Microscopic Modeling and Failure Mechanism Study of Fiber Reinforced Composites Embedded with Optical Fibers

Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring. However, there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fibers, and the detailed mechanism of how embedded optical fibers affect the micromechanical behavior and damage failure processes within composite materials remains unclear. This paper presents a micromechanical simulation analysis of composite materials embedded with optical fibers. By constructing representative volume elements (RVEs) with randomly distributed reinforcing fibers, the optical fiber, the matrix, and the interface phase, the micromechanical behavior and damage evolution under transverse tensile and compressive loads are explored. The study finds that the presence of embedded optical fibers significantly influences the initiation and propagation of microscopic damage within the composites. Under transverse tension, the fiber-matrix interface cracks first, followed by plastic cracking in the matrix surrounding the fibers, forming micro-cracks. Eventually, these cracks connect with the debonded areas at the fiber-matrix interface to form a dominant crack that spans the entire model. Under transverse compression, plastic cracking first occurs in the resin surrounding the optical fibers, connecting with the interface debonding areas between the optical fibers and the matrix to form two parallel shear bands. Additionally, it is observed that the strength of the interface between the optical fiber and the matrix critically affects the simulation results. The simulated damage morphologies align closely with those observed using scanning electron microscopy (SEM). These findings offer theoretical insights that can inform the design and fabrication of smart composite materials with embedded optical fiber sensors for advanced structural health monitoring.