Crack opening displacements during fatigue crack growth in Ti–SiC fibre metal matrix composites by X-ray tomography

Abstract

High spatial resolution X-ray microtomography has been used to map the variation of crack opening displacement (COD) across matrix cracks in unidirectional Ti–6Al–4V/SCS-6 SiC fibre composites. These show the crack front to bow out between fibres as the crack emerges from a ply and to advance preferentially towards the fibres when located between plies. Quantitative image analysis of 3D volume reconstructions has enabled the COD to be measured at K_min, K_mid and K_max. Hysteresis in crack opening was observed during the fatigue cycle (loads applied statically). Very little variation in COD has been observed parallel to the crack front irrespective of proximity to the bridging fibres. The changes in COD relative to the initial residual opening at K_min are not inconsistent with being proportional to the square root of the distance from the crack tip. Considerable crack blunting was observed during an overload leading to a significant residual crack opening upon unloading.

Keywords

CRACK-TIP SHIELDING TITANIUM MATRIX COMPOSITE CRACK BRIDGING SYNCHROTRON X-RAY INTERFACIAL SLIDING INTERFACIAL WEAR

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References

Hooker

J. A.

and Doorbar

P. J.

: Mater. Set TechnoL, 2000, 16, 725–731.

Harris

: ‘Engineering composite materials’, 2nd edn; 1999, London, Institute of Metals.

Harris

, Beaumont

W. R.

and Moncunil

: J. Mater. Sci., 1971, 6, (3), 238.

Davidson

D. L.

: Metall. Trans. A, 1992, 23A, 865–879.

Walls

D. P.

and Zok

F. W.

: Acta Metall Mater., 1994, 42, (8), 2675–81.

Warrier

S. G.

, Majumdar

B. S.

and Miracle

D. B.

: Acta Mater., 1997, 45, 4969–80.

Hutchinson

J. W.

and Jensen

H. M.

: Mech. Mater., 1990, 9, 139–163.

Chan

K. S.

: Acta Metall. Mater., 1993, 41, 761–768.

McCartney

: Proc. Roy. Soc. Lond. A, 1987, 409A, 329–350.

10.

Marshall

D. B.

, Cox

B. N.

and Evans

A. G.

: Acta Metall., 1985, 33, 2013–2021.

11.

Cox

B. N.

and Lo

C. S.

: Acta Metall. Mater., 1992, 40, (7), 1487–1496.

12.

Connell

S. J.

and Zok

F. W.

: Acta Metall. Mater., 1997, 45, (12), 5203–211.

13.

Tanaka

, Kagawa

, Liu

Y.-F.

and Masuda

: Mater. Set Eng. A, 2001, 314A, 110–117.

14.

Sinclair

, Preuss

and Withers

P. J.

: Mater. Set TechnoL, 2005, 21, 27–34.

15.

Sinclair

, Preuss

, Maire

, Buffiere

J.-Y.

, Bowen

and Withers

P. J.

: Acta Mater., 2004, 52, 1423–1438.

16.

Hutson

, John

and Jira

J. R.

: Script. Mater., 1999, 40, 529–535.

17.

Buchanan

D. J.

, John

and Johnson

D. A.

: Int. J. Fract., 1997, 87, 101–17.

18.

Liu

and Bowen

: Metall. Mater. Trans. A, 2003, 34A, 1193–1202.

19.

Rauchs

, Thomason

P. F.

and Withers

P. J.

: Int. J. Fract., 2004, 125, 281–305.

20.

Larsen

J. M.

, Jira

J. R.

, John

and Ashbaugh

N. E.

: in ‘Life prediction methodology for titanium matrix composites’, (ed. Johnson

W. S.

et al), ASTM STP 1253, 114-136; 1996, Philadelphia, PA, ASTM.

21.

John

, Jira

J. R.

and Larsen

J. M.

: in ‘Composite materials: fatigue and fracture’, (ed. Bucinell

R. B.

), ASTM STP 1330, 122-144; 1998, Philadelphia, PA, ASTM.

22.

Breunig

T. M.

, Stock

S. R.

, Antolovich

S. D.

, Kinney

J. H.

, Massey

W. N.

and Nichols

M. C.

: Proc. 22nd Int. Fracture Mechanics Symp., (ed. Ernst

H. A.

et al), ASTM STP1131, 209-214; 1992, Philadelphia, PA, ASTM.

23.

Guvenilir

, Breunig

T. M.

, Kinney

J. H.

and Stock

S. R.

: Acta Mater., 1999, 45, 1977–87.

24.

McDonald

S. A.

, Preuss

, Maire

, Buffiere

J.-Y.

, Mummery

P. M.

and Withers

P. J.

: J. Micros., 2003, 209, 102–112.

25.

Budiansky

and Amaziago

J. C.

: J. Mech. Phys. Solid:, 1989, 37, 93.