Failure modes and strength prediction of thin ply CFRP angle-ply laminates

In this paper, the tensile strength and failure modes of thin ply carbon fiber-reinforced polymer (CFRP) angle-ply laminates are investigated by experiments and predicted by Finite element method (FEM) and theoretical model. First, experiments are performed to evaluate the tensile behavior of thin ply CFRP angle-ply laminates fabricated with different fiber areal weights of prepreg (20,60,120 g/m²) and ply angle (15°, 30°). Experimental results show that thin ply angle-ply laminates present different failure modes, and also the tensile strengths do not increase monotonically with the decrease in fiber areal weight. Second, both theoretical and FEM models are established to predict the strength and failure modes of thin ply CFRP angle-ply laminates with different ply thickness and fiber volume fraction, also two competing mechanisms finally cause the non-monotonic change of strengths of thin-ply laminates which has good agreement with experimental results. Finally, a failure diagram of thin ply angle-ply laminates under tensile load is given, which shows different failure modes (fiber breakage, delamination and transverse matrix failure) for fiber areal weight (0–240 g/m²) and ply angle (0–90°). Also the delamination is suppressed and the fiber breakage is extended with the decrease of fiber areal weight in the ply angle range of 10°–25°.