Fatigue-driven degradation remains one of the leading causes of structural failure in engineering systems, especially in polymer and composite materials used in various applications including aerospace, automotive, wind energy, and civil infrastructure. Unlike metals, polymers and fiber-reinforced composites exhibit complex time-dependent, viscoelastic, and anisotropic fatigue behaviors governed by microstructural evolution, environmental interactions, and multiscale damage mechanisms.

This special session aims to bring together researchers and industry experts to discuss recent advances in experimental characterization,  and multiscale modeling for polymers and composite materials under cyclic loading and addressing lifetime prediction, and structural health monitoring. Topics of interest include crack initiation and propagation, fatigue-environment coupling, high- and low-cycle fatigue behavior, fatigue in additive-manufactured polymers, hybrid composites, durability under thermo-mechanical loading, and innovative design strategies for enhanced fatigue resistance.