Article ID: 2025.00138
This study aims to clarify the thermal piercing behavior of carbon fiber reinforced thermoplastics (CFRTP) using near-infrared heating. The objective of the proposed thermal piercing method is to suppress stress concentration and strength reduction around the hole compared with conventional mechanical drilling. The materials used for the experiments were carbon fiber reinforced polypropylene (CF/PP) and carbon fiber reinforced polyether ether ketone (CF/PEEK) laminates. Firstly, heating experiments of the laminates were conducted using near-infrared heating and high-frequency induction heating in order to investigate suitable heating methods for thermal piercing. A ring shaped near-infrared heater was used for infrared heating, and a pancake-shaped coil with 2 MHz high-frequency power source was used for induction heating. The results showed that near-infrared heating enabled uniform heating regardless of the stacking sequence of the laminates. Based on these results, thermal piercing machine consisting of near-infrared ring heater, puncture pin, and servo press unit capable of precisely controlling load and displacement was developed. Various experiments revealed the thermal piercing behavior of each laminate and the associated process issues. Furthermore, the damage behavior around the pierced area was evaluated by double-lap tensile shear tests. It was found that the maximum load and toughness of the thermally pierced specimens were improved compared with those of mechanically drilled specimens.
