An integrated finite element-based simulation framework: From hole piercing to hole expansion

• Developed an integrated FE framework from hole piercing to hole expansion.
• Accurately captured the shear edge burr formation trend in the hole-piercing models.
• Carried Shear edge information after hole-piercing into hole-expansion model.
• The calculated HER in the hole-expansion model correspond well with experiments.

An integrated finite element-based modeling framework is developed to predict the hole expansion ratio (HER) of AA6111-T4 sheet by considering the piercing-induced damages around the hole edge. Using damage models and parameters calibrated from previously reported tensile stretchability studies, the predicted HER correlates well with experimentally measured HER values for different hole piercing clearances. The hole piercing model shows burrs are not generated on the sheared surface for clearances less than 20%, which corresponds well with the experimental data on pierced holes cross-sections. Finite-element-calculated HER also is not especially sensitive to piercing clearances less than this value. However, as clearances increase to 30% and further to 40%, the HER values are predicted to be considerably smaller, also consistent with experimental measurements. Upon validation, the integrated modeling framework is used to examine the effects of different hole piercing and hole expansion conditions on the critical HERs for AA6111-T4.