FLOW LOCALIZATION IN SHEET SPECIMENS WITH PAIRS OF HOLES

The deformation localization behavior of sheet specimens containing ge ometric perturbations in the form of pairs of through-thickness holes is examined. Both experiments and computational modeling are performed in either uniaxial or equal-biaxial tension in order to examine the e ffect of applied loading path on the far-field strain needed to initia te localized necking in the ligament between the hole pairs, The model s also examine the influence of hole spacing and matrix strain hardeni ng on ligament localization. The far-field strain needed to cause the localization of the ligament is shown to increase as the biaxiality of the loading path increases, the hole spacing increases, and the strai n-hardening exponent increases. The present study also indicates that the onset of localized necking can be predicted by employing the Hill criterion, if the local strain states within the ligament are taken in to account.