Crack propagation is a research area that focuses on the study of how cracks in materials grow under various loading conditions. This research is important in understanding the mechanisms of material failure, such as in engineering structures, aircraft components, or biomedical implants. Researchers in this area use experimental techniques, such as fatigue testing and fracture mechanics, as well as numerical modeling to predict crack growth behavior and develop strategies to prevent catastrophic failure. By understanding how cracks propagate, engineers can design materials and structures with improved durability and reliability.