EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Multi material components, also known as hybrid material systems, are of growing interest to industry. The ongoing need for high performance structural and functional components requires that combinations of dissimilar materials are explored in order to develop and efficiently produce products that achieve a balance of appropriate characteristics or new properties at reasonable cost. Besides mechanical or adhesive bonding, ultrasonic welding is a promising technique for joining dissimilar materials.

So far, ultrasonic welding is mostly used in the packaging industry to reliably join polymers cost-effectively, or to join soft non-ferrous metals such as aluminium and copper for electrical applications. Ultrasonic welding of hybrid material systems, such as metal/CFRP joints, has been a focus of research during the last decade. In addition, several multi-metal combinations like aluminium and magnesium, copper, steel or titanium have been ultrasonically welded. Ultrasonic welding of brittle materials, such as glasses and ceramics with metals is challenging and has been investigated, partially using an air beared anvil to ensure homogeneous stress distribution on the joining partners.

In the work presented here, the potential of ultrasonic welding is demonstrated for one functional and one structural hybrid material system, introducing the welding process, mechanical properties and microstructure of the joints.

Tubular metal–FRP hybrids, produced by a novel variant of ultrasonic metal welding, are investigated for the first time as a potential substitute for metallic hydraulic tubes in airplanes. The oscillating welding system moves around the tubular joining partners to generate a sealed high strength orbital connection.

Brittle rare earth permanent magnets were joined to stainless steel for the first time by torsional ultrasonic welding representing a potential magnetic component. A promising shear strength of 35 MPa was achieved, which is significantly higher in comparison to the strength of 20 MPa for adhesively bonded joints.