Advancing Thermoplastic Composite Heating Through Iterative Induction Coil Optimization

Thermoplastics provide several advantages over thermoset composites, including the potential for fastener-free assembly via induction welding. Key parameters in modeling this process include coil frequency, excitation current, and coil offset distance. However, optimizing heat generation through coil geometry remains underexplored. This study aims to derive relationships between coil geometry, heating rate, and frequency through an iterative coil design approach. Two coil design groups are developed to target heat generation in specific regions. Each design undergoes a numerical analysis loop to assess heating performance. Designs showing high heating rates and appropriate temperature profiles are fabricated and experimentally tested. The thermocouple temperature data from these tests are compared to numerical predictions to validate model accuracy. Results show strong agreement between simulations and experiments. The best-performing coils are then used in the induction welding of a stiffened fuselage demonstrator. Welding parameters are determined for each component in the stiffened fuselage demonstrator, and joint performance is evaluated by prying open the welded joints for inspection.