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Research Papers

Finite Element Modeling of Shot Peening Residual Stress Relaxation in Turbine Disk Assemblies

[+] Author and Article Information
S. A. Meguid

Professor
Fellow ASME
Mechanics and Aerospace Design Laboratory,
Mechanical and Industrial Engineering,
University of Toronto,
5 King's College Road,
Toronto, ON M5S 3G8, Canada
e-mail: meguid@mie.utoronto.ca

Luke A. Maricic

Mechanics and Aerospace Design Laboratory,
Mechanical and Industrial Engineering,
University of Toronto,
5 King's College Road,
Toronto, ON M5S 3G8, Canada

1Corresponding author.

Contributed by the Materials Division of ASME for publication in the JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY. Manuscript received February 16, 2014; final manuscript received March 5, 2015; published online March 30, 2015. Assoc. Editor: Ashraf Bastawros.

J. Eng. Mater. Technol 137(3), 031003 (Jul 01, 2015) (8 pages) Paper No: MATS-14-1037; doi: 10.1115/1.4030066 History: Received February 16, 2014; Revised March 05, 2015; Online March 30, 2015

Surface enhancement techniques such as shot peening are extensively used to increase the fatigue life of components in gas turbine engines. Due to the combined thermomechanical nature of the loading encountered within an engine, aeroengine designers have avoided incorporating the beneficial effects in their analysis. This can lead to overdesign and early retirement of critical engine components. A finite element modeling procedure is introduced that incorporates the shot peening residual stresses on a fir-tree turbine disk assembly. Unlike traditional equivalent loading approaches, the method models the actual impact of shots on the assembly and is the first time this approach is used to introduce peening residual stresses in turbine disks. In addition, the stability of these residual stresses in response to cyclic thermomechanical loadings at the contact interface is also studied. The results reveal that thermomechanical overload can nearly fully relax the shot peening residual stresses within the first cycle due to the combined effects of decreased material yield strength and plastic deformation. This work will enable aeroengine designers to assess critical surface treated components for structural integrity, optimal design, and residual life.

Copyright © 2015 by ASME
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References

Figures

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Fig. 2

FE mesh at blade–disk contact interface region

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Fig. 3

True stress versus true plastic strain Inconel 718 [27]

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Fig. 4

Plastic stress–strain curves at various temperatures (Inconel 718)

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Fig. 5

Shot peening modeling procedure: (a) symmetry section and (b) process flowchart

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Fig. 6

Shot peening submodel: (a) view of staggered layers and (b) view normal to peening surface

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Fig. 7

Turbine disk assembly relaxation model

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Fig. 8

Typical triangular cyclic loading

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Fig. 9

Temperature distribution along disk radius

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Fig. 10

Residual stress profile comparison on lower root: (a) shot peening submodel and (b) full turbine disk assembly with initialized stresses

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Fig. 11

Resulting residual stress state from the various developed FE models

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Fig. 12

Locations for residual stress relaxation analysis

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Fig. 13

Residual stress relaxation for mechanical loads at 6000 rpm: (a) versus number of cycles and (b) versus depth

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Fig. 14

Residual stress relaxation for mechanical overload: (a) versus number of cycles and (b) versus depth

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Fig. 15

Residual stress relaxation for combined thermomechanical loads at 6000 rpm: (a) versus number of cycles and (b) versus depth

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Fig. 16

Residual stress relaxation for combined thermomechanical overload: (a) versus number of cycles and (b) versus depth

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Fig. 17

Residual stress profile (σxx) of disk lower root after cyclic thermomechanical overload

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Fig. 18

Evolution of equivalent plastic strain

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