Investigations on 355 nm picosecond laser machining of carbon fiber reinforced polymer composites

Carbon fiber reinforced polymer (CFRP) composites have emerged as excellent performance structural materials with a wide range of applications in the aerospace industry. Ultrafast laser is a promising and versatile tool for manufacturing these composites due to its advantages of high peak intensity and ultrashort pulse duration. Herein, a theoretical model based on the Fokker–Planck law and the two-temperature equation, i.e. the ultrafast responses of a two-dimensional heterogeneous material assembly of resin matrix padded with carbon fiber reinforced phase irradiation by 355 nm picosecond laser is established. The evolution of laser-excited free electron density is analyzed, and the relationship between the optical properties of substrate and electron density is revealed. The spatial and temporal distribution of electron and lattice temperatures are thus characterized. The ablation thresholds of resin and carbon fiber are determined, the accuracy of which are verified by experiments. On this basis, orthogonal experiments are conducted to analyze the influence law of process parameters on the ablation depth and heat affected zone (HAZ) width. Optimized parameter groups are discovered to realize the high-quality machining of CFRP composite with considerable depth-to-width ratio and limited HAZ width. This work offers new insight into the fundamental regimes and high-quality machining for picosecond laser manufacturing of CFRP composites.