Electrothermal Joining of Carbon‐Fiber Reinforced Polymer Matrix Composites Using Radio‐Frequency Fields

ABSTRACT This study delves into the ability of radio frequency (RF) induction heating to join carbon‐fiber reinforced polymer matrix composites (PMC). Previous works have shown that RF heating can efficiently heat carbon fibers. This study demonstrates that the high heating rates achieved by carbon fibers under RF exposure can be effectively utilized for noncontact heating and curing during the joining of carbon‐fiber‐reinforced PMCs. First, a coil‐based RF induction applicator was designed, and its heating efficiency was both simulated and experimentally evaluated to identify the RF frequency that enables the most efficient heating of carbon‐fiber‐reinforced PMCs. Following this, an RF frequency of ~154 MHz was selected to cure a commercial resin used for joining PMC samples using the designed applicator. The Mode I interlaminar fracture toughness (G _IC ) was then measured for all joined and RF‐cured PMC samples and compared with that of conventionally oven‐cured joints and bulk PMC materials. The RF‐heated joints exhibited an average G _IC value of 0.232 N/mm, comparable to oven‐cured joined samples (0.288 N/mm), and bulk material (0.213 N/mm). Furthermore, statistical analysis of the fracture strength distributions across sample sets indicated that RF‐heated joints are comparable in strength to both oven‐cured joints and the bulk material. These results demonstrate that RF heating can produce PMC joints with mechanical performance similar to conventional oven curing, while offering advantages such as higher heating rates, localized heating, and noncontact processing.