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Correlation between crack length and load drop for low-cycle fatigue crack growth in Ti-6242

Rebecka Brommesson (Institutionen för tillämpad mekanik, Material- och beräkningsmekanik) ; Magnus Ekh (Institutionen för tillämpad mekanik, Material- och beräkningsmekanik) ; Magnus Hörnqvist (Institutionen för teknisk fysik, Materialens mikrostruktur )
International Journal of Fatigue (0142-1123). Vol. 81 (2015), p. 1-9.
[Artikel, refereegranskad vetenskaplig]

Abstract For low-cycle fatigue tests with smooth bars the number of cycles to initiation is commonly defined from a measured relative drop in maximum load. This criterion cannot be directly related to the crack length, which is the actual measure of interest. In order to establish a relation between load drop and crack length for the high strength titanium alloy Ti-6242, this investigation compares data from controlled low-cycle fatigue crack growth tests and numerical simulations of these tests. To achieve sufficient accuracy in this relation, focus is given to modelling of mean stress relaxation. Three constitutive models, the Chaboche, the Ohno-Wang and the Chaboche with threshold, are evaluated with respect to experiments. Furthermore, a straightforward method with cycle-scaling of the material parameters are used to efficiently reduce calculation cost. It is shown that it is possible to determine the relationship between load drop and crack length from numerical simulations, provided that care is taken to relevant aspects of the materials stress-strain response. These results are also used to numerically evaluate the effect on load drop of the extensometer position relative to the crack.

Nyckelord: Cycle-scaling , Cyclic plasticity models , Finite element method , Low-cycle fatigue crack growth , Mean stress relaxation



Denna post skapades 2015-08-20. Senast ändrad 2015-11-23.
CPL Pubid: 220905

 

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Institutioner (Chalmers)

Institutionen för tillämpad mekanik, Material- och beräkningsmekanik
Institutionen för teknisk fysik, Materialens mikrostruktur (2012-2015)

Ämnesområden

Teknisk mekanik

Chalmers infrastruktur