CONCERTINA TEARING OF METAL PLATES

Small scale experiments on wedge indentation into metal plates reveale d the existence of two different failure modes. In the case of sharp w edges with a small tip angle, plates failed by developing a longitudin al cut at or ahead of the rip of the wedge followed by the formation o f two curls at the wake of the wedge. However, the same plates failed by folding in front of the wedge and tearing at remote boundaries when the wedge was blunt and/or the tip angle was large. This so-called '' concertina tearing'' mode was also observed in intermediate scale labo ratory tests and in real-world grounding accidents. The present paper develops a simplified theory of the process of concertina tearing. Clo sed-form solutions are derived for the plate-resisting force and the l ength of the folding wave. The results were compared with small and in termediate scale indentation tests on metal plates, and showed good ag reement.