Failure of delaminated carbon/epoxy composite beams under cyclic compression

摘要

Experimental study of the response of laminated [(45/90/-45/0)_6]_s carbon/ epoxy virgin and pre-cracked composite beams to compressive cyclic loading is reported. The development of failure, in the form of delaminations, recorded continuously on video tape during the tests, revealed formation of delaminations close to the external faces of the beam. Some of the delaminations developed instantly and some propagated along the beam in jumps. Total failure occurred when the stress in the central 'undamaged' section of the beam reached a critical value. Calculation of the buckling load of unsymmetric laminated beams supports the experimental finding that a pre-crack close to the center of the specimen has no effect on the fatigue behavior of the beam. Prediction of time to first delamination crack, based on previous results, agree with the present experimental observation.