Multi‐Scale Characterization of Damage Monitoring and Fiber Failure in Embedded Optical Fiber Composites Under Tensile Loading

Optical fiber sensors offer significant potential for structural health monitoring (SHM) of composite materials, yet their internal integration may introduce microstructural disturbances and local stress concentrations. Using computed tomography (CT), scanning electron microscopy (SEM), and real‐time X‐ray imaging, this study investigates the effects of embedded optical fibers on the tensile properties and damage evolution of glass fiber‐reinforced laminates via mechanical testing, finite element simulations, and multi‐scale characterization. Results show that embedding fibers along the reinforcement direction does not significantly compromise tensile strength, while incorporating two fibers yields a slight increase in tensile modulus. Embedded optical fibers provide reliable strain measurements with acceptable accuracy compared with conventional strain gauges. Multi‐scale observations reveal that pore‐rich regions around embedded optical fibers act as preferential sites for crack initiation, with subsequent propagation occurring mainly along the fiber direction. Dominant failure mechanisms include matrix cracking, interfacial debonding, glass fiber fracture, and fiber pull‐out. Notably, optical fiber failure precedes matrix failure, serving as an effective early‐warning indicator of impending structural failure. This work quantifies mechanical perturbations induced by embedded optical fibers and elucidates pore‐damage coupling, establishing a basis for optimized sensor integration in high‐performance composites.