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Research of longevity of the centrally compressed bars with changing geometrical characteristics

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Category: Geotechnical and mining mechanical engineering, machine building

Last Updated on 24 July 2014

Published on 10 July 2013

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Authors:

A.P. Ivanova, Cand. Sci. (Tech.), Associate Professor, State Higher Educational Institution “National Mining University”, Associate Professor of the Department of Construction and Geomechanics, Dnipropetrovsk, Ukraine

Abstract:

Purpose. Increasing of reliability, maintainability and longevity of the metallic cored constructions, and also declining of their material capacity.

Methods. Basis of researches consists of treatment and analysis of results of inspection of the technical state of the cored construction, study of the problems of constructions, working in aggressive environment. The estimation of bars longevity largely becomes complicated by the necessity of determination of the minimal inertia moment and the position of the main central axes which can be changed due to corrosion in course of time. The mathematical model of corrosive wear, which takes into account these changes, is used in this scientific work.

Results. In real constructions the failure of any element can happen not only as a result of achievement of tensions of limit value, but also as a result of loss of stability in case of a bar compression.

The task of the optimal planning of the cored elements of different types with geometrical parameters, which change due to a corrosion, is considered. The influence of parameters of aggressive environment and the level of loading on the sizes of bars cross-section is investigated. The dependence of the compressed bars lifetime on their length for different types of loading is  graphically illustrated.

Originality. The received formulas  allow to take into account the change  in location of the gravity center, the orientations of main axes and the minimum moments of inertia in bars. The dependence of the length of different types compressed bars on their lifetime, particularly which of the following limitations comes into a force: that according to sturdiness or according to solidity or both of them are valid.

Practical value. The value of parameter of damage, corresponding to the moment of exhausting of bearing strength for the compressed bars, is obtained.

References:

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Ovchinnikov, I.G., Dvorkin, M.S. and Sabitov, KH. A. (1993), “Bank of mathematical models of corrosive wear, applied for forecasting of metallic constructions behavior”, Problemy prochnosti materialov I konstruktsiy, vzaimodeystvuyushchikh s agressibnymi sredami, Mezhvuzovskiy nauchnyu sbornik, SGTU, Saratov, pp. 141 – 150.

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 Zelentsov, D.G. and Solodkaya, N.A. (2002), “Longevity of the beam, subject to the corrosive wear under limitations on rigidity”, Naukovyi visnyk Natsionalnoyi hirnychoyi akademii Ukrayiny, no.2, pp. 45 – 47.

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