Delamination R-curve behavior of curved composite laminates

The effect of curvature on the delamination R-curve behavior of composite unidirectional laminates is investigated in both the experimental and numerical manners. The flat and curved double cantilever beam specimens with different radii of curvatures are manufactured and tested subjected to mode I loading. A new data reduction method is developed for the curved specimens by adopting the Timoshenko curved beam theory. Experimental R-curves indicate that curvature has no effect on the initiation toughness, while it significantly affects the steady-state toughness and fiber bridging length. Variation of the steady-state toughness and fiber bridging length vs. The different curvatures is formulated for the curved specimens with R/h > 25 (R/h: the ratio of the radius of curvature to thickness). Finally, delamination propagation is simulated in the curved double cantilever beam specimens in commercial finite element software, ABAQUS, by applying both the virtual crack closure technique and cohesive zone model.