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ISSN 2227-6858
English version IS Bulletin Archive 2017. N 2/31


Shipbuilding

DOI.org/10.5281/zenodo.807781

Molokov K., Novikov V., Kitaev M.

KONSTANTIN MOLOKOV, Candidate of Engineering Sciences, Associate Professor, Department of Welding, e‑mail: spektrum011277@gmail.com
VALERY NOVIKOV, Candidate of Engineering Sciences, Associate Professor, e-mail: Leka1551@rambler.ru;
MAKSIM KITAEV, Candidate of Engineering Sciences, Senior Lecturer, e-mail: maxkit@mail.ru, Department of Shipbuilding and Ocean Technique
School of Engineering
Far Eastern Federal University
8 Sukhanova St., Vladivostok, Russia, 690091

Life cycle of welded joints and structural damages of steel under cyclic loads

Abstract: The adequate maintenance of the ship’s hull and its units are key factors that secure safe and efficient operation of the vessel. It seems necessary to have methods of calculation enabling one to exert operational control over technical condition of the ship. The method advanced by G. Kazanov is the best one for this purpose. It is based on the study of the history of the structural damages of the ship hull steel caused by cyclic loads. In this connection, the authors believe it necessary to establish mutual relationships between the sizes of the defect in wielded joints, parameters of cyclic loadings and the duration of the stages of fatigue failure. It has been found that the duration ratio of the second to the first damage stages has the constant value on conditions that the external load of symmetric cycle is equal to the yield stress. The ratio characterises the beginning of the second damage stage of crack propagation for the ferrite-pearlite steels. The authors have advanced the dependences of maximum symmetrical load stresses versus the duration of fatigue failure of welded joints for different types of shipbuilding steels.

Key words: fatigue life, structural damages, macrocrack, microcrack, resource, welded joint, failure stages.

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