Investigations on 355 nm nanosecond-picosecond dual-pulse laser enhanced ablation of carbon fiber reinforced polymer

Carbon fiber reinforced polymer (CFRP) composites find extensive utilization in aerospace applications due to its exceptional structural and mechanical properties. However, the inherent characteristics of CFRP composites pose challenges for conventional machining techniques to achieve efficient and high-quality processing. This work proposed a nanosecond (ns)-picosecond (ps) dual-pulse laser processing method. A theoretical model of ns-ps double-pulse laser enhanced ablation was established. The impact of the free electron density evolution process on the energy absorption process was analyzed. The temporal and spatial distributions of temperatures in the ablation region under diverse laser irradiations were compared. The evolution mechanism of ablation morphology was thus characterized. Based on numerical simulations and experiments, the effects of time delay and pulse energy ratio on the depth and morphology of ns-ps double-pulse laser processing were determined. Through-hole processing experiments were conducted on CFRP composites with a thickness of 2 mm. The experimental results show that employing a time delay of 0 and the ps-ns pulse energy ratio of 1:4 results in a small taper. Additionally, no visible damage, such as fiber delamination or resin decomposition, was observed. Excellent through-hole quality was obtained while achieving high processing efficiency. These theoretical and experimental findings establish a robust foundation for efficient and high-quality processing of CFRP composites and other composite materials.