Temporal spatial transfer characteristics and cross-scale fusion behavior mechanism of interface temperature in induction welding of plain carbon fiber polyphenylene sulfide

Abstract

The intricate multiphysics coupling conditions and nonlinear characteristics inherent in carbon fiber composite induction welding render the temperature transfer properties of the interface and the fusion connection mechanism across different scales ambiguous. In this study, a transient 3D finite element model was developed to simulate the induction welding process of carbon fiber reinforced polyphenylene sulfide (CF/PPS) composites, utilizing an electromagnetic-thermal multiphysics coupling mechanism. This investigation revealed that the electromagnetic effect leads to the accumulation of magnetic flux and spatial constraints, thereby triggering an eddy current concentration effect at the interface, which serves as an additional influencing factor in induction welding's edge effect. Simultaneously, the temperature distribution at the induction welding interface exhibits a gradient characteristic over both time and space: fluctuations in the current heat source result in a pronounced gradient distribution pattern of 225 %-680 % in welding interface temperature differences, accompanied by a 43.29 % reduction in shear strength. Notably, this study delves into the intricate origin of the induction welding heat source, elucidating that the generation of induced current in the magnetic field by carbon fiber overlap contributes to volumetric heat induction. This facilitates the welding process to some extent, despite the significantly lower heat contribution compared to thermally conductive wire meshes. In conclusion, to gain deeper insights into the impact of heat input on the fusion behavior of the bonding interface, SEM analysis was conducted on the experimental samples to examine the fusion morphology of the induction welding interface. Additionally, the method of EDS elemental analysis has also been used to investigate the generation and fusion mechanisms of welding defects. The amalgamation of numerical simulation technology and multi-scale material characterization serves as a methodological guide for researching the welding mechanisms of composite materials and even extends to investigations within the domain of metal connections. Furthermore, it paves the way for exploring a multidimensional research horizon in the realm of material joining and molding.