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Braunschweig, Germany

Unger C.,Laser Zentrum Hannover e.V. | Schiel M.,Brunswick University of Technology | Dilger K.,Brunswick University of Technology
Welding and Cutting

In recent times, so-called "multi-material structures" have been utilised in vehicle construction to an increasing extent. This inevitably leads to adjustments in the existing fabrication processes using joining technology. Until now, it has been the state of the art to apply the adhesive for structural adhesive-bonded joints already in the body shell, i.e. very early in the process chain, and to cure the mostly one-component structural adhesives while the body shell is passing through the cataphoretic paint drier. If structurally relevant components are to be replaced by fibre-reinforced plastics, these must be joined to the already painted bodywork in the final assembly. If a painted joining member and an unpainted joining member or two painted joining members are to be joined with each other by means of the adhesive bonding technology in this way, there are several different procedures. On the one hand, the regions relevant to the adhesive bonding operation can be masked before the painting. On the other hand, automated paint removal before the adhesive bonding is conceivable. Direct adhesive bonding on the finish-painted surface is imaginable as well. In the case of the first point, it is merely necessary to take account of process sequences with regard to masking and demasking. Therefore, it is not intended to deal with this separately. Within the framework of the project portrayed here, investigations were conducted instead into methods of establishing mechanical properties of the overall joint as well as into processes for removing the paint using different laser beam sources. Source

Esderts A.,Clausthal University of Technology | Wilmes C.,Clausthal University of Technology | Bartout D.,TU Berlin | Stark R.,TU Berlin | And 2 more authors.
Welding and Cutting

The investigations show that it is possible to design joints brazed with little heat in a way appropriate for operation. Not only similar steel joints but also mixed joints consisting of steel and aluminium can be executed by selecting the correct brazing parameters. The selection of a suitable computing concept must be accompanied by the deliberation about what scope of work should be performed. The optimised nominal stress concept with the consideration of the seam geometry and the extended notch stress concept with real seam radii have proven to be suitable. The users now have at their disposal concepts depending on the chosen combination of the joining members and a suitable brazing material. According to the application, it is now possible to carry out designing in a way appropriate for operation. Moreover, it must be borne in mind that all the fabrication influences have already been taken into account by using the componentlike specimens. Source

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