A continual model of damaged media for describing the creep failure process

I.V. Volkov^∗ , L.A. Igumnov^∗∗ , S.Yu. Litvinchuk^∗∗∗

Research Institute of Mechanics, Lobachevsky National Research State University, Nizhny Novgorod, 603950 Russia

E-mail: ^∗pmptmvgavt@yandex.ru, ^∗∗igumnov@mech.unn.ru, ^∗∗∗litvinchuk@mech.unn.ru

Received October 1, 2019

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DOI: 10.26907/2541-7746.2019.4.509-525

For citation : Volkov I.V., Igumnov L.A., Litvinchuk S.Yu. A continual model of damaged media for describing the creep failure process. Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki, 2019, vol. 161, no. 4, pp. 509–525. doi: 10.26907/2541-7746.2019.4.509-525. (In Russian)

Abstract

The main laws of deformation and degradation processes of the initial strength properties of structural materials (metals and their alloys) according to the long-term strength mechanism were considered. From the viewpoint of the mechanics of damaged media (MDM), a mathematical model was created to describe inelastic deformation and damage accumulation during the creep process. An experimental and theoretical methodology for determining material parameters of the derived defining relations of MDM was developed. The material parameters and scalar functions of the MDM model, its reliability and the scope of its applicability were determined based on the analysis of the processes of deformation and failure of laboratory specimens in the conditions of soft loading (controlled stresses). The results of the experimental study of short-term creep of the VZh-159 heat-resistant alloy were presented. The process of deformation and damage accumulation was numerically analyzed; the obtained numerical results were compared with the data of the full-scale experiments. Comparison of the numerical and experimental data shows that the introduced defining relations of MDM adequately describe the response of materials in the conditions of degradation of the initial strength properties of structural materials according to the long-term strength mechanism.

Keywords: nonstationary creep, long-term strength, simulation, defining relations, mechanics of damaged media, temperature, damage, material parameter, numerical experiment, full-scale experiment

Acknowledgments. This work was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. 075-11-2019-050).

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