Simulation of Fatigue Damage in Quasi-Isotropic Open-Hole Tension Coupon using the Kinetic Theory of Fracture

Progressive failure simulations of a quasi-isotropic laminate in open-hole configuration subject to constant amplitude tension-tension fatigue loading are conducted as part of the Damage Tolerant Design Principles program organized by the Air Force Research Laboratory. The laminate is made from unidirectional IM7/977-3 plies, which are composed of intermediate modulus carbon fibers and a toughened epoxy matrix. The simulated behavior of the material was characterized using fatigue loaded unnotched coupon data that was government furnished and the commercial software Autodesk Helius PFA was used to model the non-linear response of the material. Results from blind simulations were benchmarked against experimental measurements and X-rays. A second round of simulations was conducted where the modeling strategy was modified to improve correlation with experiment.