Pierluigi Fanelli

Analysis of Static Strength and Failure Mode of FSSW Joint in Aluminum Alloy

In this paper an analysis of Friction Stir Spot Welds (FSSW), applied to lap joint aluminum alloy is presented. The analyses regards the structural behavior of FSSW joints in order to assess the failure mode and its dependence on mechanical properties distribution of the sheets material and, consequently, on process parameters.FSSW joint is analyzed by means of a complex 3D FE model, which allows to evaluate, in a parametric manner, the multifaceted internal geometry of the joint and the actual distribution of material mechanical characteristics after welding. Experimental tests allowed to verify the results and to calibrate the material characteristics in the FE model.Copyright

Influence of non-axisymmetric material anisotropy on FSSW static strength

This paper regards the analysis of structural behavior of Friction Stir Spot Welds (FSSW) in order to assess the failure mode and its dependence on mechanical properties distribution of the sheets material and on process parameters. In particular, in this paper is investigated the influence of non-axisymmetric anisotropy of material characteristics on static strengthand failure mode of FSSW. FSSW joint is analyzed by means of a complex 3D Finite Elements model, which allows to evaluate, in a parametric manner, the multifaceted internal geometry of the joint and the actual distribution of material mechanical characteristics after welding. Experimental tests allowed to verify the results and to calibrate the material model in the Finite Elementsanalyses.

Modelling spot welded joints in elastic-plastic field

In this paper two analytical approaches for the evaluation of spot weld joints behavior in elastic plastic conditions are presented and compared. The procedures are based on two new theoretical models of spot weld region: a circular plate, with a central rigid nugget, having two variable thickness profiles. The complex closed-form solutions allow to describe the displacement of a rigid nugget while plasticity and moderately large deflections are present. These approaches allow to reach a reliable spot weld region model which can be used as the basis to develop a spot weld element in FE analysis even when plasticity and large deflections are in effect. The correct evaluation of the spot stiffness is the basis of a reliable evaluation of fatigue resistance or failure mode of the joint and, consequently, allows to correctly simulate the behavior of an actual multi-spot structure.