Sub-surface fatigue crack tip strains in 7475-T7351 aluminium alloy measured using stroboscopic neutron diffraction

Harry Coules; Molly A Probert; Kisaburo Azuma; Christopher E Truman; Cui Seow; Thilo Pirling; Sandra Cabeza

Sub-surface fatigue crack tip strains in 7475-T7351 aluminium alloy measured using stroboscopic neutron diffraction

Harry Coules, Molly A Probert, Kisaburo Azuma, Christopher E Truman, Cui Seow, Thilo Pirling, Sandra Cabeza

Research output: Contribution to journal › Article (Academic Journal) › peer-review

Abstract

Fatigue crack growth in thick-section metals is typically controlled by an internal plane strain region where strong triaxial constraint of the crack tip occurs. However, the crack tip stress state in this region is challenging to measure. We have used neutron diffraction to study the plane strain section of fatigue crack tips in situ. A stroboscopic form of neutron diffraction using a moving frame-of-reference was developed to measure crack tip strains as a function of phase in the fatigue loading cycle without interrupting the cyclic load. Using point measurements of near-tip strain in 7475-T7351 aluminium alloy in conjunction with finite element analysis, we can estimate the extent of the crack tip plastic zone, verifying that it is small for this material and set of loading conditions.

Original language	English
Journal	Fatigue and Fracture of Engineering Materials and Structures
Volume	46
Issue number	5
Early online date	17 Feb 2023
Publication status	E-pub ahead of print - 17 Feb 2023

Keywords

Fatigue
Stress ratio
Aluminium alloy
Neutron diffraction
Stroboscopy
Finite Element Analysis

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Persistent link

Effects of load and defect history on fracture in the presence of residual and thermal stress
Coules, H. (Principal Investigator), Truman, C. E. (Co-Principal Investigator) & Probert, M. A. (Student)
1/04/17 → 1/10/21
Project: Research

Cite this

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title = "Sub-surface fatigue crack tip strains in 7475-T7351 aluminium alloy measured using stroboscopic neutron diffraction",

abstract = "Fatigue crack growth in thick-section metals is typically controlled by an internal plane strain region where strong triaxial constraint of the crack tip occurs. However, the crack tip stress state in this region is challenging to measure. We have used neutron diffraction to study the plane strain section of fatigue crack tips in situ. A stroboscopic form of neutron diffraction using a moving frame-of-reference was developed to measure crack tip strains as a function of phase in the fatigue loading cycle without interrupting the cyclic load. Using point measurements of near-tip strain in 7475-T7351 aluminium alloy in conjunction with finite element analysis, we can estimate the extent of the crack tip plastic zone, verifying that it is small for this material and set of loading conditions.",

keywords = "Fatigue, Stress ratio, Aluminium alloy, Neutron diffraction, Stroboscopy, Finite Element Analysis",

author = "Harry Coules and Probert, {Molly A} and Kisaburo Azuma and Truman, {Christopher E} and Cui Seow and Thilo Pirling and Sandra Cabeza",

year = "2023",

month = feb,

day = "17",

language = "English",

volume = "46",

journal = "Fatigue and Fracture of Engineering Materials and Structures",

issn = "1460-2695",

publisher = "Wiley-Blackwell",

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TY - JOUR

T1 - Sub-surface fatigue crack tip strains in 7475-T7351 aluminium alloy measured using stroboscopic neutron diffraction

AU - Coules, Harry

AU - Probert, Molly A

AU - Azuma, Kisaburo

AU - Truman, Christopher E

AU - Seow, Cui

AU - Pirling, Thilo

AU - Cabeza, Sandra

PY - 2023/2/17

Y1 - 2023/2/17

N2 - Fatigue crack growth in thick-section metals is typically controlled by an internal plane strain region where strong triaxial constraint of the crack tip occurs. However, the crack tip stress state in this region is challenging to measure. We have used neutron diffraction to study the plane strain section of fatigue crack tips in situ. A stroboscopic form of neutron diffraction using a moving frame-of-reference was developed to measure crack tip strains as a function of phase in the fatigue loading cycle without interrupting the cyclic load. Using point measurements of near-tip strain in 7475-T7351 aluminium alloy in conjunction with finite element analysis, we can estimate the extent of the crack tip plastic zone, verifying that it is small for this material and set of loading conditions.

AB - Fatigue crack growth in thick-section metals is typically controlled by an internal plane strain region where strong triaxial constraint of the crack tip occurs. However, the crack tip stress state in this region is challenging to measure. We have used neutron diffraction to study the plane strain section of fatigue crack tips in situ. A stroboscopic form of neutron diffraction using a moving frame-of-reference was developed to measure crack tip strains as a function of phase in the fatigue loading cycle without interrupting the cyclic load. Using point measurements of near-tip strain in 7475-T7351 aluminium alloy in conjunction with finite element analysis, we can estimate the extent of the crack tip plastic zone, verifying that it is small for this material and set of loading conditions.

KW - Fatigue

KW - Stress ratio

KW - Aluminium alloy

KW - Neutron diffraction

KW - Stroboscopy

KW - Finite Element Analysis

M3 - Article (Academic Journal)

SN - 1460-2695

VL - 46

JO - Fatigue and Fracture of Engineering Materials and Structures

JF - Fatigue and Fracture of Engineering Materials and Structures

IS - 5

ER -

Sub-surface fatigue crack tip strains in 7475-T7351 aluminium alloy measured using stroboscopic neutron diffraction

Abstract

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Effects of load and defect history on fracture in the presence of residual and thermal stress

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