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Article
Publication date: 8 March 2011

Miguel Morales, Carlos Correa, Juan Antonio Porro, Carlos Molpeceres and José Luis Ocaña

Laser shock peening (LSP) is mainly a mechanical process, but in some cases, it is performed without a protective coating and thermal effects are present near the surface. The…

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Abstract

Purpose

Laser shock peening (LSP) is mainly a mechanical process, but in some cases, it is performed without a protective coating and thermal effects are present near the surface. The numerical study of thermo‐mechanical effects and process parameter influence in realistic conditions can be used to better understand the process.

Design/methodology/approach

A physically comprehensive numerical model (SHOCKLAS) has been developed to systematically study LSP processes with or without coatings starting from laser‐plasma interaction and coupled thermo‐mechanical target behavior. Several typical results of the developed SHOCKLAS numerical system are presented. In particular, the application of the model to the realistic simulation (full 3D dependence, non‐linear material behavior, thermal and mechanical effects, treatment over extended surfaces) of LSP treatments in the experimental conditions of the irradiation facility used by the authors is presented.

Findings

Target clamping has some influence on the results and needs to be properly simulated. An increase in laser spot radius and an increase in pressure produces an increase of the maximum compressive residual stress and also the depth of the compressive residual stress region. By increasing the pulse overlapping density, no major improvements are obtained if the pressure is high enough. The relative influence of thermal/mechanical effects shows that each effect has a different temporal scale and thermal effects are limited to a small region near the surface and compressive residual stresses very close to the surface level can be induced even without any protective coating through the application of adjacent pulses.

Originality/value

The paper presents numerical thermo‐mechanical study for LSP treatments without coating and a study of the influence of several process parameters on residual stress distribution with consideration of pulse overlapping.

Details

International Journal of Structural Integrity, vol. 2 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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Abstract

Details

International Journal of Structural Integrity, vol. 2 no. 1
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 24 August 2012

Gulshan Singh, Juan Ocampo, Harry Millwater and Allan Clauer

The purpose of this paper is to develop an approach to optimize the cycles‐to‐failure of a peened component with respect to laser peening (LP) variables: pressure magnitude…

192

Abstract

Purpose

The purpose of this paper is to develop an approach to optimize the cycles‐to‐failure of a peened component with respect to laser peening (LP) variables: pressure magnitude, mid‐span, and spot size when the component is subject to a variable amplitude loading.

Design/methodology/approach

To optimally design an LP process, an experimentally validated 3D finite element simulation of the LP process, a cycles‐to‐failure estimation capability incorporating residual stress, and a particle swarm optimization strategy were developed and employed to maximize the cycles‐to‐failure of a component of a titanium turbine disk.

Findings

The most critical finding of this research is that a minor difference in the residual stress profile can lead to a large difference in the cycles‐to‐failure. This finding implies that selecting the optimization objective to be the cycles‐to‐failure is a better option as compared to the residual stress profile.

Research limitations/implications

The LP‐induced residual stresses are assumed static and do not change as number of load cycles increase.

Originality/value

The paper develops a framework that relates the LP variables and the cycles‐to‐failure of a peened component. A modified particle swarm optimization approach is developed to optimize the fatigue life of a turbine disk.

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