Abstract
Joining is a key enabler for a successful application of thermoplastic composites (TPC) in future multi-material systems. To use joining technologies, such as resistance welding for composite-metal joints, auxiliary joining elements (weld inserts) can be integrated into the composite and used as an interface. The authors pursue the approach of embedding metal weld inserts in TPC during compression moulding without fibre damage. The technology is based on the concept of moulding holes by a pin and simultaneously placing the weld insert in the moulded hole. Subsequently, the composite component can be joined with metal structures using conventional spot welding guns. For this purpose, two different types of weld inserts were embedded in glass fibre reinforced polypropylene sheets and then welded to steel sheets. A simulation of the welding process determined suitable welding parameters. The quality of the joints was analysed by microsections before and after the welding process. In addition, the joint strength was evaluated by chisel tests as well as single-lap shear tests for the different weld insert designs. It could be shown that high-quality joints can be achieved by using the innovative technology and that the load-bearing capacity is significantly influenced by the weld inserts head design.
Highlights
Thermoplastic composites (TPC) have an important contribution to modern lightweight construction due to their excellent density-related mechanical properties and established efficient production processes [1]
Microscopic examinations cross sections before were carried out to whether selected process parameters are suitable for manufacturing high-quality joining zones
For the subsequent welding process, suitable process parameters were determined by numeric welding simulations, which were verified by the analysis of etched microsections
Summary
Thermoplastic composites (TPC) have an important contribution to modern lightweight construction due to their excellent density-related mechanical properties and established efficient production processes [1]. One of the obstacles for the use of TPC in multi-material systems is the availability of suitable joining technologies. The use of resistance spot welding for multi-material joints is not directly possible due to different physical properties of dissimilar materials, such as melting temperatures and micro-structural incompatibilities [3]. For this reason, various studies address research regarding the welding of dissimilar materials, such as composites or aluminium to steel
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