Composite Materials

· The tension-tension S-N curve for a uniaxial carbon-fiber reinforced epoxy matrix with V_f = 0.4 is shown. Most of the periodic load is carried by the fibers and fatigue damage to the matrix is slow.
· The fibers are susceptible to fatigue damage at higher loads. As they fail the matrix load is increased. This increases the probability of matrix damage and reduces the fatigue life of the composite.

From: Hull, "Introduction to Composite Materials," Cambridge (1992)