Understanding the Interlayer Behavior of Fused Deposition Molded Polyether‐Ether‐Ketone: Multiscale Prediction and Experimental Analysis

Polyether‐ether‐ketone (PEEK) manufactured via fused deposition modeling (FDM) has demonstrated significant potential in aerospace applications, driven by its exceptional properties such as high strength, outstanding high‐temperature resistance, and other superior characteristics. However, the persistent issue of weak interlayer bonding strength induced by FDM processing remains unresolved, with its mechanisms not yet thoroughly elucidated. In this work, a multiscale approach combined with the molecular dynamics (MD) and finite element analysis (FEA) is proposed to characterize the failure behavior of interlayer bonding of FDMed PEEK. A molecular‐scale model of FDM interface mechanical performance for PEEK extruded and deposited layers is established using polymer consistent force field (PCFF). Utilizing this model, MD simulations are conducted, yielding PEEK interlayer performance and interfacial behavior. These parameters are incorporated as input parameters for macroscale FEA, enabling simulation analysis of PEEK interfacial failure behavior. Therefore, the interlaminar shear strength of PEEK is predicted using this approach and subsequently validated through experiments.