Prediction of Local Strain and Hardness in Sheet Forming

A simulation procedure to predict local deformation and properties in deep drawing and other sheet forming processes has been developed, and model experiments were performed to verify the predicted local strain after various ways and degrees of deformation. A strip of aluminium alloy sheet was pulled through a gap between a die and a punch, and bent around a rounded edge and bent back again. Local strains in a cross section of the sheet were estimated from hardness values measured before and after bending by using the hardness – strain relationship obtained for the alloy from tests carried out in tension and compression and with alternating deformation. The finite element (FE) model using ABAQUS was adjusted to the experimental set-up as closely as possible. The agreement between predictions and experiments is in the range of experimental scatter and the general trends are excellently reproduced. However, the precision of hardness measurements is not high enough to check the reliability of the numerical predictions in detail.