A Novel Method to In-Situ Characterize Fatigue Crack Growth Behavior of Nickel-Based Superalloys By Laser Thermography

The article introduces a novel method to in-situ characterize fatigue crack growth behavior in nickel-based superalloys using laser thermography. It addresses the challenges of existing methods by employing laser thermography to achieve non-contact, rapid detection of crack geometry and growth behavior. The method involves using a laser thermography system combined with a fatigue loading system to detect fatigue crack growth in real-time. The study highlights the advantages of laser thermography in detecting crack tips and characterizing crack closure effects, which are crucial for ensuring the structural integrity of aero-engine components. The method is validated through experimental results, demonstrating high accuracy in crack tip localization and crack growth rate measurement. Additionally, the article introduces a new parameter, Crack Opening Temperature Gradient (COTG), for characterizing crack closure effects, which provides a reliable and intuitive method for evaluating crack closure states. The study concludes with the successful in-situ detection of fatigue crack growth and characterization of crack closure effects under laboratory conditions, paving the way for future engineering applications.