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Fatigue behaviour of geometric features subjected to laser shock peening

Fatigue behaviour of geometric features subjected to laser shock peening
Fatigue behaviour of geometric features subjected to laser shock peening
The current paper reports selected findings from a major collaborative research programme conducted in the United Kingdom into the fundamental understanding of laser shock peening, when applied to key airframe and aero-engine alloys as a means of controlling fatigue performance.

It is recognised that relatively deep compressive residual stresses are generated into the surface of a material subjected to LSP which can subsequently resist fatigue crack initiation from that surface. However, it is clear that balancing tensile stress will evolve at some location within the material in order to satisfy equilibrium and under certain circumstances this can lead to sub-surface fatigue initiation. The distribution of the RS field will be highly dependent on LSP process parameters, the structural form and the precise mode and raster pattern of pulse application.

Finite element models will be described that predict the RS fields associated with LSP applied to the aerospace grade aluminium alloys Al 2024 and Al 7010 using an eigenstrain approach. Validation of these models is provided by laboratory fatigue experiments on test coupons containing different LSP patch geometries (full width or centre constrained), supplementary stress raising features (drilled holes) and different through thickness dimensions. Particular attention is paid to modelling the application of LSP at edge locations in terms of the angle of incidence and laser pulse sequencing.

Interactions between the LSP process and geometric features was found to be key to understanding the location for fatigue crack initiation. Particularly relevant for engineering application, was the fact that not all instances of LSP application provided an improvement in cyclic fatigue life.
Achintha, Mithila
8163c322-de6d-4791-bc31-ba054cc0e07d
Nowell, David
63daaf71-e1e5-4d86-9ce9-586f82c4f12a
Furfari, Domenico
abec1cce-9b41-428d-90c2-49599d8aeabc
Sackett, Liz
befa862a-0a95-47c0-945d-f1d36e8a80c2
Bache, Martin
de5dabdc-3a43-47d2-8c6e-9ac337e9202f
Achintha, Mithila
8163c322-de6d-4791-bc31-ba054cc0e07d
Nowell, David
63daaf71-e1e5-4d86-9ce9-586f82c4f12a
Furfari, Domenico
abec1cce-9b41-428d-90c2-49599d8aeabc
Sackett, Liz
befa862a-0a95-47c0-945d-f1d36e8a80c2
Bache, Martin
de5dabdc-3a43-47d2-8c6e-9ac337e9202f

Achintha, Mithila, Nowell, David, Furfari, Domenico, Sackett, Liz and Bache, Martin (2012) Fatigue behaviour of geometric features subjected to laser shock peening. 9th Fatigue Damage of Structural Materials Conference, United States. 16 - 22 Sep 2012.

Record type: Conference or Workshop Item (Other)

Abstract

The current paper reports selected findings from a major collaborative research programme conducted in the United Kingdom into the fundamental understanding of laser shock peening, when applied to key airframe and aero-engine alloys as a means of controlling fatigue performance.

It is recognised that relatively deep compressive residual stresses are generated into the surface of a material subjected to LSP which can subsequently resist fatigue crack initiation from that surface. However, it is clear that balancing tensile stress will evolve at some location within the material in order to satisfy equilibrium and under certain circumstances this can lead to sub-surface fatigue initiation. The distribution of the RS field will be highly dependent on LSP process parameters, the structural form and the precise mode and raster pattern of pulse application.

Finite element models will be described that predict the RS fields associated with LSP applied to the aerospace grade aluminium alloys Al 2024 and Al 7010 using an eigenstrain approach. Validation of these models is provided by laboratory fatigue experiments on test coupons containing different LSP patch geometries (full width or centre constrained), supplementary stress raising features (drilled holes) and different through thickness dimensions. Particular attention is paid to modelling the application of LSP at edge locations in terms of the angle of incidence and laser pulse sequencing.

Interactions between the LSP process and geometric features was found to be key to understanding the location for fatigue crack initiation. Particularly relevant for engineering application, was the fact that not all instances of LSP application provided an improvement in cyclic fatigue life.

Full text not available from this repository.

More information

e-pub ahead of print date: 18 September 2012
Venue - Dates: 9th Fatigue Damage of Structural Materials Conference, United States, 2012-09-16 - 2012-09-22
Organisations: Engineering Science Unit

Identifiers

Local EPrints ID: 369128
URI: https://eprints.soton.ac.uk/id/eprint/369128
PURE UUID: cf57900b-472a-44f8-9c70-71988ad8b83d

Catalogue record

Date deposited: 25 Sep 2014 13:51
Last modified: 18 Jul 2017 01:40

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