Experiments and simulations on the anisotropic behavior of carbon woven fabric-reinforced shape memory polymer composites

This study integrates experimental investigations with advanced constitutive modeling to elucidate the anisotropic behavior in carbon woven fabric-reinforced shape memory polymer composites (SMPCs). By adjusting the alignment of carbon fabric layers during the layup process, SMPCs with various fiber orientations were fabricated. Subsequent experimental characterization of their thermomechanical and shape memory properties revealed several significant orientation-dependent phenomena. To elucidate the underlying mechanisms behind these observations and overcome the limitations of existing formulations, which fail to adequately explain the shape memory mechanisms and the viscoelastic yielding behavior observed experimentally, we developed a novel constitutive model for SMPCs based on the phase transition concept. A dual-phase decomposition strategy is introduced, wherein the rubbery phase is described as a coupling of the SMP's hyperelastic response and the fabric's orthotropic behavior, while the glassy phase combines SMP viscoelasticity with fabric kinematic constraints. To further quantify shape memory effects of SMPCs, the storage strain concept is integrated into the thermodynamic framework. Through energy decomposition, the constitutive equations are rigorously derived based on the Clausius inequality and Helmholtz free energy principles, with phase effectiveness factors incorporated to account for non-ideal behaviors. Good agreement between simulations and experimental results confirms the model's capability to predict anisotropic thermomechanical behavior and shape memory performance. This work provides a valuable theoretical tool and experimental basis for the design and optimization of SMPC-based structural systems.