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ASTM Selected Technical Papers
Fractography of Modern Engineering Materials: Composites and Metals
By
JE Masters
JE Masters
1
Senior Research Engineer
,
American Cyanamid Co.
,
Stamford, CT 06904
;
symposium cochairman and coeditor
.
Search for other works by this author on:
JJ Au
JJ Au
2
Sundstrand Corp.
,
editor
Search for other works by this author on:
ISBN-10:
0-8031-0950-4
ISBN:
978-0-8031-0950-6
No. of Pages:
470
Publisher:
ASTM International
Publication date:
1987

A study of the fracture processes in T300/5208 notched laminated composites concentrated on characterizing the influences of laminate stacking sequence on the formation of notch-tip damage zones and the subsequent mode of fracture of each ply of the laminate. The results revealed that laminate notched strength varied considerably with both a specified set of ply fiber orientations as well as the order in which the specific plies were arranged in the laminate. The fractographic examinations identified differences in the laminate fracture process which are believed to be the primary contributor to the differences in notched strength. The twelve laminates exhibited varying degrees of notch sensitivity as a result of the ability of a laminate to develop “subcritical” damage in a manner that relieved the high stress concentration at the notch tip.

The percent of laminate fracture by broken fibers was in direct correlation with the laminate notched strength. Laminates which were not characterized by damage zones containing major delaminations exhibited higher percentages of failure by broken fibers and higher notched strength. Conversely, when delaminations resulted in widespread ply uncoupling, relatively few plies of a laminate failed by broken fibers producing a weaker laminate.

1.
Harris
,
C. E.
and
Morris
,
D. H.
, “
Fracture Behavior of Thick Laminated Graphite/Epoxy Composites
,” NASA Contractor Report 3784,
NASA Langley Research Center
, Hampton, VA.,
1984
.
2.
Poe
,
C. C.
 Jr.
, and
Sova
,
J. A.
, “
Fracture Toughness of Boron/Aluminum Laminates with Various Proportions of 0° and ±45° Plies
,” NASA Technical Paper 1707,
NASA Langley Research Center
,
Hampton, VA
,
1980
.
3.
Garber
,
D. P.
, “
Tensile Stress-Strain Behavior of Graphite/Epoxy Laminates
,” NASA Contractor Report 3592,
NASA Langley Research Center
,
Hampton, VA
,
1982
.
4.
Freeman
,
S. M.
, “
Characterization of Lamina and Interlaminar Damage in Graphite-Epoxy Composites by the Deply Technique
,”
Composite Materials: Testing and Design (Sixth Conference)
, ASTM STP 787,
Daniel
I. M.
, Ed.,
American Society for Testing and Materials
,
Philadelphia
,
1982
, pp. 50-62.
5.
Jamison
,
R. D.
,
Schulte
,
K.
,
Reifsnider
,
K. L.
, and
Stinchomb
,
W. W.
, “
Characterization and Analysis of Damage Mechanics in Tension-Tension Fatigue of Graphite/Epoxy Laminates
,”
Effects of Defects in Composite Materials
, ASTM STP 836,
Wilkins
D. J.
, Ed.,
American Society for Testing and Materials
,
1984
, pp. 21-55.
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