Fatigue behaviour of geometric features subjected to laser shock peening: Experiments and modelling

• Published in: International journal of fatigue 2014-05, Vol.62, p.171-179
• Main Authors: Achintha, M., Nowell, D., Fufari, D., Sackett, E.E., Bache, M.R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Eigenstrain; Exact sciences and technology; Fatigue; Laser shock peening; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Residual stress
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2013.04.016

•Eigenstrain approach works well to model the fatigue of LSP treated specimens.•Interactions between the LSP process and geometric features are important.•Not all instances of LSP applications provide improvement in fatigue life.•Eigenstrain method allows modelling the effects due to balancing tensile stress. Finite element models, using the eigenstrain approach, are described that predict the residual stress fields associated with laser shock peening (LSP) applied to aerospace grade aluminium alloys. The model was used to explain the results of laboratory fatigue experiments, containing different LSP patch geometries, supplementary stress raising features and different specimen thickness. It is shown that interactions between the LSP process and geometric features are the key to understanding the subsequent fatigue strength. Particularly relevant for engineering application, is the fact that not all instances of LSP application provided an improvement in fatigue performance. Although relatively deep surface compressive residual stresses are generated which can resist fatigue crack initiation in these regions, a balancing tensile stress will always exist and its location must be carefully considered.