Multiscale Analysis of CFRP Laminates Including the Effect of Fiber Waviness

Abstract

This paper proposes a numerical analytical method for carbon fiber reinforced plastic (CFRP) laminates, where fiber orientation is disturbed due to manufacturing defect. In the CFRP laminates, it is not unusual to find internal microscopic defects including fiber waviness, voids, or resin pockets. Among them, fiber waviness has a strong effect to the compressive strength of the CFRP. Therefore, it is very important to simulate the effect of the fiber waviness on the stress distribution in the CFRP laminates. In this paper, the authors propose a numerical method which can include various modes of fiber waviness by simple method. In this model, fiber waviness is introduced as a combination of geometrical translation of the position of the node, and change of the material orientation. The analytical method is formulated based on homogenization method together with finite element method, and fiber waviness is considered by using perturbation method. Fiber waviness is introduced as an input to the calculation, and the calculation is always done using the idealized perfect geometry, thanks to the utilization of perturbation method. This has a distinct advantage in numerical calculations where the same mesh can be used for a series of fiber waviness. The method is implemented using general-purpose finite element code ABAQUS. The proposed method is validated by comparing the results to those of a conventional calculation. The results demonstrate that the proposed method can accurately capture the stress distribution when the amplitude of the imperfection is small.