Thermal defect characterization and heat conduction modeling during fiber laser cutting carbon fiber reinforced polymer laminates

High-power fiber laser has been proven to be feasible for cutting carbon fiber reinforced polymers with several advantages including noncontact force, high efficiency and flexibility, while the characteristics of thermal damage and heat conduction in materials are not yet fully understood. Continuous-wave fiber laser was applied in this work to cut 2.0-mm-thick carbon fiber reinforced polymer laminates with different layup configurations. The influence of processing parameters including laser power and cutting speed on thermal damage was investigated. The characteristics of various thermal defects on different positions of machined surface were analyzed using high-resolution SEM and mathematical models. Interestingly, swollen fibers were observed and they connected together to form irregular swollen masses. According to further analysis on the initial heat distribution, it showed that cutting speed was the main factor affecting heat accumulation. In addition, modified heat conduction model was developed to analyze heat transfer within unidirectional carbon fiber reinforced polymer laminates in comparison with experimental results, which can be applied to predict heat affect zone during high-power fiber laser cutting composite materials.