A coupled thermo-chemo-mechanical peridynamic model for predicting process-induced residual stress in fiber-reinforced polymer composites

Fiber reinforced polymer (FRP) composites have extensive applications in aerospace, automobile, marine and sports industries, however, the process-induced residual stress developed during the cure process can lead to microcracks and weaken the macroscopic mechanical performance. In this work, we developed a multiscale PD framework for modeling thermo-chemo-mechanical behaviors of FRP composites for the first time. The whole cure process is modeled by a macroscale thermo-chemical coupling behavior of the FRP specimen followed by a microscale thermo-chemo-mechanical coupling process of the representative volume element (RVE) taken from the macro specimen. After the multiscale cure modeling, the resulted residual stress distribution is maintained when applying the mechanical loading. The proposed PD framework was validated by examining the temperature and degree of cure histories and the stress-strain curves against experimental data. The effects of periodic boundary condition (PBC) treatments, fiber content, fiber distribution and chemical shrinkage are explored. Cure-induced residual stress can amplify the local stress concentration and damage in the fiber‒matrix interfaces. Results show that PBC treatments have negligible influence on the final damage distribution while the fiber content and distribution can pose huge impact on the strain and stress history of the RVE. In addition, chemical shrinkage can complicate the stress state and impact the mechanical response of composites. This model can serve as a potential tool for predicting the process-induced residual stress and damage and contributes to improved composites designs.