Kinetic Theory of Creep and Creep-Rupture Strength Analysis of Structural Components. Part 1. Stress-Strain State in Nonuniformly Heated Thick-Walled Pipes

2005 ◽  
Vol 37 (5) ◽  
pp. 460-470 ◽  
Author(s):  
A. F. Nikitenko ◽  
I. V. Lyubashevskaya
Author(s):  
P. Popovych ◽  
L. Poberezhny ◽  
O. Shevchuk ◽  
I. Murovanyi ◽  
T. Dovbush ◽  
...  

Purpose: Development of a computational model of stress-strain state bearing elements of trailer frames for preliminary assessment and identification of areas with increased risk of failure. Design/methodology/approach: The object of the study is the processes of loading the load-bearing metal structures of trailers - fertilizer spreaders. The stress-strain state of the spreader bearing system is investigated for the established three typical cases of external load. To refine the values obtained as a result of modelling, they were determined in SOLIDWORKS. Findings: Computational models of load have been compiled by improving the method of minimum potential deformation energy for its effective correct use in analytical studies of a similar type of metal structures. It is proved that for a flat closed frame structure made of thin-walled profiles, loaded with forces perpendicular to the plane of the frame, the levelling of compression and shear energies, as well as axial and transverse forces and bending moments in the horizontal plane does not significantly affect the calculation results. Research limitations/implications: Horizontal components of the shear forces as well as the normal forces and as a consequence the corresponding potential deformation energy are neglected, which has some effect on the accuracy of the calculations. Practical implications: An effective tool for strength analysis with preliminary assessment and diagnostics of load-bearing metal structures based on the constructed calculation models of stress strain state load-bearing frames of typical geometry with an arbitrarily given distribution of external load. Originality/value: A universal algorithm for recording additive functions of bending and torques, as well as the potential deformation energy of welded frames of trailers.


Author(s):  
S. V. Yushchube ◽  
I. I. Podshivalov

The determination of mobility of the concrete foundation on a natural subgrade is rather relevant for the strength analysis of multistory brick buildings with a spatial cross-wall structural system. During the inelastic soil behavior, its ultimate limit and elastoplastic states are allowable along the concrete foundation perimeter, the bearing capacity of the foundation being provided as a whole. In this case, it is important to adhere to the standard conditions of the foundation deformation and mobility. The finite element modeling of the stress-strain state of the concrete foundation and the building superstructure of the base-foundation-building system is performed in the MicroFe software package. A consideration of inelastic soil deformations in the natural subgrade results in unacceptable displacements of the concrete foundation.


2011 ◽  
Vol 17 (4) ◽  
pp. 558-568 ◽  
Author(s):  
Romanas Karkauskas ◽  
Michail Popov

The establishment of the real stress-strain state of the structure is one of the most important problems for designing and undertaking the reconstruction of building constructions as well as making calculations for the purpose of optimizing cross-sections of various structural elements. This task can be achieved by analysing the structure as a geometrically nonlinear system (refusing an assumption of small displacements) and taking into consideration plastic deformations. Modern computer technologies and mathematical tools enable us to perform strength analysis of space structures and to increase the accuracy of stress-strain state analysis. The present paper develops a technique for constructing a finite element tangent matrix for the nonlinear analysis of the space frame structure aimed at determining plastic deformations. The mathematical models of the problems based on static and kinematic formulations using the dual theory of mathematical programming were created for analysis. Strength conditions presented in construction codes and specifications AISCLRFD and suggested by other researchers (e.g. Orbison's strength conditions) are used in the formulations of the analysed problems. The mathematical models of the considered problems are tested by calculating a two-storied space frame. The results of the performed analysis are compared with data obtained within the studies conducted by other researchers. Santrauka Projektuojant ar rekonstruojant konstrukcijas, atliekant jos elementų skerspjūvių optimizavimo skaičiavimus, vienas iš svarbiausių uždavinių – konstrukcijos tikrojo įtempto deformuoto būvio (ĮDB) nustatymas. Tai galima pasiekti atliekant konstrukcijos kaip geometriškai netiesinės sistemos (atsisakant mažų poslinkių prielaidos) analizę, įvertinant plastines deformacijas. Taikant šiuolaikines kompiuterines technologijas ir matematinį aparatą, tapo įmanoma vykdyti erdvinės konstrukcijos stiprumo analizę ir padidinti konstrukcijos ĮDB analizės tikslumą. Tuo tikslu šiame darbe toliau plėtojama tangentinės standumo matricos sudarymo metodika erdvinės rėminės konstrukcijos netiesinei analizei, įvertinant plastines deformacijas. Naudojant matematinio programavimo dualumo teoriją sudaryti analizės statinės ir kinematinės formuluočių uždavinių matematiniai modeliai. Naudojamos AISC-LRFD normatyviniuose dokumentuose pateiktos ir kitų autorių (pavyzdžiui, Orbison) pasiūlytos stiprumo sąlygos. Suformuluoti analizės uždavinių matematiniai modeliai buvo aprobuoti skaičiuojant dviejų aukštų erdvinį rėmą. Gauti analizės rezultatai palyginti su eksperimentiniais ir kitų autorių analitiniais rezultatais.


Author(s):  
Yaroslav Dubyk ◽  
Vladislav Filonov ◽  
Yuliia Filonova ◽  
Olexander Kovalenko

Abstract The analysis of deteriorated heat transfer (DHT) influence on the stress-strain state of a perspective core of Small Modular Reactors with Supercritical Water (SMR SCWR) fuel assemblies is carried out, based on experimental and numerical data. Experimental data for 3- and 7-rod assemblies of 600 mm height with twisting spacer screws, on which deterioration heat transfer regimes were observed. The analysis of the stress-strain state was performed for two cases of temperature field. In the first variant, the temperature field is estimated using Computational Fluid Dynamics (CFD) with low-Re effects accounting, which allows obtaining the maximum temperature, but incorrectly estimates the axial profile. In the second case, an experimental profile with an averaged tangential temperature value is considered. Strength analysis is performed using the developed numerical-analytical mechanical model of the rod assembly. Obtained results make it possible to establish what is more important for assessing the safety of perspective reactors: a conservative estimate of the maximum wall temperature or its local distribution.


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