A Nonlinear Multiscale Computational Framework for Fiber‐Reinforced Liners in Pipeline Rehabilitation

Aging pipeline infrastructure presents a significant global challenge, particularly within urban water management systems. Fiber‐reinforced composite liners have emerged as a trenchless and economical solution for pipeline rehabilitation. However, the mechanical reliability and long‐term structural integrity of these liners, especially when cured at ambient temperature, remain insufficiently understood across multiple scales. This knowledge gap currently hinders their widespread adoption in engineering practice. This study presents a comprehensive multiscale investigation into ambient‐cured composite liners, employing material characterization, mesoscale damage analysis, and full‐scale structural modeling. Microscale analyses highlight that the quality of interfacial bonding between the resin and fibers critically influences damage initiation mechanisms. At the mesoscale, simulations reveal the efficacy of felt‐reinforced configurations in dispersing loads and delaying crack propagation. Macroscale finite element analysis further identifies the optimal fiber orientation, weaving angle, and felt thickness to maximize mechanical stiffness and minimize structural deformation. Compared to conventional heat‐cured systems, ambient‐cured liners demonstrate comparable stiffness and load‐bearing performance when interfacial bonding is optimized. These results provide a mechanistic explanation for the variability in previous experimental findings and delineate an engineering design envelope for reliable liner deployment. The findings offer a physics‐informed framework for the performance‐based design of sustainable rehabilitation technologies in aging pipeline networks.