Optimization of fan blade cross-sections for improved fatigue life and weight reduction

This paper presents an optimized design approach for hollow-structured fan blades, aiming to improve both fatigue life and weight reduction. The design process incorporates static and dynamic analyses to evaluate fatigue loads, structural stability, and key design variables for hollow structures. The model focuses on the PW-4000 engine fan blade, utilizing Ti-4Al-6V alloy and an e59 airfoil profile. Stress, modal and fatigue analyses confirmed structural safety under high-speed rotation and identified critical factors influencing fatigue life. The optimization employed the Box-Behnken design and the modified extensible lattice sequence (MELS) method to refine the blade's cross-sectional shape. The third iteration of optimization achieved the best performance, balancing a target fatigue life of over 10,000 cycles and weight reduction. The study emphasizes that optimizing the blade's internal structure can enhance reliability while maintaining lightweight design goals, minimizing both overdesign and the risk of structural failure.