Fatigue behavior of cross-ply glass-fiber epoxy composites including the effect of fiber-matrix interphase

The effect of glass-fiber epoxy interface in cross-ply reinforced composite s on the fatigue behavior is studied throughout this: paper. The sensitivit y of the interphase on fatigue life of cross-ply laminates is shown by a sh ift of the S-N curve to approx. 30% higher applied maximum loads for the co mposites with well-bonded fibers. Further, the damage as measured by stiffn ess reduction is more significant for the composites with poor bonded and c ommercial sized fibers than was found for EP sized ones. The loss energy is shown to be a sensitive tool to characterize the nature of fiber-matrix ad hesion. The loss energy for composites with poor adhesion between fiber and matrix results in significantly higher amounts of consumed energy during a single stress-strain than those composites containing well-bonded fibers.