Mechanical behavior of angle‐ply PEEK/carbon fiber laminates: Theory/experiment correlation

Abstract Regular symmetrical laminates of the {+α/−α/+α/−} sym. type were manufactured and tested using established methods. Tensile characteristics—elastic modulus and the ultimate stress/strain characteristics—were determined in the form of angular dependences on the ply‐angle α. The same mechanical properties were also simulated adopting a reported theoretical model. The correlation between the experimental and the predicted values shows an excellent agreement for the laminate stiffness. On the other hand, the fit for the ultimate properties was unsatisfactory except under conditions of linear, elastic response encountered for α→ O and 90°. Generally, a qualitative correlation has been obtained for the ultimate strength, but no relation has been established for the ultimate strain. A mechanism of fiber reorientation during loading, i.e. closing of the ply angle with the increasing strain has been found to be responsible for exceptionally non‐linear stress‐strain response in the range 30<α<60°. Coupon width and strain rate have both been found to have little effect on the ultimate properties.