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RISS 인기검색어
- 검색키워드
- 저자 : M. Cuadrado (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Modeling the Calculation of Lateral Accelerations in Railway Vehicles as a Tool of Alignment Design
J. Nasarre,M. Cuadrado,P. Gonzalez Requejo,E. Romo,C. Zamorano 한국철도학회 2009 International Journal of Railway Vol.2 No.3
Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these normative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.
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Modeling the Calculation of Lateral Accelerations in Railway Vehicles as a Tool of Alignment Design
Nasarre, J.,Cuadrado, M.,Requejo, P.Gonzalez,Romo, E.,Zamorano, C. The Korean Society for Railway 2009 International Journal of Railway Vol.2 No.3
Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.
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Dual-steel Portal Frame Design to Withstand a Fire Exposure of 45 Minutes
H. García,M. V. Biezma,J. Cuadrado,M. Zubizarreta 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.3
This paper presents the design of industrial portal frames with plain carbon steel (S275) and micro-alloyed Fire Resistant (FR) steel, coated with intumescent paint as fire protection for the structure. The coating improves the overall heat resistance of the metallic structure. The portal frames with different spans were calculated to observe their fire behavior. The structure was dimensioned by estimating the stresses to which each particular structural section was subjected and by selecting the most economic combination. The process was then repeated with the new dimensions to reach an optimal structural design. The key variables analyzed in this study are: five different spans, seven intumescent paint thicknesses, and eleven price ratios between the FR and the S275 steels, considering a fire exposure time of 45 minutes in all of the scenarios under study. The main conclusion was that the use of FR combined with S275 and the intumescent paint system was the most profitable option. In many cases, the better performance of this combination offered the most technically feasible option for the design of portal frame steel structures.
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IRK vs Structural Integrators for Real-Time Applications in MBS
D. Dopico,U. Lugris,M. Gonzalez,J. Cuadrado 대한기계학회 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.1S
Recently, the authors have developed a method for real-time dynamics of multibody systems, which combines a semi-recursive formulation to derive the equations of motion in dependent relative coordinates, along with an augmented Lagrangian technique to Impose the loop closure conditions The following numerical Integration procedures, which can be grouped Into the so-called structural integrators, were tested trapezoidal rule, Newmark dissipative schemes, HHT rule, and the Generalized-a family It was shown that, for large multibody systems, Newmark dissipative was the best election Since, provided that the adequate parameters were chosen, excellent behavior was achieved in terms of efficiency and robustness with acceptable leveh of accuracy In the present paper, the performance of the described method in combination with another group of integrators, the Implicit Runge-Kutta family (IRK), is analyzed The purpose is to clanfy which kind of IRK algorithms can be more suitable for real-time applications, and to see whether they can be competitive With the already tested structural family of integrators<br/> The final objective of the work is to provide some practical criteria for those interested in achieving real-time performance for large and complex multi body systems<br/>
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