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424 results on '"support structure"'

410. Influence of Superelement Support Structure Modeling on the Loads on an Offshore Wind Turbine with a Jacket Support Structure.

Author

Ying Tu and Vorpahl, Fabian

Abstract

The article reports on a study concerning the effects of a superelement modeling approach on the load of an offshore wind turbine with a jacket support structure. Topics discussed include the feature of the superelement approach, a comparison between the mass and eigenfrequencies of the superelement jacket models and a reference shell model and the difference in the load bearing behavior of the two models.

Published
2014

411. Challenges in the Support Structure Design and Assembly of HD3, a $\hbox{Nb}_{3}\hbox{Sn}$ Block-Type Dipole Magnet

Author

J. Lizarazo, Paolo Ferracin, Soren Prestemon, Shlomo Caspi, Helene Felice, A.R. Hafalia, J. M. Joseph, F. Borgnolutti, D.R. Dietderich, Arno Godeke, Daniel W. Cheng, G.L. Sabbi, Maxim Marchevsky, and Xiaorong Wang

Subjects
Physics, General Physics, Condensed matter physics, Aperture, Mechanical engineering, Particle accelerator, Materials Engineering, Superconducting magnet, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, law.invention, Dipole, chemistry.chemical_compound, chemistry, law, Dipole magnet, Electromagnetic coil, Magnet, Nb3Sn, Electrical and Electronic Engineering, Niobium-tin, support structure
Abstract

As part of the development of very high field dipole magnets for particle accelerators, the Superconducting Magnet Program at Lawrence Berkeley National Laboratory is developing block-type dipole magnets. One of the main challenges of this geometry is to provide support to the coil in the aperture while maintaining an adequate clear bore. Through finite element method analysis, strain-gauge measurements, and test results, this paper reviews the design of HD3, a 1-m-long, 43-mm-bore Nb3Sn dipole magnet, presents the findings in terms of strain gauges monitoring, and summarizes their implications. © 2002-2011 IEEE.

Published
2013

412. Development of volume-stable adipose tissue constructs using polycaprolactone-based polyurethane scaffolds and fibrin hydrogels.

Author

Wittmann K, Storck K, Muhr C, Mayer H, Regn S, Staudenmaier R, Wiese H, Maier G, Bauer-Kreisel P, and Blunk T

Subjects
Adipose Tissue cytology, Adult, Female, Humans, Stem Cells cytology, Adipose Tissue metabolism, Fibrin chemistry, Hydrogels chemistry, Polyesters chemistry, Polyurethanes chemistry, Stem Cells metabolism, Tissue Scaffolds chemistry
Abstract

Adipose tissue engineering aims at the restoration of soft tissue defects and the correction of contour deformities. It is therefore crucial to provide functional adipose tissue implants with appropriate volume stability. Here, we investigate two different fibrin formulations, alone or in combination with biodegradable polyurethane (PU) scaffolds as additional support structures, with regard to their suitability to generate volume-stable adipose tissue constructs. Human adipose-derived stem cells (ASCs) were incorporated in a commercially available fibrin sealant as well as a stable fibrin hydrogel previously developed by our group. The composite constructs made from the commercially available fibrin and porous poly(ε-caprolactone)-based polyurethane scaffolds exhibited increased volume stability as compared to fibrin gels alone; however, only constructs using the stable fibrin gels completely maintained their size and weight for 21 days. Adipogenesis of ASCs was not impaired by the additional PU scaffold. After induction with a common hormonal cocktail, for constructs with either fibrin formulation, strong adipogenic differentiation of ASCs was observed after 21 days in vitro. Furthermore, upregulation of adipogenic marker genes was demonstrated at mRNA (PPARγ, C/EBPα, GLUT4 and aP2; qRT-PCR) and protein (leptin; ELISA) levels. Stable fibrin/PU constructs were further evaluated in a pilot in vivo study, resulting in areas of well-vascularized adipose tissue within the implants after only 5 weeks. Copyright © 2013 John Wiley & Sons, Ltd., (Copyright © 2013 John Wiley & Sons, Ltd.)

Published
2016
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414. Jeřáb nástěnný

Author

Malášek, Jiří, Kašpárek, Jaroslav, Malášek, Jiří, and Kašpárek, Jaroslav

Abstract

Tato bakalářská práce se zabývá konstrukčním návrhem nástěnného jeřábu pro nosnost 800 kg a délku vyložení 3 150 mm. Obsahuje důležité pevnostní výpočty včetně kontroly výložníku na únavu a na klopení s ohledem na příslušné normy. Dále obsahuje rozbor výběru vhodného kladkostroje dle současné nabídky výrobců. Součástí práce je také výkresová dokumentace., This bachelor thesis deals with a construction proposal of wall crane for capacity 800 kg and unloading arm 3 150 mm. It contains important strength calculations including checking boom to fatigue and roll with respect to the relevant norms. It also includes analysis of the selection of a suitable hoist according to current offer manufacturers. The work also involves drawings.

415. Jeřáb nástěnný

Author

Malášek, Jiří, Kašpárek, Jaroslav, Malášek, Jiří, and Kašpárek, Jaroslav

Abstract

Tato bakalářská práce se zabývá konstrukčním návrhem nástěnného jeřábu pro nosnost 800 kg a délku vyložení 3 150 mm. Obsahuje důležité pevnostní výpočty včetně kontroly výložníku na únavu a na klopení s ohledem na příslušné normy. Dále obsahuje rozbor výběru vhodného kladkostroje dle současné nabídky výrobců. Součástí práce je také výkresová dokumentace., This bachelor thesis deals with a construction proposal of wall crane for capacity 800 kg and unloading arm 3 150 mm. It contains important strength calculations including checking boom to fatigue and roll with respect to the relevant norms. It also includes analysis of the selection of a suitable hoist according to current offer manufacturers. The work also involves drawings.

416. Jeřáb nástěnný

Author

Malášek, Jiří, Kašpárek, Jaroslav, Malášek, Jiří, and Kašpárek, Jaroslav

Abstract

Tato bakalářská práce se zabývá konstrukčním návrhem nástěnného jeřábu pro nosnost 800 kg a délku vyložení 3 150 mm. Obsahuje důležité pevnostní výpočty včetně kontroly výložníku na únavu a na klopení s ohledem na příslušné normy. Dále obsahuje rozbor výběru vhodného kladkostroje dle současné nabídky výrobců. Součástí práce je také výkresová dokumentace., This bachelor thesis deals with a construction proposal of wall crane for capacity 800 kg and unloading arm 3 150 mm. It contains important strength calculations including checking boom to fatigue and roll with respect to the relevant norms. It also includes analysis of the selection of a suitable hoist according to current offer manufacturers. The work also involves drawings.

417. Jeřáb nástěnný

Author

Malášek, Jiří, Kašpárek, Jaroslav, Matuška, Michal, Malášek, Jiří, Kašpárek, Jaroslav, and Matuška, Michal

Abstract

Tato bakalářská práce se zabývá konstrukčním návrhem nástěnného jeřábu pro nosnost 800 kg a délku vyložení 3 150 mm. Obsahuje důležité pevnostní výpočty včetně kontroly výložníku na únavu a na klopení s ohledem na příslušné normy. Dále obsahuje rozbor výběru vhodného kladkostroje dle současné nabídky výrobců. Součástí práce je také výkresová dokumentace., This bachelor thesis deals with a construction proposal of wall crane for capacity 800 kg and unloading arm 3 150 mm. It contains important strength calculations including checking boom to fatigue and roll with respect to the relevant norms. It also includes analysis of the selection of a suitable hoist according to current offer manufacturers. The work also involves drawings.

418. Porter la cause devant les Hautes Cours

Author

Durand, Corentin, Israël, Liora, Durand, Corentin, and Israël, Liora

Abstract

Quelles transformations connaissent des litiges individuels avant d’aboutir, comme symboles d’une cause, devant des Hautes Cours françaises ? L’analyse de plusieurs affaires dans le champ de la lutte contre les discriminations et la défense des droits des personnes détenues fait apparaître comment des griefs se voient transmués en des questions juridiques originales et « intéressantes » et en vecteur de transformations sociales plus larges. Pour cela, il est nécessaire de s’intéresser aux transformations induites par le déplacement du contentieux tout au long de la chaîne juridictionnelle et à l’intervention de différents types de juristes (avocat·es à la Cour, avocat·es aux Conseils, salarié·es d’association), voire d’autres militant·es. L’étude longitudinale d’affaires montre que les configurations d’acteurs et d’actrices correspondent à des articulations variables entre politisation et technicisation des cas. La stabilité de ces configurations, tout particulièrement s’agissant de la relation entre avocat·es défendant la cause aux différents niveaux, apparaît cruciale. D’une part, elle garantit un certain accord sur la dimension juridique mais aussi la portée politique des problèmes traités. D’autre part, elle inscrit les contentieux individuels dans un horizon temporel plus large, l’intégrant à un jeu itératif et cumulatif où chaque décision – apparemment positive ou négative – peut servir d’appui pour des stratégies futures, lesquelles dépassent dès lors les requérant·es individuel·les., How do individual disputes evolve until they end up, as symbols of a cause, before French high courts ? An analysis of several cases in the field of anti-discrimination law and the defense of prisoners’ rights shows how grievances are transformed into original and “interesting” legal issues, and into vectors of broader social transformations. We consider how movements advance their claims along the jurisdictional chain, and how different types of lawyers intervene all along (court lawyers, supreme court lawyers, association employees), besides other activists. Longitudinal study of cases demonstrates how various configurations of actors correspond to variable articulations between politicization and technicalization of cases. The stability of these configurations, particularly in the relationship between lawyers defending the case at different levels, appears to be crucial. On the one hand, it helps to secure a coherent vision of the problem, from a legal as well as from a political perspective. On the other hand, it places individual litigation in a broader time frame, making it part of an iterative and cumulative game in which each decision – apparently positive or negative – can serve as a basis for future strategies, sometimes far beyond the individual claimants first initiative.

419. Pendulum impact testing of an impact-breakaway, windresistant base connection for multi-post ground signs.

Author

Florida. Dept. of Transportation. Research Management Center, Consolazio, Gary R., Bui, Long H., Walters, Robert A., University of Florida. Dept. of Civil and Coastal Engineering, Florida. Dept. of Transportation. Research Management Center, Consolazio, Gary R., Bui, Long H., Walters, Robert A., and University of Florida. Dept. of Civil and Coastal Engineering

Abstract

BDK75 977-40, Roadside signs play an important role in traffic control systems and must be placed adjacent to roadways. If they are not designed, fabricated, and installed properly, ground signs may pose potential hazards to vehicle passengers in the event of a vehicular collision with a, sign structure. Ground signs must be strong enough to resist hurricane wind loading and self-weight, and yet sufficiently frangible to avoid, extreme vehicular deceleration on impact. Such deceleration can cause abrupt occupant deceleration or excessive vehicle compartment, deformation, either of which can cause serious or fatal occupant injuries. Consequently, sign structures located adjacent to roadways are, generally designed to break away or yield under vehicle impact loading. Presently, a breakaway slip-base connection system is used in, Florida. The breakaway mechanism of this system, however, depends on specific pretension levels in the bolts of the connection., Therefore, the performance of this system is undesirably sensitive to the level of bolt-torque that is imposed during installation and, maintenance., In this study, a new breakaway sign post base connection, the ‘shear-controlled moment collar’, was developed and subjected to, static and dynamic testing. The new connection system is capable of resisting code-specified equivalent static hurricane wind loads, but, also breaks away under low energy impact (vehicular) loads. Development of the connection involved several phases: conceptual, development using nonlinear dynamic finite element analysis; structural design; validation of wind load capacity using static experimental, testing; and validation of breakaway performance using pendulum impact testing. Experimental determination of friction coefficients for, Teflon sheets, used in conjunction with structural steel, was also carried out. In addition, a permanent high-energy impact pendulum test, facility was designed and constructed as part of this research and used to conduct dynamic impact tests on the newly developed breakaway, connection.

420. Pendulum impact testing of an impact-breakaway, windresistant base connection for multi-post ground signs : [summary].

Author

Consolazio, Gary R., University of Florida, Consolazio, Gary R., and University of Florida

Abstract

BDK75 977-40, Roadside signs are critical to traffic control., However, if not properly designed to yield, upon vehicle impact, these signs become lifethreatening, hazards. Yet, the signs must be able, to withstand wind loading, in Florida, up to, hurricane force winds. In a disaster, a collapsed, sign poses two dangers: drivers no longer receive, the sign’s information, and it can obstruct traffic, lanes. Current sign supports, meet these challenges, but, their breakaway mechanism, is undesirably sensitive to the, accuracy of the torque that is, imposed on the bolts during, installation and maintenance.

421. Optimisation of Downskin Parameters to produce Metallic Parts Via Laser Powder Bed Fusion process: an overview

Author

Vittorio Viale, John Stavridis, Alessandro Salmi, Federica Bondioli, and Abdollah Saboori

Subjects
Support structure, Control and Systems Engineering, Additive Manufacturing, Laser Powder Bed Fusion, Downskin parameters, Mechanical Engineering, Industrial and Manufacturing Engineering, Software, Computer Science Applications
Abstract

Additive manufacturing technologies are considered advanced processes in which it is possible to produce complex shape components layer-by-layer. In these technologies, it is reported that in producing parts with angles higher than 45°, no support is required. Depending on the material below this angle, it is necessary to use the support structures to dissipate the heat and counterbalance the force of the recoding blade. During the building process, it is well documented that there is a risk of part detachment at low angles that can result in failure. On the other hand, a heavy dross formation on the downskin surface will occur if no failure happens, resulting in a surface with scarce quality. Hence, many efforts have been undertaken to face this challenge and study the effect of various parameters, such as layer thickness, laser power, and scan speed, on the quality of the downskin surface of the minimum printable angle without the support requirement. This review offers an overview of the last progress on the effect of process parameters on the surface quality of the downward surfaces in the production of complex parts via the laser powder bed fusion process. This review highlights the best practices that may be considered for future works to find effective parameters for producing complex shape components with low angles without support structures.

422. Finish machining of Ti6Al4V SLM components under consideration of thin walls and support structure removal

Author

Sebastian Junghans, Wolfgang Hintze, Robert von Wenserski, and Carsten Möller

Subjects
0209 industrial biotechnology, Materials science, Mechanical engineering, 02 engineering and technology, Industrial and Manufacturing Engineering, SLM, Wirtschaft [330], precision Machining, 020901 industrial engineering & automation, 0203 mechanical engineering, Machining, Artificial Intelligence, Deflection (engineering), ddc:330, titanium, Selective laser melting, Aerospace, Technik [600], support Structure, business.industry, Titanium alloy, Clamping, 020303 mechanical engineering & transports, Powder bed, milling, business, ddc:600, additive manufacturing
Abstract

Using additive manufacturing (AM) technologies such as powder bed based selective laser melting, it is possible to realize new bionic designs for Ti6Al4V aerospace components, thus significantly reducing weight. With these technologies, the goals of reducing emissions in the aviation industry can be achieved while passenger numbers are growing at the same time. In order to fulfill the quality requirements of the components, the AM process chain includes many further process steps in addition to melting, such as heat treatment. Furthermore, the functional surfaces must be machined and the support structures removed. These are essential for selective laser melting. The paper shows how the deflection of the workpiece can be minimized by milling thin-walled functional surfaces using a clamping device with support points. This increases the geometric accuracy considerably. Finally, the paper shows the results for milling support structures. The design of the support structure has a high effect on the machining behavior. Finally, results are presented that show the influence of different milling strategies on the surface quality of AM components, considering the support structures.

423. Investigation of a slip joint connection between the monopile and tower of an offshore wind turbine

Author

Segeren, M. L. A. and Eliz-Mari Lourens

Subjects
slip joint, monopile, alternative transition piece, support structure
Abstract

To circumvent current industry problems related to the settling of grouted connections, a steel-to-steel or slip joint connection is proposed for fitting a transition piece onto an installed monopile foundation. In the first part of this contribution, a simplified dynamic analysis of the installation of such a joint is considered. Assuming velocity dependent Coulomb friction, slip-stick equations of motion are derived for a simplified 1-D model of the joint, and the slip distance under self weight and resulting overlap lengths are calculated for different initial cone angles and friction coefficients. It is concluded that even for small initial cone angles, small angle differences between the top and bottom cone, and low friction coefficients, the tangential displacement caused by the self weight is insufficient to reach the desired contact overlap. In the second part of this contribution, the static capacities (axial and bending) of the joint in the in-place situation are determined by means of a FE model. Contact analyses are performed based on the ideal situation in which the two parts of the joint is initially in full contact. Of the parameters varied in these analyses, small cone angles and large overlaps are identified as most conducive to a succesfull transferral of the loads from the transition piece to the monopile. Given the uncertainty on the friction coefficient, it is then also recommended to use a cone angle of 1? and preferably an overlap > 1.5D.

424. Study of the consolidation process under macro- and microscopic thermal effects in selective laser sintering and selective laser melting

Author

Jhabvala, Jamasp, Glardon, Rémy, and Boillat, Eric

Subjects
frittage sélectif par laser, fluid flow, stratégies de balayage, fusion sélective par laser, Frenkel, écoulement de fluide, poudre métallique, éléments finis, gradients thermiques, thermal model, interparticular neck, capillary, cou interparticulaire, metallic powder, capillaire, modèle thermique, finite elements, scanning strategies, thermal gradients, Selective Laser Melting, consolidation, Selective Laser Sintering, support structure, structure de supports
Abstract

Selective Laser Sintering (SLS) and Selective Laser Melting (SLM) are parent Additive Manufacturing processes using a laser to solidify metallic, ceramic, polymer or composite powders. During the process, the object is built layer by layer. A laser source is responsible for the consolidation, by local heating. The light is deviated by a scanning head according to the instructions of an STL file. Then partial fusion of the particles takes place, followed by a solidification of the liquid created. Kinetics of these steps are very high and play an important role in the final microstructure (rearrangement of the particles, pore creation, residual stresses). In the case of polymers and composites the technique is now well understood and widely used, but for metals and ceramics it suffers from a lack of precision, surface roughness and poor mechanical properties. The goal of this Ph.D. work is to understand the effect of the thermal gradients on the consolidation process, using different laser parameters (power, pulse frequency, scan speed,…). In SLS, microscopic thermal gradients arise, due to the fact that the laser is pulsed and that only the exterior of the powder particles is molten. A thermal model to describe the interaction between a laser beam and a (spherical) grain is proposed. This model allows for the incorporation of the latent heat of fusion and for a realistic surrounding. The absorbed laser intensity is modeled by means of the Mie theory. Experiments where two particles of powder are isolated and illuminated by the laser are carried out in order to measure the interparticular necks and the volume of liquid formed for different repetition rates. The thermal model leads to good predictions of the particles final sintering state. Fluid flow models are investigated in order to determine the dynamic of the molten liquid. The main issue is to explain the capillary flow mechanisms leading from the molten material to the neck formation. Two models are derived to simulate the fluid flow between the particles. The first one simulates a capillary flow between two parallel plates. The second one deals with energetic considerations arising from Frenkel's principle. In both cases, the final output is the liquid life-time necessary to get the interparticular neck lengths experimentally observed. We point out that the two models predict the same liquid lifetime, although they are derived with different hypotheses. In SLM, continuous lasers are used and one has to deal with macroscopic thermal gradients, since the particles are completely molten. A very high laser power is used and the negative thermal effects (like thermal stresses or balling effects) are important. A solution to control them is to adjust the scanning strategy. Four scanning strategies are investigated for material with different thermal conductivities. The three-dimensional model used to describe the laser-matter interactions and the temperature evolution of the scanned powder bed allows for a finite latent heat (Stefan-problem) and for conductivity modifications due to the consolidation. We show that this finite element thermal model can be efficiently used to anticipate most of the problems (like cracks or balling) arising in practice. The benefit of avoiding thermal gradients is shown, in particular by EBSD analysis. Finally, applications of the SLS/SLM technique on different pieces built during this work are shown. A new way to build support structure is also proposed.

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