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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
.
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ISBN-10:
0-8031-1419-2
ISBN:
978-0-8031-1419-7
No. of Pages:
838
Publisher:
ASTM International
Publication date:
1991

An analytical and empirical study was conducted to investigate delamination behavior in composite structures.

The objective of the analysis was to predict the threshold stress for the initiation of delamination growth in compressively loaded composite laminates. MSC/NASTRAN geometrically nonlinear finite element analysis and a virtual crack opening technique were used to compute strain energy release rate distributions around circular delaminations. The distributions were computed for various compressive stress levels and the threshold stress for delamination growth was then determined by applying the strain energy release rates in a mixed-mode fracture criterion.

A number of static compression tests were conducted on specimens made from AS4/3501-5A graphite fabric-reinforced epoxy. The specimens contained circular delaminations of various sizes. The delaminations had been created by implanting Teflon inclusions in the prepreg layup.

Computed predictions of the delamination growth threshold stresses were significantly in error relative to the test data. The analysis did, however, concur with observed trends and provided qualitative insight into the process of quasi-static delamination growth.

1.
Kan
,
H. P.
,
Deo
,
R. B.
,
Shah
,
C.
, and
Kinslow
,
R.
, “
Resistance Curve Approach to Predicting Residual Strength of Composites
,” Report No. AFOSR-TR-87-0062,
Air Force Office of Scientific Research
, Bolling Air Force Base, DC,
09
1986
.
2.
Webster
,
J. D.
, “
Flaw Criticality of Circular Disbond Defects in Compressive Laminates
,” Report No. CCM-81-03,
Center for Composite Materials, University of Delaware
, Newark, DE,
06
1981
.
3.
Wang
,
J. T.
and
Connolly
,
J. J.
, “
A Simple Analysis Technique to Evaluate Delaminated Composite Laminate Under Compressive Load
,”
Proceedings
, Twentieth International SAMPE Technical Conference,
Society for the Advancement of Material and Process Engineering
,
09
1988
, pp. 505–516.
4.
Ashizawa
,
M.
, “
Fast Interlaminar Fracture of a Compressively Loaded Composite Containing a Defect
,”
Proceedings
, Fifth DoD/NASA Conference on Fibrous Composites in Structural Design, Report No. NADC-81096-60,
Naval Air Development Center
,
Warminster, PA
,
01
1981
, pp. 269–291.
5.
Chai
,
H.
and
Babcock
,
C. D.
, “
Two-Dimensional Modelling of Compressive Failure in Delaminated Laminates
,”
Journal of Composite Materials
, Vol.
19
,
01
1985
, pp. 67–98.
6.
Bottega
,
W. J.
and
Maewal
,
A.
, “
Delamination Buckling and Growth in Laminates
,”
Journal of Applied Mechanics
 0021-8936, Vol.
50
,
03
1983
, pp. 184–189.
7.
Whitcomb
,
J. D.
, “
Finite Element Analysis of Instability Related Delamination Growth
,”
Journal of Composite Materials
, Vol.
15
,
09
1981
, pp. 403–426.
8.
Whitcomb
,
J. D.
, “
Strain Energy Release Rate Analysis of Cyclic Delamination Growth in Compressively Loaded Laminates
,”
Effects of Defects in Composite Materials
, ASTM STP 836,
American Society for Testing and Materials
,
Philadelphia
,
1984
, pp. 175–193.
9.
Whitcomb
,
J. D.
, “
Mechanics of Instability-Related Delamination Growth
,” NASA Technical Memorandum 100622,
National Aeronautics and Space Administration, NASA Langley Research Center
,
Hampton, VA
,
05
1988
.
10.
Whitcomb
,
J. D.
, “
Three-Dimensional Analysis of a Postbuckled Embedded Delamination
,”
Journal of Composite Materials
, Vol.
23
,
09
1989
, pp. 862–889.
11.
MSC/NASTRAN Application Manual
, Vol
1
.,
Joseph
J.
, Ed.,
The MacNeal-Schwendler Corporation
,
Los Angeles, CA
,
06
1983
.
12.
Johnson
,
W. S.
and
Mangalgiri
,
P. D.
, “
Influence of the Resin on Interlaminar Mixed-Mode Fracture
,”
Toughened Composities
, ASTM STP 937,
Johnston
N. J.
, Ed.,
American Society for Testing and Materials
,
Philadelphia
,
1987
, pp. 295–315.
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