Failure behavior in electrically-assisted mechanical clinching joints

The failure behavior of AA6061-T6/DP590 clinched joints was investigated using an integrated 2-step FE model. The effectiveness of the electro-plastic effect on the formability and the material flow was studied on aluminum to high-strength steel hybrid clinched joints. An electrical-thermo-mechanical FE model was developed to predict the failure behavior during the tensile shear testing of the joints. Different fracture criteria were applied including Brozzo, normalized Cockroft-Latham, and Rice-Tracey. A new method is proposed to calibrate the abovementioned criteria based on the experimentally determined fracture displacement. The results indicated that the clinched joints made by electrically-assisted mechanical clinching were 46% stronger than those made by conventional mechanical clinching. This was due to increased formability provided by the electro-plastic effect. The numerical model involving the Brozzo fracture criterion showed the highest accuracy. Indeed, the athermal effect of the electro-plasticity led to a hybrid neck fracture mode.