ABSTRACT Fatigue failure in aerospace structures is critically influenced by stress concentrators such as notches, which reduce service life and compromise safety. This study experimentally investigates the fatigue behavior of Al7075‐T6 alloy under rotating bending ( R = −1, 60 Hz), considering notched and unnotched conditions. Two advanced techniques are introduced to predict early fatigue damage. First, the time to first failure concept establishes conservative, reliability‐based safe life limits, based on the design criterion that a component must function for a predetermined period. This approach enables designers to reduce material use, fuel consumption, and operational costs, key targets in aerospace applications. Achieving high reliability requires life penalties of up to 97%. Second, stiffness degradation is introduced as an early‐life failure indicator, offering a sensitive and proactive method to detect internal damage before final fracture. This integrated framework enhances fatigue life prediction and supports safer, lighter, and more efficient aerospace structures.
Khashaba et al. (2025) studied this question.