2,001,175 research outputs found
Fatigue Design For Non-Welded Regions According To New European And American Pressure Vessel Standards
No full textDie EN 13445-3 [1], welche in ihrer ersten Version im Jahr 2002 publiziert wurde, beinhaltet getrennte Ermüdungsnachweise für ungeschweißte und geschweißte Bereichte. Auch die neue, im Jahr 2007 erschienene "ASME Boiler & Pressure Vessel Code Section VIII Division 2" beinhaltet getrennte Nachweise für ungeschweißte und geschweißte Bereiche. Wegen der unterschiedlichen Herangehensweise sind die Methoden der beiden Regelwerke nicht direkt vergleichbar. Aus diesem Grund wurden vergleichbare Auslegungskurven für spezielle Fälle und für Extremwerte der Parameter evaluiert. Unterschiede in der Vorgangsweise werden diskutiert und Beispiele für die speziellen Fälle werden angegeben.
Für die ungeschweißten Bereiche, welche in diesem Beitrag behandelt werden, wurde die folgende Vorgangsweise gewählt: Auslegungskurven aus der EN 13445-3 wurden mit den Extremwerten der notwendigen Korrekturfaktoren korrigiert. Diese korrigierten Auslegungskurven aus der EN 13445-3 wurden verglichen mit den Auslegungskurven aus ASME VIII-2. Als typische Beispiele wurden einige experimentelle Ergebnisse mit den spezifischen Auslegungskurven verglichen.EN 13445-3, which was first published in the year 2002, includes separate fatigue design checks for unwelded and welded regions. Furthermore, the new 2007 ASME Boiler & Pressure Vessel Code Section VIII Division 2 includes separated design checks for welded and unwelded regions. Because of differences in the procedures, the approaches of these standards are not directly comparable.
Therefore, comparable design curves for special cases and/or for extreme values of parameters are evaluated. Differences in the procedures are discussed and examples are given for special cases. For the unwelded regions, which are covered by this paper, the following approach was chosen: Design curves from EN 13445-3 are corrected by the extreme values of the necessary correction factors. These corrected EN 13445-3 fatigue design curves are compared to the design curves given in ASME VIII-2. As examples of typical usage, some experimental results are compared to the specific design curves
ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems
No full textInternational audienc
Retracted: “Residential Energy Efficiency Improvement Using Solar Heating of Water and Air: A Computational Study” [ASME 2017 International Mechanical Engineering Congress and Exposition, Volume 6: Energy, Tampa, Florida, USA, November 3–9, 2017, Conference Sponsors: ASME, ISBN: 978-0-7918-5841-7, Copyright © 2017 by ASME. Paper No. IMECE2017-70041, pp. V006T08A037; 7 pages; doi: 10.1115/IMECE2017-70041]
No full textAbstract
The above referenced paper has been removed from publication. (March 10, 2020)
Copyright © 2020 by ASME</jats:p
Retracted: “Designing a Road-Side Wind Turbine Driven by Winds From the Moving Vehicles” [ASME 2017 International Mechanical Engineering Congress and Exposition, Volume 14: Emerging Technologies; Materials: Genetics to Structures; Safety Engineering and Risk Analysis, Tampa, Florida, USA, November 3–9, 2017, Conference Sponsors: ASME, ISBN: 978-0-7918-5849-3, Copyright © 2017 by ASME. Paper No. IMECE2017-70043, V014T07A001; 8 pages; doi: 10.1115/IMECE2017-70043]
No full textAbstract
The above referenced paper has been removed from publication. (March 10, 2020)
Copyright © 2020 by ASME</jats:p
A technological solution for everywhere energy supply with sun, hydrogen and fuel cells
No full textThe hydrogen economy is still at the beginning but the society, innovation, and market push inexorably towards hydrogen, inspiring the idea to build an energy integrated system that can satisfy, in an independent way, the energy needs of small size consumers. The technologies used for the system design are already available in the market and, at least for the standard solutions, sufficiently mature. The innovation consists of an integration, optimization and industrialization of this modular system, which is an electric zero emissions generator, giving as output power 3,5 kW P. This is the only system able to produce its own fuel, guaranteeing renewable and clean energy, available where and when you want. This system is constituted of a polymer membrane electrolyser, a metal hydride tank, that absorbs and desorbs hydrogen, and a polymer fuel cell. The system modularity can satisfy also greater energy requirements and the hydrogen storage by metal hydride at low pressure guarantees the system safety. Copyright © 2005 by ASME
Optical and Electronic Simulation of Silicon / Germanium Tandem Four Terminal Solar Cells
No full textA tandem solar cell architecture of silicon and germanium solar cells in a mechanical (stack like) arrangement is evaluated to increase the efficiency of light absorption in the far infra-red region from 1107 nm to 1907 nm wavelength which constitutes about 14.5% of the power intensity in the solar AM 1.5 spectrum. In this work the technical feasibility of tandem solar cells is investigated. Here we report on detailed electrical and optical simulations of this structure quantifying the various theoretical and practical loss mechanisms in the encapsulation, interfaces and in the device and indicate that a relative efficiency improvement of 20% may be attainable with silicon and germanium solar cells in this configuration. The optical and electrical parameters for silicon and germanium simulation models were extracted from experimental devices and material vendors. The developed simulation models were validated by comparing the performance of standalone silicon and germanium solar cells with experimental devices reported in the literature.This article, by Vishnuvardhanan Vijayakuman and Dunbar P. Birnie, III, was originally published in Journal of Solar Energy Engineering, copyright 2014 by ASME. It may be used for non-commercial purposes only.Peer reviewe
Direct Numerical Simulation of Rotating Cavity Flows Using a Spectral Element-Fourier Method
No full textA high-order numerical method is employed to investigate flow in a rotor/stator cavity without heat transfer and buoyant flow in a rotor/rotor cavity. The numerical tool used employs a spectral element discretisation in two dimensions and a Fourier expansion in the remaining direction, which is periodic and corresponds to the azimuthal coordinate in cylindrical coordinates. The spectral element approximation uses a Galerkin method to discretise the governing equations, similarly to a finite element method, but employs high-order polynomials within each element to obtain spectral accuracy. A second-order, semi-implicit, stiffly stable algorithm is used for the time discretisation, and no subgrid modelling is included in the governing equations. Numerical results obtained for the rotor/stator cavity compare favourably with experimental results for Reynolds numbers up to Re1 = 106 in terms of velocities and Reynolds stresses. For the buoyancy-driven flow, the energy equation is coupled to the momentum equations via the Boussinesq approximation, which has been implemented in the code considering two different formulations. Numerical predictions of the Nusselt number obtained using the traditional Boussinesq approximation are considerably higher than available experimental data. Much better agreement is obtained when the extended Boussinesq approximation is em-ployed. It is concluded that the numerical method employed has considerable potential for further investigations of rotating cavity flows
Kinematic Synthesis and Design of Non-Circular Gears Through a Symbolic-Numeric Modeling Approach
No full textThe paper presents a computational approach to the kinematic synthesis of non-circular gears. The two gears are assumed to be external, with parallel axes and with an average transmission ratio of -1. The symbolic expression adopted for the definition of the variable ratio input-output relation is first introduced. Then, by using as a computing environment a computer algebra software, the parametric expressions of the two pitch curves and their internal and external offset curves are directly generated.
The tooth conjugate profiles are obtained through an extension of the cycloidal tooth gearings to the case of non circular pitch curves. The implementation of the proposed method requires the solution of several mathematical problems. For example, the generation of the tooth profile equation requires the explicit parametric representation of the arc length of the pitch curves; the definition of each tooth height is determined by solving a system of two nonlinear equations obtained by intersecting the tooth profile curve with the curve offset from the pitch curve. Case by case, the paper discusses in detail the mathematical formulation and the adopted solution procedure: in general they take advantage of the chosen computing environment that allows a mixture of symbolic-numeric algorithms.
Criteria for the choice of design parameters (number of teeth, tooth height, radius of the rolling circle) and their influence on the resulting gears properties (contact ratio, pressure angle) are then discussed. Finally, some numerical examples are reported and manufacturing aspects discussed.The paper presents a new method for the kinematic synthesis of non-circular gears of general type, for a given law of motion. The proposed method is an extension of cycloidal gearings to the case of non-circular pitch curves. The computation procedure is based on a mixed symbolic-numeric approach that allows us to determine the equations of the curves representing the tooth shapes in parametric, explicit form. The evaluations of the pressure angle and of the contact ratio are discussed. A numerical example is presented. Copyright © 2005 by ASME
Comparação de modelos de análise das normas ASME e EN 1591 para o projeto de flanges com juntas circulares
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia MecânicaExistem vários métodos analíticos que apresentam modelos para determinar os esforços atuantes no flange em função de uma determinada carga de aperto necessária para vedação da conexão e em função da pressão interna e de outras forças atuantes. Foram selecionados três dos principais métodos analíticos aplicados em projeto de vasos e tubulações industriais: o método atual do ASME baseado nas constantes de gaxeta m e y necessárias para determinar a força de aperto requerida, o novo método proposto para o ASME identificado aqui como o método do PVRC baseado nas novas constantes de gaxeta Gb, a e Gs em substituição as constantes m e y, e o método do Comitê Europeu de Padronização identificado aqui como EN1591. Tanto o método do PVRC quanto o método do EN1591 foram desenvolvidos a partir de um conceito mais atualizado, na qual o valor da força requerida de aperto é determinado em função de uma determinada taxa de vazamento esperada, este conceito é diferente do praticado atualmente pelo método do ASME que não relaciona a força de aperto requerida com o desempenho de estanqueidade. Diferentes considerações de contorno e critérios de cálculo dos três métodos analíticos resultam em diferentes valores de tensão encontrados para o flange, o que pode acarretar em subdimensionamentos para determinadas aplicações. O quanto divergente são estes resultados entre si e com a situação real é o objetivo final deste trabalho que analisou os três métodos analíticos através da avaliação das forças consideradas e das tensões determinadas por cada um dos seus modelos, comparando-os entre si e com os resultados de métodos numéricos mais precisos, sendo que para este trabalho foi considerado o método dos elementos finitos. As forças de projeto dos métodos analíticos aplicadas ao método dos elementos finitos não resultaram em tensões que pudessem causar danos estruturais ao flange, já que as tensões se mantiveram dentro dos limites admissíveis para as diferentes categorias de tensão (primária e secundaria) da norma ASME de Vasos de Pressão. Contudo, foram detectados alguns aspectos dentro de cada um dos modelos analíticos que merecem ser reavaliados e consolidados em outras simulações envolvendo testes práticos de campo para somar a avaliação mecânica a uma avaliação de estanqueidade, pois, mesmo que não haja comprometimento estrutural dos flanges, o nível de deformação ao qual estão sujeitos pode comprometer o desempenho de estanqueidade do conjunto e, portanto, os resultados mecânicos não garantem a plena segurança da conexão, já que além de possuir integridade mecânica devem evitar vazamentos. The existing analytical models determine the applied loads to seal the connection as function of the bolt load, external forces and internal pressure. Three analytical methods were selected to applied in design of industrial pressure vessel and piping: actual method of the ASME with the gasket constants m and y, the new method proposed for ASME described as PVRC method with the new gaskets constants (Gb, a and Gs) and European method EN1591. The PVRC and EN1591 method were based on the new concept where the required operating and seating loads are function of maximum acceptable leak rate, by the way, the actual ASME method do not use this concept, the required forces are not based on a admissible leak rate. Different boundary conditions and criteria of calculation of the three methods obtain different stress values to the flanges that can results in failures to some cases. This work reviews the implications of these methods in design of the bolted flanges through a comparison of considered forces and stresses by this methods and with the results of finite element analysis. The design forces generate by the analytical methods do not cause mechanical damage because the resultants stresses are below of admissible limits for the stress categories (primary and secondary) of the Pressure Vessel ASME code. However, were identified some aspects inside each analytical method that must be reviewed through practical tests to add the results of this mechanical analysis with the sealing analysis, because the strains can to decrease the sealing performance of the connection. The mechanical results do not warranty the safety of the connection
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