In Aerospace engineering domain, the natural trend is to improve the products towards increased durability,
reliability while
preserving functionality, high strength-to-weight ratio, and, limiting costs. In this framework, the knowledge of the material behavior and its response to the in-service loading is of fundamental importance. Most of the components in
aerospace industry are typically designed for fatigue using the Palmgren/Miner method. This method, also known as the safe-life methodology, determines a “safe life” for the component from an assumed usage spectrum, associated maneuver stress levels, and the S-N / E-N curves for the component. However, the inability to quantify
reliability, the cost of retiring parts that probably have no damage, and the fact that the crack that usually results in aircraft part failure is not modeled, have all led toward the damage tolerance design approach being implemented. The fatigue damages develop in stages where defects nucleate in initially undamaged regions and then propagate in a stable manner until, if the cracks are not detected in time, catastrophic failure occurs. The understanding of the mechanisms for both defect nucleation and evolution is therefore a key issue. Moreover, from the engineering point of view, clear and straightforward Damage Tolerance design methodologies are needed