X-ray computed tomography analysis of damage evolution in open hole carbon fiber-reinforced laminates subjected to in-plane shear

The deformation and damage mechanisms during tensile deformation of [±45]2s open hole carbon fiber composite materials were quantitatively analyzed by means of image analysis of XCT data. Damage developed progressively in each ply with deformation in two shear bands (parallel and perpendicular to the fiber direction) at ±45° with respect to the loading direction, i.e. cracking started from these shear bands and grew following the fiber direction until encompassing the whole laminate width. Matrix cracking and fiber rotation in both types of shear bands presented different features, which were quantified by means of image processing from XCT data. A small delamination developed around the hole at the intersection from +45° and −45° cracks directions in adjacent plies. However, this delamination does not progress excessively with deformation until the end of the test, when fracture was triggered by the sudden propagation of two main delamination cracks tangent to opposite sides of the hole in the shear band parallel to the fiber direction.