NASA/TM-2006-214532 Simulation of Delamination Propagation in Composites Under High-Cycle Fatigue by Means of Cohesive-Zone Models Albert Turon Escola Politècnica Superior, Universitat de Girona, Girona, Spain Josep Costa Escola Politècnica Superior, Universitat de Girona, Girona, Spain Pedro P. Camanho Faculdade de Engenharia, Universidade do Porto, Porto, Portugal Carlos G. Dávila Langley Research Center, Hampton, Virginia December 2006