fatigue limit

The fatigue limit is the maximum stress level a material can withstand repeatedly without experiencing failure over time. When a material is subjected to cyclic loading—like bending, stretching, or compressing repeatedly—it can eventually develop tiny cracks that grow and cause it to break. The fatigue limit indicates the threshold below which these repeated stresses won't cause failure, even after many cycles. Understanding this limit helps engineers ensure structures like bridges, airplanes, and machinery are designed safely, by avoiding stress levels that could lead to long-term damage or failure through ongoing use.