Interface surface behaviour in the upsetting of sandwich metal sheets

The expansion of the contact surface is a typical problem in welding by the pressure technique. The present work is concerned with some aspects of the strain state of the metal during the plastic deformation of sandwich sheets. Based upon a theoretical model for the plane-strain upsetting of a two-metal sandwich sheet, the non-plane forming of the interface surface in connection with the fracture of the surface layers is estimated. The results of the model are in good accordance with the results of experiments into the upsetting of aluminium-aluminium aluminium-steel and aluminium-copper sandwich sheets.