A multiscale analysis framework for formation and failure of the thermoplastic interface

Formation and failure of the interface determine the quality of thermoplastic composite structures. However, accurate prediction of interface strength evolution during advanced manufacture is still challenging due to the multiscale feature of thermoplastics, which hinders the design of composites processing and analysis of structure reliability. Here, we develop a multiscale model for formation and failure of thermoplastic interface. The reptation model of polymer chains is used to describe the chain density evolution at the interface during manufacture. Then, by releasing the rigid-bond assumption in the traditional freely-jointed-chain model, the Lennard-Jones potential function is incorporated to model polymer chain scission. Finally, chain-length dispersity, individual chain scission, and chain density reduction are incorporated to model the interface failure. The model predictions are in good agreement with the experimental results of composites welding, indicating that the developed model can be used to analyze the interface strength evolution of thermoplastics in the advanced manufacturing processes.