Colloquia

Summary

Carbon-reinforced thermoplastic composites are increasingly used in the aerospace industry due to their lightweight and recyclable properties. Thermoplastic composites allow for fusion bonding (welding) and have key benefits over traditional thermoset composites that require lengthy curing processes and cannot be remelted. However, while significant research has been done on welding techniques, little attention has been given to disassembling these welded joints, a crucial process for  maintenance, repair, and recycling in the aerospace industry. This thesis focuses on the disassembly of thermoplastic composites, called de-welding. De-welding is the reverse of the welding process, and involves reheating the joint interface and applying forces to separate the bonded parts with minimal damage.

This thesis focused on resistance heating as the preferred method, as it directly heats the joint interface, reducing the heat-affected zone to avoid damaging of the composite adherends.  The main objective of  this research was to assess the feasibility of de-welding TPCs using resistance  heating, specifically with carbon fiber-reinforced Low Melting Poly-Aryl-Ether-Ketone (CF/LMPEAK). The feasibility was evaluated through both numerical modeling and experimental tests on two geometries: coupon-sized specimens and larger structural elements. For the latter, an experimental test bench was developed.

The results of the coupon-sized specimens showed that dewelding via resistance heating is a feasible method for lowering the dissambly force. When applied to larger structural elements, de-welding proved successful in achieving low disassembly force, no de-consolidation, and an intact heating element. These outcomes were obtained by the application of a heat sink, insulator layer and relatively short processing time. This thesis took the first step in de-welding by resistance heating, and more research is required to develop this disassembly technique into a mature manufacturing process in the aviation industry.