1. Resistance welding of thermoplastic composites Background Thermosetting and thermoplastic polymers are two kinds of matrix for fibre reinforced polymer (FRP) composites. Compared with thermosetting composites (TSC), thermoplastic composites (TPC) are more environmentally friendly for both manufacturing and recycling processes. Compared with mechanical joining and adhesive bonding techniques, resistance welding has been regarded as a more suitable joining techniques for TPCs, and it has already been applied in the aircraft industry for secondary structures, i.e. the fixed leading edges of A380. In order to apply TPCs for the primary structural components such as fuselage and wings, key technologies related to the manufacturing of TPCs are being developed in the frame of TAPAS project. Therefore, in order to utilize resistance welding for primary TPCs structure, higher level knowledge of the welding mechanisms should be known. Publications -Shi H, Villegas IF, Bersee HEN. Effect of Fibre-Matrix Adhesion and Fibre orientation on Thermoplastic Composite Welded Joints. SAMPE 2013. Long Beach, CA, USA. May 6-9, 2013. -Shi H, Villegas IF, Bersee HEN. An investigation on the strain distribution of resistance welded thermoplastic composite joints. 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Honolulu, Hawaii, USA. Apr 23-26, 2012. -Villegas IF, Shi H, Bersee HEN. Processing Windows For Resistance Welding of Thermoplastic Composites: What Lies Underneath? ECCM 15. Venice, Italy. Jun 24-28, 2012. -Shi H, F.Villegas I, Bersee HEN. Modelling of Heat Transfer and Consolidation for Thermoplastic Composites Resistance Welding. ICCM 18. Jeju, South Korea. Aug 21-26, 2011 Research outline Combining process modelling and experimental tests in the analysis, investigations are performed at levels of material, process and structure. PhD Candidate: Huajie Shi Department: ASM Section: Structural Integrity & Composites Supervisor: I.F. Villegas, H.E.N. Bersee Promoter: M.J.L. van Tooren Start date: 05-10-2009 Funding: CSC, TAPAS project Cooperations: Fokker, Airbus Aerospace Engineering Resistance welding setup (developed in TUD) Objectives The objective of this study is to investigate the mechanisms of the welding and reveal the relationships between material properties, welding process and the welds performance. Schematic drawing of resistance welding setup Source: Fokker Aerostructures, the Netherlands Progress 1: Welding process model Transient heat transfer models are developed for both static resistance welding and continuous resistance welding, based on which welding mechanisms such as consolidation, crystallization and squeezing flow are also looked into. Progress 2: Welds quality characterization In order to assess the quality of the resistance welded structures, reliable testing method should be selected. Therefore, various mechanical testing methods are employed and compared. Progress 3: Process induced voids An investigation on the process induced voids/porosities, i.e. residual volatile induced voids and fibre de-compaction induced voids, is performed. Progress 4: Welds quality optimization In order to improve the mechanical performance of the welds, the effect of heating time, heating element, fibre orientation and fibre-matrix adhesion on the welds quality is studied. Progress 5: Process control A welding quality control strategy for resistance welding process is proposed by detecting and utilizing the weld- thickness evolution.