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ASTM Selected Technical Papers
Instrumented Impact Testing
By
TS DeSisto
TS DeSisto
1
Army Materials and Research Center
,
Watertown, Mass. 02172
;
symposium chairman
.
Search for other works by this author on:
ISBN-10:
0-8031-0738-2
ISBN:
978-0-8031-0738-0
No. of Pages:
220
Publisher:
ASTM International
Publication date:
1974

Advanced fiber composite materials exhibit elastic properties and fracture mechanisms distinctive from metals. Consequently, the mechancis of impact resistance are also different for these materials. Carbon-epoxy and boron-epoxy composites can exhibit brittle modes of fracture. In studies to improve the impact resistance of carbon-epoxy materials, traditional impact tests provided very little understanding of the problems involved. However, instrumented Charpy-type tests provided considerable insight into the mechanisms associated with impact resistance. Load versus time response records can be partitioned into regions corresponding to events occuring sequentially in time. Energy absorbed by a composite specimen through the various fracture mechanisms is seen to be the distinguishing characteristic between composite systems. Two mechanisms to improve the carbon-epoxy system's impact resistance are shown to be the modification of the fiber-resin interfacial strength and hybridization with a second fiber of high strength and lower modulus.

1.
Toland
,
R. H.
, “
Failure Modes in Impact-Loaded Composite Materials
,” American Institute of Mining, Metallurgical and Petroleum Engineers, Spring Meeting,
Boston, Mass.
, 8–11 May 1972.
2.
Goldsmith
,
Werner
,
Impact: The Theory and Physical Behavior of Colliding Solids
,
Edward Arnold Ltd.
,
London
,
1960
.
3.
Chou
,
P. C.
, “
Introduction to Wave Propagation in Composite Materials
,”
Composite Materials Workshop
,
Tsai
,
Halpin
and
Pagano
, Eds.,
Technomic Publishing Co.
,
Stamford, Conn.
,
1968
.
4.
Mullin
,
J. V.
and
Mazzio
,
V. F.
, “
Basic Failure Mechanisms in Advanced Composites, Final Report
,” NASA Contract NASW-2093,
04
1971
.
5.
Kelly
,
A.
, “
Interface Effects and the Work of Fracture of a Fibrous Composite
,”
Proceedings of the Royal Society
, Series A. Vol.
319
,
1970
.
6.
Beaumont
,
P. W. R.
and
Phillips
,
D. C.
, “
The Tensile Strengths of Notched Carbon Fiber and Glass Fiber Composites
,” Materials Development, School of Engineering and Applied Science,
University of California
at
Los Angeles
,
12
1971
.
7.
Kelly
,
A.
,
Reinforcement of Structural Materials by Long Strong Fibres
,
Metallurgical Transactions
 0026-086X, Vol.
3
,
09
1972
.
8.
Murphy
,
M. C.
and
Outwater
,
J. O.
, “
The Toughness of Reinforced Plastics
,” 28th Annual Technical Conference,
The Society of the Plastics Industry, Inc.
,
1973
.
9.
Chamis
,
C. C.
,
Hanson
,
M. P.
, and
Serafini
,
T. T.
, “
Designing for Impact Resistance with Unidirectional Fiber Composites
,” NASA TN D-6463,
08
1971
.
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