An investigation has been conducted into the effects of fatigue loading on the stiffness and strength degradation of composite laminates. An experimental test program using graphite/epoxy [±35]2s laminates has been conducted to generate meaningful data for this evaluation. Based on this investigation, a model is proposed to relate the stiffness degrada tion to the fractional life expended at a given stress level and also to the residual strength degradation. These models are restricted to specimens subjected to constant amplitude fatigue loadings.
Get full access to this article
View all access options for this article.
References
1.
Salkind, M.J."Fatigue of Composites," Composite Materials Testing and Design (Second Conference), ASTM STP 479ASTM, Philadelphia , pp. 143-169 (1972)
2.
Whitworth, H.A. and D.L. Jones."Development of a Model to Characterize the Stiffness Degradation of Composite Materials," Proc. Twelfth Southeastern Conference on Theoretical and Applied Mechanics (SECTAM XII), Pine Mountain, Georgia (1984)
3.
. Yang, J.N. and D.L. Jones."Load Sequence Effects on the Fatigue of Unnotched Composite Materials," Fatigue of Fibrous Composite Materials, ASTM STP 723ASTM, Philadelphia, pp. 213-231 (1981).
4.
Yang, J.N. and M.D. Liu."Residual Strength Degradation Model and Theory of Periodic Proof Tests for Graphite/Epoxy Laminates,"Journal of Composite Materials, 11:176-311 (1975)
5.
. O'Brien, T.K."Characterization of Delamination Onset and Growth in a Composite Laminate," Damage in Composite Materials, ASTM STP 775ASTM, Philadelphia, pp. 140-167 (1982).
6.
Whitworth, H.A."Static and Dynamic Stiffness Reduction of Graphite/Epoxy Composite Laminates Under Fatigue Loading," D.Sc. DissertationThe George Washington University, Washington, D.C. (1983 ).
7.
Jones, D.L. and H.A. Whitworth."The Effect of Cyclic Loading on the Stiffness Degradation of Angle-Ply Composite Laminates," Proc. of the Fifth International Congress of Experimental Mechanics, SESA (1984) .
