Studies of femtosecond laser machining of sandwich-structured GFRP composites

Glass fiber-reinforced plastic (GFRP) composites have been increasingly utilized in the aerospace industry owing to their distinctive properties such as high mechanical strength, low density, and design flexibility. However, conventional machining methods such as drilling, milling, and sawing are usually limited when machining these materials due to the caused severe tool wear, composite delamination, and thermal damage. Herein, a femtosecond laser machining method was explored to realize precision machining of sandwich-structured GFRP composites with significantly suppressed thermal damage, burr formation, and delamination. Comprehensive machining quality was evaluated on the basis of penetration depth, surface morphology, and machining efficiency through optimizing the main parameters of laser fluence, scanning speed, and laser scanning repetitions. Results showed that the smoothest cut surface with a clean edge and minimal heat-affected zone was obtained at a laser fluence of 9.21 J/cm2. Within the experimental range, the higher scanning speed resulted in smoother cut surfaces and reduced thermal defects. The study provides experimental evidence for optimizing femtosecond laser micromachining of GFRP composites and contributes to a deeper understanding of laser–composite interaction mechanisms.