Decomposition and vulnerability of CFRP under laser impact with powers of up to 120 kW

The use of drones and Unmanned Aerial Vehicles (UAVs) poses an increasing aerial threat in both military and civilian sectors. High-Energy Laser (HEL) systems emerge as a promising way to countermeasure these threats with excellent precision and minimal collateral damage. Considering that UAVs and drones are predominantly constructed from lightweight construction materials like Carbon Fiber-Reinforced Polymer (CFRP), investigating the vulnerability of this material class becomes crucial, as it directly impacts the resistance of these platforms against high-energy laser countermeasures. This study presents research on HEL interactions with Carbon Fiber-Reinforced Polymer (CFRP) composites, exploring the effects of Continuous Wave (CW) laser powers of up to 120 kW. We established a laboratory environment that meets the demands of operational safety requirements for laser processing of CFRP including a robot-controlled sample exchange and automatic laser beam shut-off. The interaction of the laser with the composite material was evaluated using high-speed images showing the rapid expansion of a smoke cloud, that contains fragments of fibers and a partially ionized plasma. Experiments reveal a decrease in perforation times with increasing laser power, which can be described by a power law. A detailed examination of the damaged samples, visually and via micro-focused computed x-ray tomography, offers insights into heat affected zones and ablation dynamics. Furthermore, Compression After Impact (CAI) tests assess the residual strength of the irradiated CFRP panels. A decrease of the compressive strength of a factor of about two is observed. The outcomes of this research contribute to the understanding of CFRP behavior under extreme laser conditions, providing valuable knowledge of the dynamic interactions between high-energy lasers and complex composite materials, highlighting potential applications for countermeasures in defense technology.