Full-size mesoscopic model for in-plane/out-of-plane shear behavior of 3D orthogonal woven composites under cyclic hygrothermal aging

The shear performance of 3D orthogonal woven composites (3DOWCs) under hygrothermal aging is critical for ensuring long-term reliability in aerospace and marine applications. This study systematically examines the in-plane and out-of-plane shear behaviors of 3DOWCs subjected to cyclic hygrothermal aging, combining experimental characterization with computational modeling. Iosipescu V-notch beam shear and short-beam shear tests were conducted to evaluate the evolution of shear performance. Concurrently, a full-scale mesoscopic finite element model was developed, which incorporates degraded constituent properties, to predict the shear response and damage evolution. The simulation and experimental results demonstrated good consistency, with the prediction error for shear strength remaining below 10 %. It was observed that after hygrothermal aging, the in-plane shear strength and out-of-plane shear strength decreased by up to 14.3 % and 24.3 %, respectively. The observed in-plane shear anisotropy (weft/warp strength ratio=1.18) and out-of-plane shear's loading-position dependence (±15.0 % variation) both originate from the Z-binder yarns' through-thickness constraint effect during stress redistribution. Damage progressed from interfacial debonding to continuous bands, initiating at yarn crossovers and propagating along shear direction, with accelerated initiation in aged specimens but unchanged failure sequence.