Characterization of Functional and Structural Fatigue Using Infrared Thermography

Fatigue failure in components subjected to variable loads is a common issue in engineering, necessitating the optimization of characterization techniques. The assessment of the fatigue limit of the materials involved is crucial in the high-cycle fatigue regime. However, determining this limit requires executing numerous demanding and time-consuming tests, which can be costly. Consequently, there is growing interest in developing alternative methods that provide faster and more efficient estimations. Among these methods, thermal approaches based on temperature changes occurring in materials under variable loads have gained significant attention, particularly with the advent of infrared thermography (IRT). IRT-based methodologies offer a notable advantage over conventional methods by enabling the estimation of fatigue limits at higher speeds. This advantage is particularly beneficial for components manufactured through additive manufacturing, where optimizing build parameters is essential. Furthermore, the thermoelastic effect enables thermoelastic signals to provide valuable insights into crack tip location and the estimation of fracture mechanics parameters. The combined utilization of IRT and digital image correlation (DIC) also offers a powerful approach for characterizing functional fatigue and obtaining comprehensive insights into phase transformations in functional materials. This synergistic combination allows for the acquisition of detailed information and enables more efficient characterization of functional fatigue. This study explores various applications of IRT for characterizing functional and structural fatigue in different materials. Additionally, it investigates thermographic estimation methods for determining fatigue crack tips in CT specimens. The study analyzes the applications of IRT both independently and in combination with other non-contact techniques.