scholarly journals The opportunities of umbrella-type shells

2020 ◽  
Vol 16 (4) ◽  
pp. 271-278
Author(s):  
Sergey N. Krivoshapko
Keyword(s):  
Strain State ◽  
Strength Analysis ◽  
Thin Shells ◽  
Spatial Structures ◽  
Surfaces Of Revolution ◽  
Base Surface ◽  
New Information ◽  
Scientific Papers ◽  
Thin Walled

Relevance. The necessity of division of umbrella surfaces and surfaces of umbrella type into two separated classes is explained in introduction. Earlier, umbrella surfaces and surfaces of umbrella type were in the same class of surfaces because they consist of the identical fragments lying on the surfaces of revolution. Umbrella surfaces are compound surfaces on the base surface of revolution but umbrella-type surfaces are kinematic surfaces formed by continuous movement of a changing curve and that is why taking into account the methods of construction of these surfaces they were divided in two separate classes. The aim of the work is a collection of main publications on all areas of the investigation of umbrella-type shells. Methods. For the determination of principal results of investigation of umbrella-type shells, it is necessary to know differential geometry of surfaces, structural mechanics of thin shells, and approaches used in architecture of spatial structures. Results. In this article, the principal scientific papers on geometry, strength analysis, and offers of applications of thin-walled shells of umbrella type in building and of reflectors of umbrella type for space apparatuses. The accurate parametric equations of some determined surfaces are presented. The approximated computer models of middle surfaces of the real umbrella shells but in the form of umbrella-type surfaces are given. The examples of determination of stress-strain state of thin-walled shells of umbrella type without dividing of the whole shell in identical fragments are shown. New information and materials already known about shells of umbrella type give reasons to suppose that the shells of this type will be claimed by engineers and architects.

RESERVE OF ANALYTICAL SURFACES FOR ARCHITECTURE AND CONSTRUCTION

2021 ◽  
Vol 98 (6) ◽  
pp. 63-72
Author(s):  
GIL-OULBE MATHIEU ◽  
Keyword(s):  
Mechanical Engineering ◽  
Building Materials ◽  
Shell Structures ◽  
Housing Construction ◽  
Spatial Structures ◽  
Surfaces Of Revolution ◽  
Industrial Buildings ◽  
New Ideas ◽  
Wavy Surfaces ◽  
Thin Walled

After a period of relative calm in the construction and design of thin-walled large-span shells and network multilayer shell structures, which, according to the world's leading architects, began in the 1980 s, the time has come for the expanded use of spatial structures in the architecture of public and industrial buildings. Less commonly, shells are used in small-sized housing construction: ecological villages, noospheric and bionic architecture. The entire 20th century did not stop research on the development of analytical and numerical methods for analyzing shells for strength and stability, for the creation of new building materials. Geometers have created and studied more than 600 analytical surfaces that can be mistaken for the mid-surfaces of civil and mechanical engineering shells. As a result, by the beginning of the 21st century, architects and engineers had all the necessary tools to continue the traditions of the "golden age of shells". The analysis of problems with the use of new forms in parametric architecture, carried out in the article, showed that more than ten classes of surfaces from their classification have not yet found application in architecture and mechanical engineering. It is assumed that the number of applied classes of surfaces will not expand, and new ideas for the shaping of shells will be based on the use of already well-known surfaces, namely, surfaces of revolution, transfer, umbrella, minimal, ruled and wavy surfaces. Mainly, shell structures will be designed taking into account environmental, energy-saving requirements and transforming structures.

Stress and Strain State of a Gas Pipeline in Conditions of Stress-Corrosion

1996 ◽  
Author(s):  
V. V. Kharionovsky ◽  
V. P. Tcherni
Keyword(s):  
Stress Corrosion ◽  
Cross Sections ◽  
Stress Corrosion Cracking ◽  
Strain State ◽  
Gas Pipeline ◽  
Thin Shells ◽  
Stress And Strain ◽  
Residual Strains

It is shown that in the analysis of causes of stress corrosion cracking (SCC) of gas pipeline (GP) insufficient attention is paid to the role of mechanical stresses. In the paper it is underlined that by consideration of SCC causes it is necessary to take into account real distortions of the form of cross-sections of a pipeline. These are ovality of cross-sections and, the main, dents. Conditions of occurrence of these defects of the form of cross-sections of pipes are considered. The kinds of stress and strain state (SSS) in GP are analysed. The techniques are developed of assessment of the level of residual strains in the area of distortions of the form of cross-sections of pipelines as well as of determination of stresses and strains in them at action of internal pressure. The technique is based on the theory of elastic thin shells. It is shown that through-wall -thickness stresses which were ontained by the technique can considerably exceed the yield stress of steel even for shallow dents. Conclusions are given about necessity to account for stresses in GP in the analysis of SCC causes as well as about necessity of standardizing allowable levels of these stresses.

scholarly journals Analytical ruled surfaces and their complete classification

2020 ◽  
Vol 16 (2) ◽  
pp. 131-138
Author(s):  
Sergey N. Krivoshapko
Keyword(s):  
Strain State ◽  
Complete Classification ◽  
Point Of View ◽  
Ruled Surfaces ◽  
Stress Strain ◽  
Technical Literature ◽  
Graphic Form ◽  
Methods Of Determination ◽  
Thin Walled

The aim of the work - to give the possibility to expand mind of designers and architects projecting structures in the form of traditional and non-canonical ruled surfaces. These surfaces have several unquestionable advantages with a point of view of their forming, designing, and making of factory-made goods and erections in the form of ruled surfaces and analysis methods. Methods. Choosing ruled surfaces for classification, one can use methods of their determination by vector, parametrical, implicit, and in explicit equations. Only analytical ruled surfaces are considered which were examined and presented in scientific-and-technical literature. Results. All known at present time ruled surfaces are given in a graphic form. The determinations of some little known ruled surfaces are presented in a paper. The original sources, where these surfaces are examined or their application in real structures and erections are considered, or methods of determination of stress-strain state in thin-walled shells with ruled middle surfaces are presented, are given in references.

Static Analysis of Shells With Developable Middle Surfaces

1998 ◽  
Vol 51 (12) ◽  
pp. 731-746 ◽  
Author(s):  
S. N. Krivoshapko
Keyword(s):  
Numerical Methods ◽  
Static Analysis ◽  
Strain State ◽  
A Priori ◽  
Middle Surface ◽  
Review Article ◽  
Strength Analysis ◽  
Thin Shells ◽  
Principal Curvatures ◽  
Elastic Shells

This review article is devoted to an analysis of the literature on the stress-strain state of shells with developable middle surfaces. Wide choices of design methods for the developable surfaces provide not only the necessary shapes and special properties; they also prove to be convenient to apply. Representative examples are given for the static analysis of thin elastic shells by both analytic and numerical methods. Generally, the curvilinear non-orthogonal conjugate coordinates of the developable middle surface are used. Lines of principal curvatures are used as coordinates only for the strength analysis of thin shells in the form of Monge’s ruled surfaces. It is shown that momentless and moment theories give similar results if certain conditions are met a priori. The parabolic (isometric) bending of thin developable shells is also analyzed. This review article contains 97 references.

Trial production of γ-type energy filtering TEM

1995 ◽  
Vol 53 ◽  
pp. 604-605
Author(s):  
Y. Taniguchi ◽  
E. Nakazawa ◽  
S. Taya
Keyword(s):  
Magnetic Energy ◽  
Electron Optics ◽  
Electron Microscopic ◽  
Mass Spectrometers ◽  
Ion Optics ◽  
Energy Filtering ◽  
New Information ◽  
New Type ◽  
Fringing Fields

Imaging energy filters can add new information to electron microscopic images with respect to energy-axis, so-called electron spectroscopic imaging (ESI). Recently, many good results have been reported using this imaging technique. ESI also allows high-contrast observation of unstained biological samples, becoming a trend of the field of morphology. We manufactured a new type of energy filter as a trial production. This energy filter consists of two magnets, and we call γ-filter since the trajectory of electrons shows ‘γ’-shape inside the filter. We evaluated the new energyγ-filter TEM with the γ-filter.Figure 1 shows schematic view of the electron optics of the γ-type energy filter. For the determination of the electron-optics of the γ-type energy filter, we used the TRIO (Third Order Ion Optics) program which has been developed for the design of high resolution mass spectrometers. The TRIO takes the extended fringing fields (EFF) into consideration. EFF makes it difficult to design magnetic energy filters with magnetic sector fields.

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