Strain Response Frequency Function-Based Mechanical Damage Indentification by Fiber Bragg Grating Sensors

Local damages in mechnical structure affect machine´s safety and performance, and more severely can cause irreversible structural fracture. Local damage is often hard to be identified by displacement-related parameters, but strain-related damage identification index can reflect its location and severity. Successful damage identification by strain-related index depends on distributed measurement of structural strain field, with the advantages of tiny size, Light weight, anti-electromagnetism interference and wavelength division multiplexing, fiber bragg grating (FBG) sensor is a exceptional choice for strain field measurement of mechanical structures. In this work, FBG distributed sensing is suggested to apply to strain field measurement of mechanical structure, based on strain frequency response function, a damage identification index adapted to FBG strain sensing is proposed. Numerical analysis and experimental tests proved that this method combining strain frequency response function-based index with FBG distributed sensing is sensitive to local damage, and is a simple but effective way to detect damage of mechanical structures.