Electromagnetic pulse crimping of form fit joints was investigated using tubes in the aluminium alloy EN AW-6060, with a diameter of 50 mm and a wall thickness of 1,5 mm. First the influence of the charging voltage and the geometrical groove parameters on the deformation behaviour and localised thickness reduction of the tube wall was investigated. The experimental results provided data for optimising the groove design. The Design of Experiments method was used to optimise the shape and dimensions of the internal workpieces with a double groove design. Results of tensile tests on the crimp joints allowed determining the most important parameters for the groove design. Based on these observations an optimal double groove joint design was proposed. The deformation and failure behaviour of the crimp joints during tensile testing were experimentally studied using the digital image correlation technique. This technique was used to measure the local and global deformation of the joint. Failure mechanisms include pull-out, local shearing and fracture of the tube. Three main failure modes were observed.
The electromagnetic pulse process can be an alternative for many conventional production processes. This process variant was investigated, with the emphasis on tubular joints bearing axial tension and/or torsion loading.
Magnetic pulse welding is a new, very innovative but nearly unknown production process. The working principle of the welding process is based on the use of electromagnetic forces to deform and to weld workpieces. Since this sophisticated welding process doesn't use heat to realise the weld, it offers important advantages with regard to the conventional welding techniques!
The workpieces are placed inside a coil. A large amount of energy is compressed and discharged in an extremely short period of time. The high energy flows in the coil, and the discharge of electric energy induces the so-called "eddy currents" in the external workpiece. Both currents (in the coil and in the external workpiece) induce magnetic fields, which oppose each other. The reaction forces between the opposing magnetic fields are forcing the external part towards the internal part at high velocity to cause welding. No protecting atmosphere, filler materials or other aiding materials are necessary. The magnetic pulse welding process is a "cold" welding process, the material does not get warmer than 30°C. Due of this, no heat affected zone is created, and the metal is not degraded. The weld becomes the strongest part of the assembly.
The FATWELD project developed techniques for improving the performance of welded, high-strength steels (yield strengths of 700 and 960 MPa) at thicknesses of 5-20 mm, for use in fatigue-loaded, welded structures, e.g., construction equipment, transportation vehicles and lifting devices.
The MetalMorphosis research project aimed at developing innovating joining processes for composites and metals, based on the electromagnetic pulse technology. This promising technology allows a range of new hybrid metal-composite components to be manufactured, and that matches the current trend towards lightweight materials in the automotive industry. Based on the novel insights acquired, demonstrator parts specifically targeted at the automotive market were developed, namely a hybrid metal-composite brake pedal and shock absorber.
The project CASSTIR (started up at the end of 2006), funded by the Belgian Science Policy, is a collaboration between BWI, UCL, CEWAC and UGent. The project aimed at stimulating and introducing the innovative friction stir welding technique applied to aluminium alloys in Belgium, as well as obtaining a profound knowledge in this welding process by studying the friction stir joint characteristics into great detail.