Study of thermoplastic composite joining technology by electromagnetic induction heating

The development of light structures in the transport field is closely related to the development of manufacturing and processing technologies. The thermoplastic matrix composite materials are very interesting also for the possibility of hot forming by deformation, and their use is continually increasing. Moreover, these materials allow the possibility of performing welded joints of the parts. The automotive industry and aerospace industry seem to be the industrial sectors that have the most significant potential for application of thermoplastic composite materials. The joining of thermoplastic composites could be carried out using hot melt adhesives or with fusion welding of the thermoplastic matrix. The heating of a hot melt adhesive, or the thermoplastic matrix could be carried out with electromagnetic induction technology. This PhD thesis deals with the electromagnetic induction heating of thermoplastic matrix composite materials for adhesive bonding, and also study for the first time the influence of the current frequency on the heat penetration depth. A numerical model was developed using two different Multiphysics Software, such as Jmag and COMSOL; then the models were validated using an experimental campaign. The main original result of the work is that in the case of thermoplastic matrix composites, the higher the current frequency the higher is the depth of the heat penetration, unlike the case of the metal alloys.