Cross-scale modeling and process parameter optimization for drilling and milling of woven CF/PEEK composites

Objective To address common machining defects including delamination, hole-edge burrs and out-of-tolerance aperture during drilling-milling hole-making of woven carbon fiber reinforced poly ether ether ketone (CF/PEEK) composites, which deteriorate the structural service accuracy, this study investigates cross-scale modeling and process optimization for drilling-milling hole-making under thermo-mechanical coupling conditions, so as to provide theoretical support for the high-precision hole-making process.

Method According to the real structural characteristics of woven CF/PEEK composites, the material mechanical properties and mesoscopic constitutive relation are characterized. A cross-scale finite element model considering thermo-mechanical coupling effect is established for drilling-milling hole-making. Matching drilling-milling experiments are carried out. Axial force, machining temperature field and hole-wall micro-morphology are taken as evaluation indicators to verify model accuracy and analyze the evolution law of hole-wall morphology. The thermo-mechanical response evolution of the material is explored through iterative simulations with multiple groups of process parameters, and the optimal drilling-milling parameters are determined by grey relational analysis.

Results The constructed cross-scale model can accurately characterize the thermo-mechanically coupled damage evolution behavior of woven CF/PEEK composites in drilling-milling. The deviation between simulated and experimental steady state axial force for milling is less than 3%, and the maximum axial force deviation for drilling is approximately 6%. The calculation deviations of steady temperature field for both processes are controlled within 11%. The optimized process parameters can effectively suppress the initiation and propagation of hole-making defects.

Conclusion The cross-scale finite element model has reliable accuracy and can precisely simulate the thermo-mechanical coupled damage process of woven CF/PEEK composites during drilling-milling. The optimized process parameters can significantly improve the hole-making quality, which provides an effective theoretical basis for the engineering application of high precision hole-making technology for similar composite materials.