Fatigue analysis is a method used to assess the durability and lifespan of materials and structures under repeated loading conditions. It helps engineers predict when a material might fail due to the accumulation of microscopic damage over time, which can occur even if the loads are below the material's ultimate strength. This analysis is crucial in fields like aerospace, automotive, and civil engineering. The process typically involves calculating the number of cycles a material can endure before failure, often using techniques like S-N curves or finite element analysis. By understanding fatigue behavior, engineers can design safer and more reliable products, ensuring they perform well throughout their intended lifespan.