Improving interlaminar shear strength of continuous carbon fiber reinforced PEEK via laser directed energy deposition: Experimental study and physically based modelling

Continuous carbon fiber reinforced polyetheretherketone (CCF/PEEK) composite exhibits great potential for aerospace applications owing to excellent temperature resistance, high impact toughness, and repairability. Additive manufacturing is a digital, moldless, and cost-effective process. However, the layer-by-layer forming process often results in inadequate interlayer bonding performance of the printed parts. The aim of this study is to enhance interlayer bonding performance of CCF/PEEK produced via laser direct energy deposition. Processing parameters were systematically investigated and results demonstrated that the interlaminar shear strength (ILSS) increases with higher laser power and compaction pressure, while it decreases with increased printing speed. The ILSS was improved by 99.7 %, reaching a maximum of 49.3 MPa. Furthermore, a physically based model, considering molecular chain diffusion and pore evolution mechanisms, was developed for predicting ILSS. This model can be integrated into finite element analysis as a user-defined subroutine to achieve full-field predictions of porosity and interlayer performance for additively manufactured parts.