Induction heating of UD C/PEKK cross-ply laminates

Abstract

Induction welding is an attractive fusion bonding technology for carbon fiber reinforced thermoplastic composites. The process relies on an alternating magnetic field to induce eddy currents in the composite adherents. The generation of eddy currents is difficult in unidirectionally (UD) reinforced plies, due to their low transverse electrical conductivity. Heating of UD ply-based composites therefore requires contact between plies having a different fiber orientation. Currently, process window definition for UD ply-based composites involves trial-and-error procedures, while moreover, the process is sensitive to small variations in material properties. Improved control of the process requires a proper understanding of the physical mechanisms governing heat generation, while process simulation capabilities are needed for process window development and optimization. This paper studies the influence of lay-up on the induction heating or UD ply-based composites. Two lay-ups were considered, namely a dispersed lay-up of [0/90]3s and a grouped lay-up of [03/903]s. A simulation model was implemented to model the heating process. The required electrical conductivities were obtained experimentally. Validation experiments showed that the model was able to predict the induction heating of the laminate with the dispersed lay-up rather well, while it underpredicted the heating rate of the laminate with the grouped lay-up.