Crush tests have been performed on flat unidirectional non-crimp fabric (NCF) coupons with differentfibre orientations as part of the validation of a ply-based damage model for crash. The fibre off-axisangle with respect to the crushing direction ranged from 0º to 90°. The results of the tests indicate thatthe crush stress remains unchanged for off-axis angles between 0° and 15°. The failure mode in thesespecimens was out-of-plane kinking. For 20° and 25° off-axis angles the crush stress dropped 20% andevidence of out-of-plane kinking were harder to find. For 45° off-axis angle a network of matrixcracks develops in the specimen and for 90° off-axis angle a brittle shear failure is observed. It issuggested that the out-of-plane kinking is promoted because of the natural waviness of NCF materialsand that the high in-plane shear stress generated from 20-25° off-axis loading results in a transitionfrom out-of-plane kinking to in-plane kinking. These hypotheses need, however, to be verified by anextended failure analysis of the crush specimens.
Paper ID. 3827