Experimental study of the mechanical strength and the failure of multi-sheet, multi-material spot-welded assemblies under pure and combined loading conditions

Rim Chtourou (1) , Fahmi Chaari (1) , Grégory Haugou (1) , Nicolas Leconte (1, 2) , Eric Markiewicz (1) , Bassem Zouari (3, 4)

1 LAMIH - Laboratoire d'Automatique, de Mécanique et d'Informatique industrielles et Humaines - UMR 8201
2 INSA Hauts-De-France - INSA Institut National des Sciences Appliquées Hauts-de-France
3 ENIS - École Nationale d'Ingénieurs de Sfax | National School of Engineers of Sfax
4 Université de Sfax - University of Sfax

Resistance Spot Welding (RSW) is widely used in the automotive industry thanks to its production convenience and cost effectiveness. Around four thousands spot welds are indeed employed to assemble the body-in-white. RSW of multiple sheets and combining multiple materials are increasingly realized. The Ultra-High-Strength Steels (UHSS) are particularly well suited for the entire range of structural parts requiring good crash resistance. However, the mechanical strength and the rupture of such new generation of RSW under multi-axial loadings is not yet well studied. The present work investigates the mechanical strength and the failure of a three-sheet spot welded assembly composed of two sheets of UHSS 22MnB5 and a third sheet of mild steel DX54D. An advanced experimental procedure is proposed for testing this assembly in pure and combined (tensile shear modes) modes I/II. Two types of specimen with different sheet thicknesses have been studied. The obtained results are analyzed to investigate the loading angle effect and the assembly configuration effect on the mechanical strength. Failure modes are also studied in relation with the increasing of the loading angle. Finally, the parameters of a macroscopic force-based failure criterion dedicated for FE crash modeling are identified.

Domaines: Matériaux et structures en mécanique [physics.class-ph]

Rim Chtourou, Fahmi Chaari, Grégory Haugou, Nicolas Leconte, Eric Markiewicz, et al.. Experimental study of the mechanical strength and the failure of multi-sheet, multi-material spot-welded assemblies under pure and combined loading conditions. 12th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading (DYMAT 2018), Sep 2018, Arcachon, France. pp.02009, ⟨10.1051/epjconf/201818302009⟩. ⟨hal-03433309⟩