SEDL / STP / STP569-EB / STP33163S

Fatigue Crack Propagation in 0°/90° E-Glass/Epoxy Composites

Mandell, JF
Research associate, Massachusetts Institute of Technology, Cambridge, Mass.

Meier, U
Head, Swiss Federal Laboratories for Testing Materials and Research (EMPA), Dubendorf,

Pages: 17    Published: Jan 1975

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Abstract

The mode of fatigue crack growth is described for a 0/90° E-glass/epoxy laminate under cyclic tension-tension loading. Crack growth appears to occur in a stepwise fashion with the crack remaining stationary for many cycles before each step of growth, whereupon a ligament of longitudinal ply at the crack tip is broken. A simple theory is described which assumes that the ligament at the crack tip is fatigued according to the S-N curve of the unnotched material. Using an assumed stress field and cumulative damage law, the number of cycles for initial growth from a notch and the rate of crack growth thereafter are predicted, and good agreement is demonstrated with experimental data.