Issue 45

G. Giuliano et alii, Frattura ed Integrità Strutturale, 45 (2018) 164-172; DOI: 10.3221/IGF-ESIS.45.14 171 respectively. In Fig. 13, the force-displacement curves of the punch, obtained by means of 2D finite element analysis for a coefficient of friction of 0.05, 0.1 and 0.2, is presented until the instability condition (FLP=1) occurs. Figs. 12 and 13 show that the stroke tended to increase under conditions both of instability (FEM) and fracture (experimental) by improving the lubrication conditions. Figure 11 : Comparison between the force-stroke curves of the punch, obtained by FEM for FLP = 1, under perfect lubrication conditions, using both shell (3D) and axisymmetric elements (2D). The described comparison makes it possible to validate, in the practice of designing a plastic deformation process, the use of the criterion, introduced in the 3D and 2D FEM code, which establishes the occurrence of instability conditions in the sheet to be deformed. Figure 12 : Comparison between the force-displacement curves of the punch, obtained experimentally for different friction conditions until the sheet fracture occurring. C ONCLUSIONS he aim of the work was the development of a calculation model useful for checking the feasibility of forming sheet metal components, using the formability limit curve. The behavior of the AA6060 alloy was evaluated in terms of mechanical strength, with the description of the flow stress curve and the FLC. The model was based on the finite element simulation of the sheet metal forming process using the commercial software MSC.Marc. In a first phase, the results from the 3D and 2D FEM modeling were compared. Subsequently, the 2D model was used, under different friction conditions, to verify the feasibility of a simple axisymmetric vessel. T