bar synthetic quartz were studied. The growth velocities perpendicular to the Y-axis were evaluated in relation to the Al and H impurity segregations on the growth interfaces. It was found that the -X-growth region has the highest H content and shows the lowest growth velocity, due t...

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Phone: +55 81 21268230, Fax: +55 81 21268232; e-mail: sandrorett@bol.com.br, Phone: +55 16 33739591, Fax: +55 16 3373 9590; e-mail: jrpan@sc.usp.br 3 Federal Institute for Materials Research and Testing (BAM); Berlin; Germany e-mail: Uwe.Zscherpel@bam.de, Juergen.Goebbels@bam.de Abstract Riveted lap joints made of two sheets of Glare ™ are known to...

Palavras-chaves: pré-moldados de gesso, tratamento térmico, ensaios de compressão, densidade.