Prediction of Creep Fatigue Interaction for Turbine Engine Components

The VAATE Durability Focus Area mission is to make high performance turbine engine technology affordable to the user through proactive development of advanced technologies to prevent component failure, increase engine life & reliability, enhancereparability and reduce costs for improved warfighter effectiveness. Of particular consideration under VAATE I will be future requirements for long range strike aircraft. These aircraft will fly at mach 2-4 cruise capability, have 30% increased missionradius and 3 times sortie generation rate, and will be required to have fast response to time critical targets. Under high temperature, mechanical creep can affect material grain boundaries such that fatigue occurs. Creep induced fatigue is a lessunderstood, unique and somewhat unpredictable failure mechanism. In order to meet VAATE affordability goals, physics-based software must be developed to predict creep-fatigue affects in order to avoid conventional total accumulated cycle (TAC)-based lifingand high operational costs. The proposed project will demonstrate feasibility for developing probabilistic, physics-based prediction software for thermo-mechanical failure (TMF). Phase I will focus on creep-fatigue damage interaction. Based on analysisof F100 and F110 data, it is estimated that 75-85% of unscheduled removals are due to durability and subsystem issues. The proposed technology will help enable accomplishment of established VAATE durability goals: double component life; reduce repair costby 30%; and reduce development time by 25%.