Verification of Life Prediction Methods for Aging Aircraft Structures

摘要

The purpose of this research is to verify methodologies for AFGROW developed inconjunction with Delivery Order 0006, Contract F33615-94-D-3212. The methodologies, which pertain to aging aircraft, include bonded repair of metallic structures, widespread fatigue damage, stress level effects on crack growth and load sequence effects on crack growth. AFGROW is a fatigue crack growth prediction code developed by Analytical Services and Materials, Inc. and the Air Force. This research is necessitated by the growing need to keep current aircraft in service well beyond their normal design lives. When cracks are discovered in inspection the components must be either repaired or replaced. In most instances it is not economically feasible to replace entire components. Therefore, repairing the damaged areas is both preferred and critical. Additionally, repairs must be made quickly so the aircraft may be returned to service as soon as possible. Also, it is important to be able to model and predict fatigue crack growth behavior (exposed to various spectrum loading situations) that were not accounted for when determining a component's design life.