Modelling of Stresses in Welded Joints Under Consideration of Plastic Strains in Fatigue Life Calculations*

Łukasz Blacha; Aleksander Karolczuk; Tadeusz Łagoda

doi:10.3139/120.110234

Article

Modelling of Stresses in Welded Joints Under Consideration of Plastic Strains in Fatigue Life Calculations*

Łukasz Blacha , Aleksander Karolczuk and Tadeusz Łagoda

Published/Copyright: May 28, 2013

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From the journal Materials Testing Volume 53 Issue 6

Abstract

Welded joints submitted to variable loadings are, by their nature, experiencing a stress concentration resulting from the presence of a complex notch effect relating to geometrical and structural features of the joint. In the finite element method, modelling of the weld toe as a sharp notch reveals a non-linear relation of stresses dependent on the mesh density. In this paper, an approach for determination of the notch radius in a welded part was proposed, based on the application of finite element calculations with a non-linear elastic-plastic body model under employment of the linear hardening rule. The derived stresses are used in calculations of fatigue life, carried out according to algorithms provided for structural elements without the presence of welds.

Kurzfassung

Schweißverbindungen, die variablen Beanspruchungen unterworfen sind, erfahren naturgemäß eine Spannungskonzentration, die aus der Anwesenheit von komplexen Kerbwirkungen infolge der geometrischen und strukturellen Eigenschaften der Verbindung resultieren. In der Finite-Elemente-Modellierung ergibt die Modellierung der Nahtwurzel als scharfe Kerbe eine nicht- lineare Beziehung der Spannungen, abhängig von der Netzdichte. Im vorliegenden Beitrag wird ein Ansatz für die Bestimmung des Kerbradius in einem geschweißten Teil propagiert, der auf der Anwendung von Finite-Elemente-Berechnungen mit einem nicht-linearen elastisch-plastischen Volumenmodell unter Einbeziehung des linearen Verfestigungsgesetzes basiert. Die bestimmten Spannungen werden in Berechnungen der Lebensdauer verwendet, die wie die Algorithmen ausgeführt werden, wie sie für Strukturelemente ohne Schweißverbindungen gelten.

Extended version of the contribution for the Symposium on Fatigue Failure and Fracture Mechanics

MSc. Lukasz Blacha, born 1984, is a doctoral student at the Department of Mechanics and Machine Design at the Opole University of Technology. He graduated in Mechanical Engineering, and gained his industrial experience during the served internship as a FEA engineer at DELPHI Technical Center in Kraków, Poland.

Prof. Aleksander Karolczuk, born 1974, is currently an Associated Professor at the Opole University of Technology in Poland. He is the coauthor of one book (published by VDI Verlag 2005), and numerous papers and conference presentations devoted to various aspects of fatigue of materials. His works concern especially multiaxial fatigue failure criteria based on the critical plane approach, non-local methods and models of material hardening.

Prof. Tadeusz Łagoda, born 1965, is Head of Department of Mechanics and Machine Design at the Opole University of Technology. His works concern especially multiaxial random fatigue and criteria based on the critical plane approach and fatigue of welding joint. He is author and coauthor of more then 250 papers and monographs. The last one is: T. Agoda: Lifetime Estimation of Welded Joints, Springer Verlag 2008.

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Published Online: 2013-05-28

Published in Print: 2011-06-01

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https://doi.org/10.3139/120.110234