X-ray computed tomography was used to obtain cross-sectional images of a unidirectional carbon fiber reinforced plastic, where fiber locations in each cross-sectional image were identified. The three-dimensional model with fiber waviness was developed by connecting the fiber locations along the fiber direction. Numerical simulation for the initiation and formation of a kink-band during axial compression was performed using the three-dimensional finite element model. The load was increased almost linearly until it reached the compressive strength, after which both load and displacement were decreased, showing snap-back behavior. The matrix yielded locally with the increased axial compression, and fibers started to fall due to insufficient support by the yielded matrix. A kink-band was formed with an increase in the yielded area, and thus, the initiation of a kink-band was defined as the local yielding of the matrix. It was also shown that the kink-band was formed at the longitudinal location at which the average of local fiber misalignment angles in the cross-section was relatively large.
