Yield criterion for a perforated sheet with a uniform triangular pattern of round holes and a low ligament ratio

The plastic behavior of a perforated sheet with round holes in a triangular pattern depends largely on the hole size of the perforated sheet. This study investigates the plastic behavior of perforated sheets with low ligament ratios. A yield criterion for the perforated sheets is also proposed in terms of apparent stresses by employing the equivalent-continuum approach. The effectiveness of the proposed yield criterion is then demonstrated by comparing the predicted values of apparent yield stresses and apparent strain ratios with results obtained from finite-element analysis and experiment.