Remaining life estimation by fatigue damage sensor

A fatigue damage sensor (FDS) that enables an evaluation of the remaining life of welded steel structures has been developed. The FDS is a type of sensing gauge, which is stuck on the steel structure and indicates the magnitude of the stress fatigue damage. The FDS is constructed with two metal foils. A fatigue crack initiates on the FDS when it experiences a certain magnitude duration of varying amplitude strain. The length of the fatigue crack growth is converted into structural fatigue damage based on the crack growth properties of thin metal. The size of the FDS is small enough to be able to pick up the structurally concentrated stress in the vicinity of welding beads. A computational method was used to design the configurations. Its capability was verified through a cyclic loading fatigue test with a large steel beam simulating a part of a steel bridge.