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Transferability of fatigue data

Vormwald, Michael and Hertel, Olaf and Kaffenberger, Matthias (2012):
Transferability of fatigue data.
In: Proc. XIII Portuguese Conf. on Fracture, Coimbra, [Conference or Workshop Item]

Abstract

The initiation of a fatigue crack is a much localised physical phenomenon. In most actual codes of practise local stresses and strains are correlated to total failure life including the crack growth stage. Transferability is therefore limited and can only be established by a rigorous separation in initiation and propagation stages, the latter to be treated by means of fracture mechanics. Even for cases with assumed minor importance of the crack propagation stage – the subject addressed in this paper – it is essential to consider the size effect for improving data transferability. There are two classical views on size effect phenomena: a geometrical and a statistical. The weakest link theory provides a generally accepted tool to take the statistical size effect into account. Examples for welded and non-welded structures show that acceptable strength assessments are achieved applying this tool. However, the somehow diffusely defined geometrical size effect must be called additionally. The geometrical size effect is here interpreted in term of fracture mechanics based arguments for non-welded structures. For welded joints an application of Neuber’s micro structural support theory is presented, instead. Both methods give reasonable accuracies in fatigue strength assessments. However, an explanation of fatigue of welds based on fracture mechanics arguments remains to be done starting from micro structural issues.

Item Type: Conference or Workshop Item
Erschienen: 2012
Creators: Vormwald, Michael and Hertel, Olaf and Kaffenberger, Matthias
Title: Transferability of fatigue data
Language: English
Abstract:

The initiation of a fatigue crack is a much localised physical phenomenon. In most actual codes of practise local stresses and strains are correlated to total failure life including the crack growth stage. Transferability is therefore limited and can only be established by a rigorous separation in initiation and propagation stages, the latter to be treated by means of fracture mechanics. Even for cases with assumed minor importance of the crack propagation stage – the subject addressed in this paper – it is essential to consider the size effect for improving data transferability. There are two classical views on size effect phenomena: a geometrical and a statistical. The weakest link theory provides a generally accepted tool to take the statistical size effect into account. Examples for welded and non-welded structures show that acceptable strength assessments are achieved applying this tool. However, the somehow diffusely defined geometrical size effect must be called additionally. The geometrical size effect is here interpreted in term of fracture mechanics based arguments for non-welded structures. For welded joints an application of Neuber’s micro structural support theory is presented, instead. Both methods give reasonable accuracies in fatigue strength assessments. However, an explanation of fatigue of welds based on fracture mechanics arguments remains to be done starting from micro structural issues.

Title of Book: Proc. XIII Portuguese Conf. on Fracture
Volume: ISBN 978-989-97701-0-2
Place of Publication: Coimbra
Uncontrolled Keywords: Fatigue, size effect, transferability
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics > Fachgebiet Werkstoffmechanik
13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics
13 Department of Civil and Environmental Engineering Sciences
Date Deposited: 30 Jan 2015 13:36
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