Experimental and Numerical Study on the Compressive Failure of Composite Laminates with Fiber Waviness Defects

Fiber waviness defects are found in the inner surface of the hat-shaped stringers manufactured by a process system. In order to establish the acceptance criterion for the stringers with the fiber waviness defects, experimental testing and numerical simulation were carried out in this study. Specially induced fiber waviness defects of four pre-defined severity levels were manufactured and tested. A maximum of a 58.1% drop in compressive failure load is observed for the most severe level in the experimental results. A finite element model with progressive damage method and cohesive zone technique was developed to simulate the failure process and the impact of fiber waviness defects. The numerical simulation results of compressive failure load have a good agreement with experimental results qualitatively and quantitatively. In addition, two simple parameters, i.e., aspect ratio A/H and the number of plies with fiber waviness, are proposed to characterize the influence of the fiber waviness on the compressive failure load for the purpose of fast engineering quality checks.