Subsurface Stress Fields in Face-Centered-Cubic Single-Crystal Anisotropic ContactsSource: Journal of Engineering for Gas Turbines and Power:;2006:;volume( 128 ):;issue: 004::page 879DOI: 10.1115/1.2180276Publisher: The American Society of Mechanical Engineers (ASME)
Abstract: Single-crystal superalloy turbine blades used in high-pressure turbomachinery are subject to conditions of high temperature, triaxial steady and alternating stresses, fretting stresses in the blade attachment and damper contact locations, and exposure to high-pressure hydrogen. The blades are also subjected to extreme variations in temperature during start-up and shutdown transients. The most prevalent high-cycle fatigue (HCF) failure modes observed in these blades during operation include crystallographic crack initiation/propagation on octahedral planes and noncrystallographic initiation with crystallographic growth. Numerous cases of crack initiation and crack propagation at the blade leading edge tip, blade attachment regions, and damper contact locations have been documented. Understanding crack initiation/propagation under mixed-mode loading conditions is critical for establishing a systematic procedure for evaluating HCF life of single-crystal turbine blades. This paper presents analytical and numerical techniques for evaluating two- and three-dimensional (3D) subsurface stress fields in anisotropic contacts. The subsurface stress results are required for evaluating contact fatigue life at damper contacts and dovetail attachment regions in single-crystal nickel-base superalloy turbine blades. An analytical procedure is presented for evaluating the subsurface stresses in the elastic half-space, based on the adaptation of a stress function method outlined by Lekhnitskii (1963, Theory of Elasticity of an Anisotropic Elastic Body, Holden-Day, Inc., San Francisco, pp. 1–40). Numerical results are presented for cylindrical and spherical anisotropic contacts, using finite element analysis. Effects of crystal orientation on stress response and fatigue life are examined. Obtaining accurate subsurface stress results for anisotropic single-crystal contact problems require extremely refined 3D finite element grids, especially in the edge of contact region. Obtaining resolved shear stresses on the principal slip planes also involves considerable postprocessing work. For these reasons, it is very advantageous to develop analytical solution schemes for subsurface stresses, whenever possible.
keyword(s): Crystals , Stress , Finite element analysis , Elastic half space , Crystal structure , Blades , Shear (Mechanics) , Fatigue life , Fatigue AND Deformation ,
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contributor author | Nagaraj K. Arakere | |
contributor author | Gregory R. Swanson | |
contributor author | Gregory Duke | |
contributor author | Gilda Ham-Battista | |
contributor author | Erik Knudsen | |
date accessioned | 2017-05-09T00:19:46Z | |
date available | 2017-05-09T00:19:46Z | |
date copyright | October, 2006 | |
date issued | 2006 | |
identifier issn | 1528-8919 | |
identifier other | JETPEZ-26926#879_1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl/handle/yetl/133638 | |
description abstract | Single-crystal superalloy turbine blades used in high-pressure turbomachinery are subject to conditions of high temperature, triaxial steady and alternating stresses, fretting stresses in the blade attachment and damper contact locations, and exposure to high-pressure hydrogen. The blades are also subjected to extreme variations in temperature during start-up and shutdown transients. The most prevalent high-cycle fatigue (HCF) failure modes observed in these blades during operation include crystallographic crack initiation/propagation on octahedral planes and noncrystallographic initiation with crystallographic growth. Numerous cases of crack initiation and crack propagation at the blade leading edge tip, blade attachment regions, and damper contact locations have been documented. Understanding crack initiation/propagation under mixed-mode loading conditions is critical for establishing a systematic procedure for evaluating HCF life of single-crystal turbine blades. This paper presents analytical and numerical techniques for evaluating two- and three-dimensional (3D) subsurface stress fields in anisotropic contacts. The subsurface stress results are required for evaluating contact fatigue life at damper contacts and dovetail attachment regions in single-crystal nickel-base superalloy turbine blades. An analytical procedure is presented for evaluating the subsurface stresses in the elastic half-space, based on the adaptation of a stress function method outlined by Lekhnitskii (1963, Theory of Elasticity of an Anisotropic Elastic Body, Holden-Day, Inc., San Francisco, pp. 1–40). Numerical results are presented for cylindrical and spherical anisotropic contacts, using finite element analysis. Effects of crystal orientation on stress response and fatigue life are examined. Obtaining accurate subsurface stress results for anisotropic single-crystal contact problems require extremely refined 3D finite element grids, especially in the edge of contact region. Obtaining resolved shear stresses on the principal slip planes also involves considerable postprocessing work. For these reasons, it is very advantageous to develop analytical solution schemes for subsurface stresses, whenever possible. | |
publisher | The American Society of Mechanical Engineers (ASME) | |
title | Subsurface Stress Fields in Face-Centered-Cubic Single-Crystal Anisotropic Contacts | |
type | Journal Paper | |
journal volume | 128 | |
journal issue | 4 | |
journal title | Journal of Engineering for Gas Turbines and Power | |
identifier doi | 10.1115/1.2180276 | |
journal fristpage | 879 | |
journal lastpage | 888 | |
identifier eissn | 0742-4795 | |
keywords | Crystals | |
keywords | Stress | |
keywords | Finite element analysis | |
keywords | Elastic half space | |
keywords | Crystal structure | |
keywords | Blades | |
keywords | Shear (Mechanics) | |
keywords | Fatigue life | |
keywords | Fatigue AND Deformation | |
tree | Journal of Engineering for Gas Turbines and Power:;2006:;volume( 128 ):;issue: 004 | |
contenttype | Fulltext |