FINITE-ELEMENT MODELING OF HYDRAULIC BULGING DURING SHEET-METAL FORMING

The ABAQUS finite element analysis code has been used to provide a computer simulation of bulging tests performed on the CR1 grade of strip steels. The influence of varying mesh size and element type was examined, together with variations of the normal anisotropy factor for the material. Good correlation was achieved between the predicted and measured data for pressure-bulge height and pressure-polar strain relationships up to the onset of material instability. With regard to through thickness strain at the bulge pole, the overall correlation between predicted and experimental data was good, but improved with strip thickness. The predicted and experimental hoop/radial strain distributions were shown to compare very well at levels of strain preceding the onset of local instability. As the normal anisotropy factor was increased from 1.0 (isotropic) to 1.3 (anisotropic), the strain was distributed more evenly, which implies that higher levels of strain can be achieved before necking and fracture.