Material fatigue refers to the gradual weakening of a material due to repeated stress or strain over time. When a material is subjected to cyclic loading, such as bending or twisting, tiny cracks can develop within its structure. These cracks can grow larger with each cycle, eventually leading to failure even if the material is not subjected to a load that exceeds its ultimate strength. This phenomenon is particularly important in engineering and manufacturing, as it can affect the lifespan and safety of structures and components. Common examples include the fatigue of metals in aircraft wings or bridges, where constant movement and stress can lead to catastrophic failures if not properly monitored and managed.