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ASTM Selected Technical Papers
Composite Materials: Fatigue and Fracture (Third Volume)
By
TK O'Brien
TK O'Brien
1
U.S. Army Aerostructures Directorate (AVSCOM), NASA Langley Research Center
,
Hampton, Virginia
;
symposium chairman and editor
.
Search for other works by this author on:
ISBN-10:
0-8031-1419-2
ISBN:
978-0-8031-1419-7
No. of Pages:
838
Publisher:
ASTM International
Publication date:
1991

A test fixture for testing a thick split cantilever beam for scissoring delamination (Mode III) fracture toughness was developed. A three-dimensional finite element analysis was conducted on the test specimen to determine the strain energy release rate, G, distribution along the delamination front. The virtual crack closure technique was used to calculate the G components resulting from interlaminar tension, GI, interlaminar sliding shear, GII, and interlaminar tearing shear, GIII. The finite element analysis showed that at the delamination front no GI component existed, but a GII component was present in addition to a GIII component. Furthermore, near the free edges, the GII component was significantly higher than the GIII component. The GII/GIII ratio was found to increase with delamination length but was insensitive to the beam depth. The presence of GII at the delamination front was verified experimentally by examination of the failure surfaces. At the center of the beam, where the failure was in Mode III, there was significant fiber bridging. However, at the edges of the beam where the failure was in Mode II, there was no fiber bridging and Mode II shear hackles were observed. Therefore, it was concluded that the split cantilever beam configuration does not represent a pure Mode III test. The experimental work showed that the Mode II fracture toughness, GIIc, must be less than the Mode III fracture toughness, GIIIc. Therefore, a conservative approach to characterizing Mode III delamination is to equate GIIIc to GIIc.

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,
J. M.
,
Browning
,
C. E.
, and
Hoogsteden
,
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, “
A Double Cantilever Beam Test for Characterizing Mode I Delamination of Composite Materials
,”
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1
,
10
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2.
Wilkins
,
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,
Eisenmann
,
J. R.
,
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,
R. A.
,
Margolis
,
W. S.
, and
Benson
,
R. A.
, “
Characterizing Delamination Growth in Graphite-Epoxy
,”
Damage in Composite Materisl
, ASTM STP 775,
Reifsnider
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, Ed.,
American Society for Testing and Materials
,
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,
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3.
Russell
,
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, “
Factors Affecting the Opening Mode Delamination of Graphite/Epoxy Laminates
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4.
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and
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,”
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,
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5.
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,
P. E.
,
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,
L. B.
,
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,
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, and
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,
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,”
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, Vol.
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,
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Martin
,
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,
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,
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8.
Russell
,
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and
Street
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Factors Affecting the Interlaminar Fracture Energy of Graphite/Epoxy Laminates
,”
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9.
Russell
,
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, “
On the Measurement of Mode II Interlaminar Fracture Energies
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12
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.
10.
Murri
,
G. B.
and
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,
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Interlaminar GIIc Evaluation of Toughened Resin Composites Using the End-notched Flexure Test
,” AIAA-85-0647,
Proceedings
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,
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11.
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,
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and
Kochhar
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Finite Element Analysis of End Notched Flexure Specimens
,”
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, No.
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, Summer
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, pp. 54–57.
12.
Salpekar
,
S. A.
,
Raju
,
I. S.
, and
O'Brien
,
T. K.
, “
Strain Energy Release Rate Analysis of the End-Notched Flexure Specimen Using the Finite-Element Method
,”
Journal of Composites Technology and Research
 0884-6804, Vol.
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13.
Carlsson
,
L. A.
,
Gillespie
,
J. W.
, and
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R. B.
, “
On the Analysis and Design of the End Notched Flexure (ENF) Specimen for Mode II Testing
,”
Journal of Composite Materials
, Vol.
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,
11
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, pp. 594–604.
14.
Carlsson
,
L. A.
,
Gillespie
,
J. W.
, and
Tretheway
,
B. R.
, “
Mode II Interlaminar Fracture of Graphite/Epoxy and Graphite/PEEK
,”
Journal of Reinforced Plastics and Composites
, Vol.
5
,
07
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, pp. 170–187.
15.
O'Brien
,
T. K.
,
Murri
,
G. B.
, and
Salpekar
,
S. A.
, “
Interlaminar Shear Fracture Toughness and Fatigue Thresholds for Composite Materials
,”
Composite Materials: Fatigue and Fracture, Second Volume
, ASTM STP 1012,
Lagace
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, Ed.,
American Society for Testing and Materials
,
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,
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, pp. 222–250.
16.
O'Brien
,
T. K.
, “
Mixed-Mode Strain-Energy-Release-Rate Effects on Edge Delamination of Composites
,”
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, ASTM STP 836,
American Society for Testing and Materials
,
Philadelphia
,
1984
, pp. 125–142.
17.
Whitcomb
,
J. D.
, “
Instability-Related Delamination Growth of Embedded and Edge Delaminations
,” Ph.D. thesis,
Virginia Polytechnic Institute and State University
, Blockburg, VA,
05
1988
.
18.
Salpekar
,
S. A.
,
Raju
,
I. S.
, and
O'Brien
T. K.
, “
Strain Energy Release Rate Analysis of Delamination in a Tapered Laminate Subjected to Tension Load
,”
Proceedings
, American Society for Composites, Third Technical Conference,
Seattle
, 25–29 Sept. 1988, pp. 642–654.
19.
O'Brien
,
T. K.
and
Raju
,
I. S.
, “
Strain-Energy-Release Rate Analysis of Delamination Around an Open Hole in Composite Laminates
,” AIAA-84-0961,
Proceedings
, Twenty-Fifth AIAA/ASME/ASCE/AHS Conference on Structures,
Palm Springs, CA
, 17–18 May 1984, pp. 526–536.
20.
Chaouk
,
H.
, “
Edge Delamination Behaviour in Advanced Composite Structures Under Compression Loading
,” Ph.D. thesis,
The University of Sydney
, Australia,
02
1988
.
21.
Donaldson
,
S. L.
, “
Mode III Interlaminar Fracture Characterization of Composite Materials
,”
Composites Science and Technology
, Vol.
32
, No.
3
,
1988
, pp. 225–249.
22.
Donaldson
,
S. L.
and
Mall
,
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, “
Delamination Growth in Graphite/Epoxy Composites Subjected to Mode III Loading
,”
Journal of Reinforced Plastics
, Vol.
8
,
01
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, pp. 91–103.
23.
Chai
,
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, “
Shear Fracture
,”
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, Vol.
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,
1988
, pp. 137–159.
24.
Becht
,
G.
and
Gillespie
,
J. W.
, Jr.
, “
Design and Analysis of the Crack Rail Shear Specimen for Mode III Interlaminar Fracture
,”
Composites Science and Technology
, Vol.
31
,
1988
, pp. 143–157.
25.
Gillespie
,
J. W.
, Jr.
and
Becht
,
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, “
An Investigation of Interlaminar Fracture of Composite Materials Under Mode III Loading
,” presented at Composites '88,
Boucherville, Quebec, Canada
,
11
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27.
Whitney
,
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,
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,
C. E.
, and
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, “
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,”
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, ASTM STP 546,
American Society for Testing and Materials
,
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,
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, pp. 30–45.
28.
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,
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, and
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A Virtual Crack-Closure Technique for Calculating Stress Intensity Factors for Cracked Three Dimensional Bodies
,”
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, Vol.
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, pp. R43–R50.
30.
Kanninen
,
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, “
An Augmented Double Cantilever Beam Model for Studying Crack Propagation and Arrest
,”
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, Vol.
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, No.
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,
03
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, pp. 83–91.
31.
Zweben
,
C.
,
Smith
,
W. S.
, and
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,
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, “
Test Methods for Fiber Tensile Strength, Composite Flexural Modulus, and Properties of Fabric-Reinforced Laminates
,”
Composite Materials: Testing and Design (Fifth Conference)
, ASTM STP 674,
Tsai
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, Ed.,
American Society for Testing and Materials
,
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,
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, pp. 228–262.
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