Structural Optimization Under Buckling Constraints Using Frame Elements with Anisotropic Cross Sections

2017 ◽  
pp. 1394-1410
Author(s):  
Florian Mitjana ◽  
Sonia Cafieri ◽  
Florian Bugarin ◽  
Christian Gogu ◽  
Fabien Castanie
Keyword(s):  
Structural Optimization ◽  
Cross Sections ◽  
Buckling Constraints

Linear Solar Concentrator Structural Optimization Using Variable Beam Cross Sections

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Moucun Yang ◽  
Yuezhao Zhu ◽  
Wei Fu ◽  
Garth Pearce ◽  
Robert A. Taylor
Keyword(s):  
Structural Optimization ◽  
Cross Sections ◽  
Cost Savings ◽  
Variable Cross Section ◽  
Optimization Approach ◽  
Variable Cross ◽  
Cross Sectional ◽  
Optical Efficiency ◽  
Metal Grid ◽  
Box Structure

The design and construction of solar concentrators heavily affects their optical efficiency, heat utilization, and cost. Current trough concentrators use an equivalent uniform beam with a metal grid substructure. In this conventional design, there is surplus stiffness and strength, which unnecessarily increases the overall weight and cost of the structure. This paper describes a variable cross section structural optimization approach (with the EuroTrough design, including safety factors, taken as an example) to overcome this issue. The main improvement of this design comes from keeping the beams rigid and strong near the two ends (at the torque box structure) while allowing the middle of the structure to be relatively weak. Reducing the cross-sectional area of the middle beams not only reduces the amount of material needed for the structure but also reduces the deflection of the reflector. In addition, a new connection structure between two neighboring concentrator elements was designed to reinforce the structure. The simulated results show that the concentrator's structural weight (including the torque box, endplates, and cantilever arms) is reduced by 13.5% (i.e., about 133 kg per 12 m long element). This represents a meaningful capital and installation cost savings while at the same time improving the optical efficiency.

scholarly journals Considerations on the dimensioning of columns with dimensions less than that established by NBR 6118 (ABNT, 2014)

2021 ◽  
Vol 10 (5) ◽  
pp. e4710514575
Author(s):  
Renan Gustavo Pacheco Soares ◽  
Gustavo Gutierrez de Oliveira Rodrigues ◽  
Erivan Mendes da Paz ◽  
Carla Renata Xavier Pacheco ◽  
Lyneker Souza de Moura ◽  
...  
Keyword(s):  
Structural Optimization ◽  
Cross Section ◽  
Cross Sections ◽  
Cost Reduction ◽  
Design Methods ◽  
Normative Standards

The search for methods that provide savings greatly drives the search for alternatives when it comes to cost reduction. The obsession with aesthetics and cheaper alternatives for civil construction, can lead to unexpected and dangerous results. The reduction of the dimensions of the columns can be done consciously, always keeping in mind the compliance with normative standards combined with structural optimization. The objective of this work was to evaluate the efforts resulting from the reduction of the minimum dimensions beyond that established by NBR 6118 (ABNT, 2014) and compare with the considerations of NBR 15575 (ABNT, 2013) about a possible permission to reduce the minimum dimensions of columns. For this, the software MathCAD, Eberick and SAP2000 were used to implement the calculation and design methods of the columns. The variables evaluated were the steel area of ​​columns with different cross sections, length of buckling and the necessary anchoring length that a beam would need to anchor in the columns. As a result, it was found that in relation to the steel area, the decrease in the section resulted in increases in the steel area. The buckling was not acceptable (λ> 140) with a cross-section column less than 19 cm for situations of double height up to 6 m in height, according to NBR 15575 cites. The criterion of anchoring the beam reinforcement in a column with section smaller than 14 cm was not feasible for all situations.

scholarly journals Topological gradient in structural optimization under stress and buckling constraints

2021 ◽  
pp. 126032
Author(s):  
F. Mitjana ◽  
S. Cafieri ◽  
F. Bugarin ◽  
S. Segonds ◽  
F. Castanie ◽  
...  
Keyword(s):  
Structural Optimization ◽  
Buckling Constraints ◽  
Topological Gradient

scholarly journals Structural optimization of concrete plane frames considering the static and dynamic wind effect

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Emanuely Ugulino Cardoso ◽  
Rene Quispe Rodríguez ◽  
Lucas Queiroz Machado ◽  
Felipe Faustino Kunz ◽  
Patrick dos Santos e Santos ◽  
...  
Keyword(s):  
Structural Optimization ◽  
Cross Sections ◽  
Optimization Method ◽  
Wind Effect ◽  
Dynamic Effects ◽  
Plane Frames ◽  
Realistic Representation ◽  
Applied Forces ◽  
The Difference ◽  
Teaching Learning

abstract: This study has as its main purpose the structural optimization of plane frames in concrete, having as the objective function the minimum total weight of the structure. For this purpose, external actions, considered within the optimization process, are intended to represent accurately all effects observed in a real situation. In such manner, loads are dependent on the cross-section obtained in each optimization step, as well as the static and dynamic effects of the wind are considered for a more realistic representation. The optimization method adopted is the Teaching-Learning Based Optimization (TLBO). Thus, all proper design constraints were considered in accordance with Brazilian standards for concrete structures. From the results obtained in both situations (static and dynamic effects), it is possible to notice the difference regarding external actions, in which higher loads were obtained in higher floors, using the simplified dynamic model proposed in standards. Regarding the analysis of the structure optimization, the weight was higher when the applied forces were the result of the dynamic wind model, in which the larger cross-sections were found at the bottom of the structure. Even though this may be a well-known issue, the present work shows a quantitative study in which both effects are discussed in detail, as well as it features a methodology, based on a novel optimization method and with a straightforward implementation, that could be adapted for the analysis of more complex structures.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 486-487
Author(s):  
Mihir Parikh
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Cross Sections ◽  
Resolving Power ◽  
Peak Intensity ◽  
Molecular Film ◽  
Resolution Electron ◽  
Dissociation Cross Section ◽  
High Resolution Electron Microscope ◽  
The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

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