|
|||||
 |
|
|
|
|
|
Numerical exploration
of the Dang Van high cycle fatigue criterion: application to
gradient effects
Felix Hofmann, Gratiela Bertolino, Andrei Constantinescu and Mohamed Ferjani |
|
Vol. 4 (2009), No. 2, 293–308
|
Abstract |
|
The objective of this paper is to show that a number of key features of the Dang Van high cycle fatigue criterion can be observed using simple polycrystalline computational models. This paper presents a series of numerical computations for an inclusion consisting of 156 grains embedded in a homogeneous matrix. The grains are modeled using a polycrystalline single slip elastoplastic model, whilst the matrix is considered as elastic. As expected the numerical simulations confirm the theoretical prediction on which the Dang Van fatigue criterion is based, that if a large enough number of grains is considered under uniform loading, a grain with the least favourable lattice orientation will always be present. This grain will constitute the weakest link in the assembly and thus its fatigue life largely determines the fatigue life of the bulk material. Next the question of stress-gradients in the high cycle fatigue regime is addressed. An example of stress gradients appears around notches as they create stress concentrations in structures. It is a well known problem that fatigue criteria have to be locally arranged using stress-factors or critical distances in order to give satisfactory predictions. The work presented here shows that an analysis of the problem at the grain scale explains the apparent discrepancy when using classical fatigue criteria. The discussion is based on a numerical model of single slip crystal plasticity and the Dang Van fatigue criterion. |
Keywords
high cycle fatigue, fatigue criterion, polycrystalline
plasticity, stress gradient, notch
|
Milestones
Received: 14 December 2007
Revised: 14 June 2008
Accepted: 17 July 2008
Published: 12 April 2009
|
Authors |
| Felix Hofmann | |
| Department of Engineering
Science Oxford University Parks Road Oxford, OX1 3PJ United Kingdom |
|
| Gratiela Bertolino | |
| Centro Atomico Bariloche 8400 San Carlos de Bariloche Río Negro Argentina |
|
| Andrei Constantinescu | |
| Laboratoire de Mécanique des Solides
- CNRS École Polytechnique 91128 Palaiseau France |
|
| Mohamed Ferjani | |
| Institut Français du Pétrole 1-4 rue Bois-Préau 92852 Rueil-Malmaison France |
|
|
