scholarly journals An Optimization Procedure for Overhead Gantry Crane Exposed to Buckling and Yield Criteria

2017 ◽  
Vol 8 (2) ◽  
pp. 28
Author(s):  
Ali Ahmid ◽  
Van N. Le ◽  
Thien M. Dao
Keyword(s):  
Cross Section ◽  
Real Life ◽  
Local Buckling ◽  
Beam Theory ◽  
Optimization Procedure ◽  
Element Model ◽  
Gantry Crane ◽  
Rectangular Plates ◽  
Cross Section Area ◽  
Structural Applications

<p>The current study presents a general optimization procedure that could be used in designing of various structural applications. To validate the performance of the proposed procedure, a real life application of a custom welded I-Beam gantry crane is selected. The crane is composed of three rectangular plates with the same length and different thicknesses and widths welded together by full penetration welds over the span length to form an I-Beam profile. The thicknesses and widths of plates are to be optimized to have the minimum cross section area while respecting yield, buckling, deflection and fatigue criteria. A mathematical procedure based on Timoshenko beam theory and Crane Manufacturers Association of America (CMAA) in combination with the Genetic Algorithm (GA) is presented, and a Mathcad code is implemented to find the optimal I-Beam cross section dimensions. Nine examples are introduced for 8, 12 and 20 m crane span subjected to 10, 20 and 40-toncapacities. It is noticed that the optimized I-section configurations always show narrow and thick lower flange, wider and thinner upper flange and tall and very thin web. Theupper flange local buckling and the lateral buckling limits are achieved for all nine cases, 75% of cases for the web buckling limit, about 33% of cases for the fatigue and yield limits whereas the maximum deflection constraint is never critical. The obtained results were verified using ANSYS Workbench software with a 3D Solid Finite Element model and shown good agreement, which confirms that the proposed procedure is efficient.</p>

Flexural Behavior of Pultruded GFRP Deck Panels with Snap-Fit Connections

2018 ◽  
Vol 18 (02) ◽  
pp. 1850019 ◽  
Author(s):  
Mário F. Sá ◽  
Augusto M. Gomes ◽  
João R. Correia ◽  
Nuno Silvestre
Keyword(s):  
Cross Section ◽  
Glass Fibers ◽  
Three Dimensional ◽  
Local Buckling ◽  
Beam Theory ◽  
Flexural Behavior ◽  
Deck Panels ◽  
Analytical Formulae ◽  
Shell Finite Element ◽  
Failure Conditions

This paper presents experimental, analytical and numerical investigations about the flexural behavior of glass fiber reinforced polymer (GFRP) pultruded panels for footbridge decks. The analyzed panels, made of isophthalic polyester and E-glass fibers, comprise a multicellular thin-walled cross-section with panel-to-panel vertical snap-fit connections at their lateral edges. As part of a comprehensive study about the mechanical and structural behavior of this type of footbridge decks, the experimental study presented here addresses: (i) the mechanical characterization of the laminated material, and (ii) the quasi-static flexural behavior of the panels for both service and failure conditions. The experimental data obtained is used to validate and assess the accuracy of three-dimensional shell finite element (FE) models and analytical formulae. Particular focus is given to the serviceability and failure performance of the panels, in terms of their deformability and susceptibility to buckling phenomena, respectively. Regarding the serviceability behavior, the results obtained in this study demonstrate the importance of duly specifying the shear coefficient of the multicellular cross-section on Timoshenko beam theory, in order to obtain accurate deflection predictions. In terms of failure performance, both the flexural tests and the analytical formulae indicate that the local buckling of the compressive flanges seems to have triggered the collapse of the tested panels, thus limiting their load carrying capacity. The geometrically nonlinear FE analyses allowed understanding in further depth the ultimate behavior of the panels, providing further insights about their failure mechanisms.

Experimental Investigation of the Deformation of Built-up Members of Cold-Formed Steel Profiles

2011 ◽  
Vol 70 ◽  
pp. 416-421 ◽  
Author(s):  
Iveta Georgieva ◽  
Luc Schueremans ◽  
Guido De Roeck ◽  
Lincy Pyl
Keyword(s):  
Cross Section ◽  
Local Buckling ◽  
Element Model ◽  
Mode Shapes ◽  
European Standard ◽  
Distortional Buckling ◽  
Buckling Mode ◽  
Measuring Device ◽  
Measuring Techniques ◽  
Cold Formed Steel

Built-up members of cold-formed steel (CFS) profiles were tested in 4-point bending. CFS profiles (generally thin-walled) deform considerably under load, and the deformed configuration is a result of the superposition of different buckling mode shapes. Local buckling propagates through the profile walls; during distortional buckling parts of the cross-section rotate around a web-flange juncture. Alongside the buckling effects, the overall deformation of the member is considerable. To study these slender and relatively long members, a sufficient number of measuring positions on the specimens is needed. Often, this is not feasible with the conventional measuring techniques. An optical measuring device was used to record the movement of a large number of points per specimen. The obtained results are placed in a 3D coordinate system and can be exported for further data processing. The goal of the measurement campaign was to calibrate a Finite Element model that will simulate the tests. The model will be used for the analysis of composed frame members of CFS profiles, whose design is not entirely covered by the European Standard [1]. After calibration, the FEA predicts the performance of these built-up members well.

scholarly journals Pareto-Optimization of HTS CICC for High-Current Applications in Self-Field

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Giordano Tomassetti ◽  
Gianluca de Marzi ◽  
Giuseppe Celentano ◽  
Francesco Rizzo ◽  
Andrea Augieri ◽  
...  
Keyword(s):  
Cross Section ◽  
Current Density ◽  
Power Transmission ◽  
Search Algorithm ◽  
Optimization Procedure ◽  
Element Model ◽  
Operating Conditions ◽  
Coated Conductors ◽  
Total Current ◽  
The Cross

The ENEA superconductivity laboratory developed a novel design for Cable-in-Conduit Conductors (CICCs) comprised of stacks of 2nd-generation REBCO coated conductors. In its original version, the cable was made up of 150 HTS tapes distributed in five slots, twisted along an aluminum core. In this work, taking advantage of a 2D finite element model, able to estimate the cable’s current distribution in the cross-section, a multiobjective optimization procedure was implemented. The aim of optimization was to simultaneously maximize both engineering current density and total current flowing inside the tapes when operating in self-field, by varying the cross-section layout. Since the optimization process involved both integer and real geometrical variables, the choice of an evolutionary search algorithm was strictly necessary. The use of an evolutionary algorithm in the frame of a multiple objective optimization made it an obliged choice to numerically approach the problem using a nonstandard fast-converging optimization algorithm. By means of this algorithm, the Pareto frontiers for the different configurations were calculated, providing a powerful tool for the designer to achieve the desired preliminary operating conditions in terms of engineering current density and/or total current, depending on the specific application field, that is, power transmission cable and bus bar systems.

Analytical and High-Resolution EM Study of Crystalline Phases formed at Metal-Ceramic Interface

1990 ◽  
Vol 48 (2) ◽  
pp. 426-427
Author(s):  
N. Merk ◽  
A. P. Tomsia ◽  
G. Thomas
Keyword(s):  
Cross Section ◽  
Dissimilar Materials ◽  
Ceramic Materials ◽  
Electron Micrograph ◽  
Scanning Electron Micrograph ◽  
Structural Applications ◽  
Metal Ceramic ◽  
The Subject ◽  
Ceramic Compounds ◽  
Scanning Electron

A recent development of new ceramic materials for structural applications involves the joining of ceramic compounds to metals. Due to the wetting problem, an interlayer material (brazing alloy) is generally used to achieve the bonding. The nature of the interfaces between such dissimilar materials is the subject of intensive studies and is of utmost importance to obtain a controlled microstructure at the discontinuities to satisfy the demanding properties for engineering applications . The brazing alloy is generally ductile and hence, does not readily fracture. It must also wett the ceramic with similar thermal expansion coefficient to avoid large stresses at joints. In the present work we study mullite-molybdenum composites using a brazing alloy for the weldment.A scanning electron micrograph from the cross section of the joining sequence studied here is presented in Fig. 1.

First and Second Order Elastoplastic Analyses of Thin-Walled Metal Members using Generalized Beam Theory

2018 ◽  
Author(s):  
Miguel Abambres
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cross Section ◽  
Beam Theory ◽  
Second Order ◽  
Flow Rule ◽  
Non Linear ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalized Beam Theory

Original Generalized Beam Theory (GBT) formulations for elastoplastic first and second order (postbuckling) analyses of thin-walled members are proposed, based on the J2 theory with associated flow rule, and valid for (i) arbitrary residual stress and geometric imperfection distributions, (ii) non-linear isotropic materials (e.g., carbon/stainless steel), and (iii) arbitrary deformation patterns (e.g., global, local, distortional, shear). The cross-section analysis is based on the formulation by Silva (2013), but adopts five types of nodal degrees of freedom (d.o.f.) – one of them (warping rotation) is an innovation of present work and allows the use of cubic polynomials (instead of linear functions) to approximate the warping profiles in each sub-plate. The formulations are validated by presenting various illustrative examples involving beams and columns characterized by several cross-section types (open, closed, (un) branched), materials (bi-linear or non-linear – e.g., stainless steel) and boundary conditions. The GBT results (equilibrium paths, stress/displacement distributions and collapse mechanisms) are validated by comparison with those obtained from shell finite element analyses. It is observed that the results are globally very similar with only 9% and 21% (1st and 2nd order) of the d.o.f. numbers required by the shell finite element models. Moreover, the GBT unique modal nature is highlighted by means of modal participation diagrams and amplitude functions, as well as analyses based on different deformation mode sets, providing an in-depth insight on the member behavioural mechanics in both elastic and inelastic regimes.

The Numerical Analysis of Contaminant Migration from Sanitary Landfill Sites

1977 ◽  
Vol 12 (1) ◽  
pp. 233-255
Author(s):  
J.F. Sykes ◽  
A.J. Crutcher
Keyword(s):  
Contaminant Transport ◽  
Cross Section ◽  
Element Model ◽  
Sanitary Landfill ◽  
Saturated Porous Media ◽  
Two Dimensional ◽  
Contaminant Migration ◽  
Southern Ontario ◽  
Galerkin Finite Element ◽  
Chloride Concentrations

Abstract A two-dimensional Galerkin finite element model for flow and contaminant transport in variably saturated porous media is used to analyze the transport of chlorides from a sanitary landfill located in Southern Ontario. A representative cross-section is selected for the analysis. Predicted chloride concentrations are presented for the cross section at various horizon years.

Thermoacoustic Shape Optimization of a Subsonic Nozzle

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Alexis Giauque ◽  
Maxime Huet ◽  
Franck Clero ◽  
Sébastien Ducruix ◽  
Franck Richecoeur
Keyword(s):  
Acoustic Emission ◽  
Cross Section ◽  
Source Term ◽  
Combustion Noise ◽  
Noise Emission ◽  
Cross Section Area ◽  
Section Area ◽  
The Cross ◽  
Nozzle Flows ◽  
Subsonic Nozzle

Indirect combustion noise originates from the acceleration of nonuniform temperature or high vorticity regions when convected through a nozzle or a turbine. In a recent contribution (Giauque et al., 2012, “Analytical Analysis of Indirect Combustion Noise in Subcritical Nozzles,” ASME J. Eng. Gas Turbies Power, 134(11), p. 111202) the authors have presented an analytical thermoacoustic model providing the indirect combustion noise generated by a subcritical nozzle when forced with entropy waves. This model explicitly takes into account the effect of the local changes in the cross-section area along the configuration of interest. In this article, the authors introduce this model into an optimization procedure in order to minimize or maximize the thermoacoustic noise emitted by arbitrarily shaped nozzles operating under subsonic conditions. Each component of the complete algorithm is described in detail. The evolution of the cross-section changes are introduced using Bezier's splines, which provide the necessary freedom to actually achieve arbitrary shapes. Bezier's polar coordinates constitute the parameters defining the geometry of a given individual nozzle. Starting from a population of nozzles of random shapes, it is shown that a specifically designed genetic optimization algorithm coupled with the analytical model converges at will toward a quieter or noisier population. As already described by Bloy (Bloy, 1979, “The Pressure Waves Produced by the Convection of Temperature Disturbances in High Subsonic Nozzle Flows,” J. Fluid Mech., 94(3), pp. 465–475), the results therefore confirm the significant dependence of the indirect combustion noise with respect to the shape of the nozzle, even when the operating regime is kept constant. It appears that the quietest nozzle profile evolves almost linearly along its converging and diverging sections, leading to a square evolution of the cross-section area. Providing insight into the underlying physical reason leading to the difference in the noise emission between two extreme individuals, the integral value of the source term of the equation describing the behavior of the acoustic pressure of the nozzle is considered. It is shown that its evolution with the frequency can be related to the global acoustic emission. Strong evidence suggest that the noise emission increases as the source term in the converging and diverging parts less compensate each other. The main result of this article is the definition and proposition of an acoustic emission factor, which can be used as a surrogate to the complex determination of the exact acoustic levels in the nozzle for the thermoacoustic shape optimization of nozzle flows. This acoustic emission factor, which is much faster to compute, only involves the knowledge of the evolution of the cross-section area and the inlet thermodynamic and velocity characteristics to be computed.

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