Advances in fusion bonding techniques for joining thermoplastic matrix composites: a review

Joining composite materials is an issue because traditional joining technol ogies are not directly transferable to composite structures. Fusion bonding and the use of thermoplastic films as hot melt adhesives offer an alternat ive to mechanical fastening and thermosetting adhesive bonding, Fusion bond ing technology which originated from the thermoplastic polymer industry has gain a new interest with the introduction of thermoplastic matrix composit es (TPC) which are currently regarded as candidates for primary structures. The improvement of thermoplastic polymer matrices, with the introduction o f recent chemistries such as PEEK, PEI and PEKEKK. exhibiting increased mec hanical performance, service temperature and solvent resistance (for the se mi-crystalline systems) also supported the growth of interest for fusion bo nding. This review looks at the state of the art of fusion bonding technolo gy and focuses particularly on the three most promising fusion bonding tech niques: ultrasonic welding, induction welding and resistance welding. Physi cal mechanisms involved in the fusion bonding process for modelling purpose s are discussed including heat transfer, consolidation and crystallinity as pects. Finally, the application of fusion bonding to joining dissimilar mat erials, namely thermosetting composites (TSC)/TPC and metal/TPC joints, is reviewed. (C) 2001 Elsevier Science Ltd. All rights reserved.