FATIGUE FAILURE OF MULTIDIRECTIONAL LAMINATE

A general fatigue failure criterion for laminates made of unidirectional laminae in different directions is evolved, based on previously developed concepts. A limited number of fatigue functions are measured from tests on single lamina and one type of angle-ply laminate. The fatigue functions used in the fatigue failure criterion enable prediction of the fatigue life of any laminate. An extensive tension-tension fatigue testing program for Eglass/epoxy symmetric-balanced laminates with various reinforcement angles has been carried out in order to test the validity of the theory. The test results were in good agreement with the predicted fatigue failure mode relevant to the specific laminate. In some cases there is shifting from one failure mode to another due to the progressive nature of the fatigue failure. © 1979 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.