The paper presents results of a research project founded by the Swiss Federal Nuclear Inspectorate concerning the application of the Master Curve approach in nuclear reactor pressure vessels integrity assessment. The main focus is put on the applicability of pre-cracked 0.4T-SE(B) specimens with short cracks, the verification of transferability of MC reference temperatures T0 from 0.4T thick specimens to larger specimens, ascertaining the influence of the specimen type and the test temperature on T0, investigation of the applicability of specimens with electroerosive notches for the fracture toughness testing, and the quantification of the loading rate and specimen type on T0. The test material is a forged ring of steel 22 NiMoCr 3 7 of the uncommissioned German pressurized water reactor Biblis C. SE(B) specimens with different overall sizes (specimen thickness B=0.4T, 0.8T, 1.6T, 3T, fatigue pre-cracked to a/W=0.5 and 20% side-grooved) have comparable T0. T0 varies within the 1σ scatter band. The testing of C(T) specimens results in higher T0 compared to SE(B) specimens. It can be stated that except for the lowest test temperature allowed by ASTM E1921-09a, the T0 values evaluated with specimens tested at different test temperatures are consistent. The testing in the temperature range of T0 ± 20 K is recommended because it gave the highest accuracy. Specimens with a/W=0.3 and a/W=0.5 crack length ratios yield comparable T0. The T0 of EDM notched specimens lie 41 K up to 54 K below the T0 of fatigue pre-cracked specimens. A significant influence of the loading rate on the MC T0 was observed. The HSK AN 425 test procedure is a suitable method to evaluate dynamic MC tests. The reference temperature T0 is eligible to define a reference temperature RTTo for the ASME-KIC reference curve as recommended in the ASME Code Case N-629. An additional margin has to be defined for the specific type of transient to be considered in the RPV integrity assessment. This margin also takes into account the level of available information of the RPV to be assessed.

M. Tech. (Mechanical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / The purpose of this study was to design a composite overwrapped pressure vessel by combining the best optimal structural options. This study investigated the effects of constituents such as fibre and shell thickness, on the bursting strength. Thereafter, these constituents were combined in order to achieve optimization of strength for an improved sustainable composite pressure vessel. The analytical method was carried out using the Tsai-wu failure theorem. The developed analytical equations were solved with Matlab 2016 software to determine composite fibre and shell thickness. With variation of the vessel’s liner, a total of 56 parts were created on two different profiles with purpose of generating of vessels resistant to bursting failure. Henceforth, the structural integrity of fibre imparted into the design was optimally analyzed at an angle of 55⁰, through the negative and positive directions. The shell thickness overwrapping the liner, being as well an influential factor to this optimization, was, therefore, analyzed on symmetrical and asymmetrical lamination patterns. The optimal fibre and shell thickness range were thereafter determined on a first ply failure and hoop stress threshold approach. Additionally, the identified optimal range of pressure vessel constituents were numerically validated, on Abaqus/CAE software, to have a degree of reassurance on the result generated, using Hashin failure criteria. Optimal design with improved strength and weight factor was therefore achieved by combining the generated optimal vessel constituents yielded from Minitab software version 2016. The generated results of the study revealed no change on the fibre thickness determined with respect to direction. For shell thickness on the other hand, asymmetrical pattern was identified as the desired sequence of lamination. In addition, with two profiles considered in the research, the composite constituents were found for a p value of 0.066, to be optimal on profile 1 at 0.0048 mm of liner, 0.0005 mm of fibre and 0.0027 mm of shell. The profile 2 on the other hand, revealed optimization of liner at 0.0095 mm, fibre at 0.0021 mm and shell at 0.0055 mm. Through combination of these ultimate constituents the response optimizer on Minitab software generated optimal bursting strength with factor of 4% improvement with a weight reduction of 33% compared to the stainless steel vessel. It was, therefore, concluded that profile 1 was the most optimal with hoop strength of 123.43 MPa, Von Mises of 178.56 MPa and Tresca of 179.48 MPa.

The Paris-Edinburgh cell (PEC) is a widely used opposed-anvil device for neutron scattering. Since its development, it has been used to study a number of samples loaded as solids or liquids. However, studying gases at room temperature has not yet been possible. Up until now only a few gases could be loaded as liquids, in cryogenic conditions. Thus, it was impossible to study many gases and gas mixtures and also it was difficult to use gases as pressure-transmitting media (PTM). In order to overcome these limitations, a technique that would enable loading of gases into the PEC was required. The work described in this thesis was focused on the design and use of a gas-loading system for the PEC. The challenge of designing such a system comes from the fact that the gases need to be loaded into the gasket at sufficient density in order to achieve any significant pressure during further compression in the cell. This can be achieved by using a separate pressure vessel. Because the whole PEC is too large to be placed inside the vessel, a technique of loading gas into the anvils separated from the rest of the cell had to be devised. Designing the holder for the anvils, which would make this possible, presented a major challenge as it should allow the anvils to be transferred between the vessel and the PEC, with the gasket filled with high-pressure gas. Then it needs to allow further compression of the gasket inside the PEC. The developed system consists of a pressure vessel and a locking clamp for the anvils. The pressure vessel is a closed-end thick-walled cylinder with a top cover which has an opening for a piston. The vessel is placed on the table of a hydraulic press and the piston, sealed by a high-pressure reciprocating seal, is used to transmit the force from hydraulic ram onto the anvils which are held by the clamp and placed inside the vessel. One of the anvils is fixed to the clamp and the other one is supported by spring-loaded latches - the latches engage when the anvils are pushed towards each other. Thus, when the force is applied onto the anvils to compress the gasket, latches lock the anvils in their positions stopping them from retracting and maintaining the gasket compressed after the force is released. The clamp allows the gasket to be filled with the gas and then deformed to seal the compressed gas. The locking mechanism keeps the gasket compressed, which enables the clamp to be transferred from the vessel to the PEC. After the system was built and tested, it was installed at ISIS neutron source (Oxfordshire, UK), where it has been used in several experiments. The first experiment prepared with the gas-loading system was a neutron diffraction study of nitrogen at high pressure. Nitrogen was chosen as a sample material because its high-pressure structural phase diagram is well established. Nitrogen was loaded into the gasket using the gas loader and then it was compressed in increments to 6 GPa in the PEC. β and δ phases of solid nitrogen were clearly seen in the collected neutron diffraction data. The experiment proved the usability of the gas-loading system and verified its expected performance. The second experiment utilizing the gas-loading system was to study singlecrystal and powder samples of sodium chloride (NaCl) and squaric acid (H2C4O4). For these studies argon was used as a PTM, replacing the conventionally used methanol-ethanol mixture (ME). Up until this experiment the highest pressure reported in single-crystal neutron-scattering experiments was 12 GPa. This limit was set by the solidi cation pressure of ME. With argon as the PTM, the samples were compressed to 15 GPa without any damage to the crystals. Another advantage of replacing ME with argon is improved hydrostaticity. The highest pressure that ME remain hydrostatic to is 11 GPa. Compressing beyond this point causes sheer stress acting on the sample which affects the quality of the neutron scattering data manifested in the appearance of peak-broadening in the diffraction patterns. With use of argon, the powder samples have been compressed to 18 GPa while maintaining quasi-hydrostatic pressure conditions, resulting in clean and sharp diffraction patterns without any noticeable peak-broadening.

O planeta Terra tem aproximadamente três quartos submersos em água, ainda assim, estima-se que somente são conhecidos 5% dos mares e oceanos. Nas últimas décadas, os AUVs (Autonomous Underwater Vehicles) se converteram em uma ferramenta útil para a exploração dos oceanos por levar a bordo vários equipamentos com um relativo baixo custo de operação. A parte estrutural dos AUVs, usualmente cascas cilíndricas, tem sido estudada. De modo geral, os objetivos desses estudos visam a manter a rigidez e deixar a estrutura mais leve, sob o critério de resistência a flambagem. A falha por flambagem, normalmente, ocorre antes da falha por resistência do material em cascas devido à sua geometria e à influência de imperfeições iniciais. Uma forma de aumentar a rigidez das cascas é o uso de enrijecedores, os quais geralmente são soldados à casca. No entanto, o uso desses enrijecedores em um veículo de pequeno porte diminui o espaço utilizados por diferentes dispositivos e instrumentos do veículo, além de resultar em possíveis inconvenientes na fabricação, tais como aumento do custo e produção de tensões residuais relativas aos processos de soldagem. Portanto, alternativas ao enrijecedor convencional devem ser buscadas para esse tipo de veículo. É possível substituir os enrijecedores convencionais por uma estrutura interna ao vaso de pressão e comum em submersíveis, a prateleira de acomodação da eletrônica. Essa estrutura, chamada aqui de enrijecedores deslizantes, possui cavernas circunferenciais que podem fornecer rigidez à casca e evitar os inconvenientes de redução de volume e de fabricação que os enrijecedores convencionais trazem. No entanto, tal substituição para o aumento de rigidez ainda não foi analisada. Portanto, neste trabalho se propõe analisar o comportamento do enrijecedor deslizante quando utilizado em substituição ao enrijecedor convencional, considerando que ambos fornecem resistência à compressão embora não apresentem as mesmas restrições de graus de liberdade. A análise é feita através de métodos analíticos e numéricos, tipicamente utilizados no estudo de enrijecedores convencionais. / The planet Earth has about three quarters of water, yet it is estimated that only 5% of the seas and oceans are known. In the last decades, the AUVs have become useful tools for the exploration of the oceans by carrying on board several equipment with a relative low cost of operation. The structural part of the AUV\'s, usually cylindrical shells, has been studied as well. In general, the objectives of these studies are to maintain rigidity and to leave the structure lighter, under the criterion of buckling resistance. The buckling failure occurs prior to failure by yielding due to its geometry and the influence of initial shell imperfections. One way to increase the stiffness of the shells is to use stiffeners, which are usually welded to the shell. However, the use of these stiffeners in a small vehicle reduces the space used for different devices and instruments of the vehicle, in addition there are manufacturing drawbacks as residual stresses related to the welding processes. Therefore, alternatives to the conventional stiffener should be sought for this type of vehicle. It is possible to replace conventional stiffeners by an internal structure to the pressure vessel and common in submersibles, the shelf of accommodation of the electronics. This structure, referred to here as sliding stiffeners, has circumferential frame bulkheads that can provide stiffness to the shell and avoid the drawbacks of volume reduction and fabrication that conventional stiffeners bring. However, such substitution for increased rigidity has not yet been analyzed. Therefore, in this work it is proposed to analyze the behavior of the sliding stiffeners when used in substitution of the conventional stiffeners, considering that both provide compressive strength although they do not present the same restrictions of degrees of freedom. The analysis is done by analytical and numerical methods, typical of conventional stiffeners.

Submerged arc welding (SAW) is often the method of choice in pressure vessel fabrication. This process features high production rates, welding energy and/or welding speed and requires minimal operator skill. The selection of appropriate parameters in SAW is essential, not only to optimize the welding process in order to maintain the highest level of productivity, but also to obtain the most desirable mechanical properties of the weld.<p> The focus of this study was to investigate the effect of welding speed on the properties of SA516 Grade 70. Plates of SA516 Gr. 70 steel 17 mm x 915 mm x 122 mm were submerged arc welded with a welding current of 700 A and welding speeds of 15.3, 12.3 and 9.3 mm/s. Following the welding; strength, microstructure, hardness and impact toughness of the specimens were examined. Charpy impact testing was performed according to ASTM E 23 on specimens notched in the weld metal (WM) and in the heat-affected zone (HAZ), to measure the impact toughness. Fractography was performed on broken specimens using optical and scanning electron microscopy in order to correlate the mechanisms of fracture with the impact toughness values.<p> The highest hardness values were in the coarse-grained HAZ followed by the WM with the lowest hardness in the parent metal (PM). The HAZ had higher impact toughness than the WM and PM for all welding speeds. The slowest welding speed (9.3 mm/s) obtained complete penetration and therefore produced the most visually sound weld. The fastest welding speed (15.3 mm/s) had the narrowest HAZ and showed good ductile-to-brittle transition behaviour for both the WM and HAZ specimens, but produced incomplete penetration defects. Welding speed had little affect on the notch toughness of the HAZ with only a 9 J rise in upper shelf energy and an 8 °C drop in the impact transition temperature (ITT) with increased welding speed from 9.3 to 15.3 mm/s. However, for the WM, there was a 63 J drop in the upper shelf energy but also a 41 °C improvement of the ITT between the 9.3 and 15.3 mm/s welding speeds.

Submerged arc welding (SAW) is commonly used for fabricating large diameter linepipes, pressure vessels and wind turbine towers due to its high deposition rate, high quality welds, ease of automation and low operator skill requirement. In order to achieve high melting efficiency required for high productivity, best weld quality and good mechanical properties in manufacturing industries, the welding process parameters need to be optimized. In this study, the effect of SAW current and speed on the physical and mechanical properties of ASME SA516 Gr. 70 (pressure vessel steel) and ASTM A709 Gr. 50 (wind turbine tower steel) were investigated. Three welding currents (700 A, 800 A and 850 A) and four travel speeds (5.9, 9.3, 12.3 and 15.3 mm/s) were used to weld sample plates measuring 915 mm x 122 mm x 17 mm. The weld quality and properties were evaluated using weld geometry measurements, visual inspection, ultrasonic inspection, hardness measurements, optical microscopy, tensile testing, Charpy impact testing and scanning electron microscopy. It was found that the physical and mechanical properties of the weldments were affected by SAW parameters. Severe undercuts were found at high travel speed and welding current. Low heat input caused lack of penetration defects to form in the weldments. The welding process melting efficiency (WPME) achieved was up to 80%. The hardness of the coarse grain heat affected zone (CGHAZ) and the weld metal increased with travel speed. The toughness of both materials increased with increasing travel speed and welding current. The yield and tensile strengths of the weldments of SA516 Gr.70 and A709 Gr.50 steels were within the same range as those of their respective parent metals because all test specimens broke in the parent metals. Also, the parent metals of both steels had the highest fracture strain and percent elongation. The percentage elongation increased with travel speed but decreased with welding current.

Submerged arc welding (SAW) is commonly used for fabricating large diameter linepipes, pressure vessels and wind turbine towers due to its high deposition rate, high quality welds, ease of automation and low operator skill requirement. In order to achieve high melting efficiency required for high productivity, best weld quality and good mechanical properties in manufacturing industries, the welding process parameters need to be optimized. In this study, the effect of SAW current and speed on the physical and mechanical properties of ASME SA516 Gr. 70 (pressure vessel steel) and ASTM A709 Gr. 50 (wind turbine tower steel) were investigated. Three welding currents (700 A, 800 A and 850 A) and four travel speeds (5.9, 9.3, 12.3 and 15.3 mm/s) were used to weld sample plates measuring 915 mm x 122 mm x 17 mm. The weld quality and properties were evaluated using weld geometry measurements, visual inspection, ultrasonic inspection, hardness measurements, optical microscopy, tensile testing, Charpy impact testing and scanning electron microscopy. It was found that the physical and mechanical properties of the weldments were affected by SAW parameters. Severe undercuts were found at high travel speed and welding current. Low heat input caused lack of penetration defects to form in the weldments. The welding process melting efficiency (WPME) achieved was up to 80%. The hardness of the coarse grain heat affected zone (CGHAZ) and the weld metal increased with travel speed. The toughness of both materials increased with increasing travel speed and welding current. The yield and tensile strengths of the weldments of SA516 Gr.70 and A709 Gr.50 steels were within the same range as those of their respective parent metals because all test specimens broke in the parent metals. Also, the parent metals of both steels had the highest fracture strain and percent elongation. The percentage elongation increased with travel speed but decreased with welding current.

Submerged arc welding (SAW) is often the method of choice in pressure vessel fabrication. This process features high production rates, welding energy and/or welding speed and requires minimal operator skill. The selection of appropriate parameters in SAW is essential, not only to optimize the welding process in order to maintain the highest level of productivity, but also to obtain the most desirable mechanical properties of the weld.<p> The focus of this study was to investigate the effect of welding speed on the properties of SA516 Grade 70. Plates of SA516 Gr. 70 steel 17 mm x 915 mm x 122 mm were submerged arc welded with a welding current of 700 A and welding speeds of 15.3, 12.3 and 9.3 mm/s. Following the welding; strength, microstructure, hardness and impact toughness of the specimens were examined. Charpy impact testing was performed according to ASTM E 23 on specimens notched in the weld metal (WM) and in the heat-affected zone (HAZ), to measure the impact toughness. Fractography was performed on broken specimens using optical and scanning electron microscopy in order to correlate the mechanisms of fracture with the impact toughness values.<p> The highest hardness values were in the coarse-grained HAZ followed by the WM with the lowest hardness in the parent metal (PM). The HAZ had higher impact toughness than the WM and PM for all welding speeds. The slowest welding speed (9.3 mm/s) obtained complete penetration and therefore produced the most visually sound weld. The fastest welding speed (15.3 mm/s) had the narrowest HAZ and showed good ductile-to-brittle transition behaviour for both the WM and HAZ specimens, but produced incomplete penetration defects. Welding speed had little affect on the notch toughness of the HAZ with only a 9 J rise in upper shelf energy and an 8 °C drop in the impact transition temperature (ITT) with increased welding speed from 9.3 to 15.3 mm/s. However, for the WM, there was a 63 J drop in the upper shelf energy but also a 41 °C improvement of the ITT between the 9.3 and 15.3 mm/s welding speeds.

Die Geometrie eines Druckbehälters wird unter Zuhilfenahme parametrischer Bezierkurven und durch die Integration einer externen Mathcad-Analyse in Creo hinsichtlich einer harmonischen, meridianen Spannungsverteilung optimiert.

Simulation-News in Creo 1.0 & Creo 2.0 - Mechanica (neu: Simulate) Druckbehälter: Schraubenvorspannung / Betriebslast - Live-Präsentation in Creo 2.0 Berechnung eine Druckbehälters unter Berücksichtigung von: Schraubenvorspannung, Betriebslast, zeitabhängiger Lastaufbringung