Characterising the thermal effect of laser perforation on carbon fibre reinforced epoxy composites for the aerospace sector

With global climate goals driving the aviation industry to reduce emissions, there is a push to maximise fuel efficiency in current and future aircraft. This can be achieved by techniques such as Hybrid Laminar Flow Control (HLFC), which reduces drag by pulling airflow through perforated leading-edge surfaces, delaying the onset of turbulent airflow. Carbon fibre reinforced polymer composites (CFRP) are recognised as a viable alternative to certain aerospace materials due to their low weight and exceptional properties, with HLFC being one system that could benefit from their use. The outer skin of HLFC systems, traditionally made from titanium, undergoes a laser micro-perforation process tailored to the material being perforated. If CFRP is to replace titanium, understanding the effect this process has on the thermal properties of the polymer matrix, such as the linear coefficient of thermal expansion (LCTE) and glass transition temperature (Tg), is essential. In this work, various thermal analysis techniques were employed to characterise these properties on samples laser drilled by CAV-Systems. Dynamic mechanical analysis and differential scanning calorimetry were used to determine variances in Tg across perforated and non-perforated samples. Thermomechanical analysis was used to determine the effect of laser processing on the LCTE of CFRP.