Delamination propagation in a multi-directional woven composite DCB specimen subjected to fatigue loading

Double cantilever beam (DCB) specimens fabricated from a graphite/epoxy (G0814/913) woven prepreg containing a straight through notch were tested by means of constant amplitude fatigue. The specimen was composed of 15 layers with fibers alternating between the weft and warp in the 0°/90° and the +45°/−45° directions. Eight fatigue tests were carried out to determine the delamination growth rate da/dN vs the nearly mode I cyclic energy release rate ΔGI. Comparison of the delamination growth rate was made to the crack propagation rate of an aluminum alloy. It was found that a crack in the aluminum will grow faster but will be less sensitive to uncertainties or changes in load level.