Analysis and Optimization for Carbon Fiber Reinforced Thermoplastic Induction Welding With Magnetic Flux Concentrator

Induction welding of carbon fiber reinforced thermoplastic (CFRTP) composites has become one of the most promising welding techniques, attributed to its efficiency, adaptability, and noncontact advantages. However, the uneven temperature field within the welding region severely restricts the weld strength. In this paper, a focused induction welding method (FIWM) was proposed, devoted to controlling magnetic field energy and regulating the temperature field. A three-dimensional electro-magnetic-thermal Multiphysics model was developed to analyze temperature distribution, and the model was validated by induction welding experiments. To guide the magnetic field distribution and reduce the temperature gradient, a cylindrical permanent magnet is introduced into FIWM as a magnetic flux concentrator (MFC). The surrogate models for equilibrium temperature, temperature gradient, and effective area were established to rapidly optimize multiple process parameters. Thus, the optimal parameters were found out by the particle swarm optimization (PSO) method. The results show that the temperature gradient decreased from 123.89°C to 49.68°C, and the effective area increased from 41.0 to1900.3 mm². Finally, the strength of the welded joint was assessed by single lap shear tests, and the result showed that the mechanical properties could reach 36.09 ± 1.44 MPa. Therefore, FIWM is an efficient approach to regulate the temperature field and improve the mechanical performance in CFRTP induction welding.