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ASTM Selected Technical Papers
Foreign Object Impact Damage To Composites
By
LB Greszczuk
LB Greszczuk
1
McDonnell Douglas Astronautics Co.
,
Huntington Beach, Calif. symposium chairman
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ISBN-10:
0-8031-0357-3
ISBN:
978-0-8031-0357-3
No. of Pages:
252
Publisher:
ASTM International
Publication date:
1975

An investigation of the response of a graphite-epoxy material to foreign object impact was made by impacting spherical projectiles of gelatin, ice, and steel normally on Modmor II/PR-286 flat panels. The observed damage was classified as transverse (stress wave delamination and cracking), penetrative, or structural (gross failure): the minimum, or threshold, velocity to cause each class of damage was established as a function of projectile characteristics. Steel projectiles had the lowest transverse damage threshold (30 m/s), followed by gelatin (170 m/s) and ice (215 m/s). Making use of the threshold velocities and assuming that the normal component of velocity produces the damage in non-normal impacts, a set of impact angles and velocities was established for each projectile material which would result in damage to composite fan blades. Analysis of the operating parameters of a typical turbine fan blade shows that small steel projectiles are most likely to cause delamination and penetration damage to unprotected graphite-epoxy composite fan blades.

1.
Tsai
,
Y. M.
and
Kolsky
,
H.
,
Journal of Mechanics and Physics of Solids
 0022-5096, Vol.
15
,
1967
, pp. 263–278.
2.
Timoshenko
,
S.
and
Goodier
,
J. N.
,
Theory of Elasticity
,
McGraw-Hill
,
New York
,
1951
, p. 383.
3.
Goldsmith
,
W.
,
Impact
,
Edward Arnold Ltd.
,
London
,
1960
, pp. 108–209.
4.
Timoshenko
,
S.
,
Zeitschieft fur Mathematik und Physik
, Vol.
62
,
1913
, p. 198.
5.
Cook
,
T. S.
and
Preston
,
J. L.
, Jr.
, “
Impact Behavior of Graphite-Epoxy Simulated Blade Specimens
,” to be published.
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