Experimental investigation and numerical modelling of spot welding–adhesive joints response

Hybrid joints obtained by a combination of two simple techniques, e.g. by spot welding and adhesive, are relatively modern joints developed especially for application in aerospace industry. This contribution describes the modelling and testing of structural elements by application of an angle bar and spot welding techniques with the introduction of adhesive layers between adherends. Numerical modelling of the mechanical response using the Finite Element Analysis requires a description of 3 different damage processes: (1) plastic degradation of the spot welded points, (2) plastic deterioration of the joined parts around the regions of spot points and (3) degradation of the adhesive layer. The whole uniaxial deformation process of samples was experimentally investigated with the application of 2 Digital Image Correlation systems to monitor the development of deformation up to the final failure. The first damage process starts within the adhesive layer, much below the maximum force that can be carried by the specimen. The second damage process activated in the joined adherends surrounding the spot welded points – near the maximum of the carrying force. The failure of the specimens took place when the adhesive layer was almost totally degraded and the welded spots were subjected to intensive plastic degradation.