THEORETICAL-ANALYSIS OF LARGE-DEFORMATION SIMULTANEOUS TEARING AND PEELING OF ELASTOPLASTIC MATERIALS

Simultaneous tearing and peeling of multiple strips is theoretically i nvestigated using the large deflection theory of cantilevers made of e lastoplastic material with linear strain hardening. The relationship b etween the fracture toughness and the curvature at the fracture propag ation front is obtained for general cases. It is shown that for the mo ment loading case, the non-dimensional external moment, m(1), during t earing and peeling along straight paths, is a constant and is independ ent of the initial beam length L(0). With concentrated force loading, the non-dimensional force f will reach a constant value f = f(m) durin g propagation. It is shown that f(m) is almost the same for both initi ally straight and pre-bent beams, and decreases with an increase in th e external force loading angle phi. For initially straight beams, when the non-dimensional fracture toughness, D, is small, f(m) may be less than the initiation force f(i) for fracture. F-m/H does not increase linearly with an increase in the beam width B-0 and decreases at large B-0 after it passes through a peak value. Comparison is made with exp erimental results for the tearing of ductile metal sheets along straig ht paths and the tearing fracture roughness value is found, including a method that uses propagation crack front curvature alone, without ad ditional reference to the tearing force. However, the accuracy of the curvature at the crack propagation front has a large effect on the est imation of fracture toughness. High work-hardening and/or low toughnes s materials have no rapid change of curvature away fi om the crack fro nt so that good estimates are possible and vice versa for low work-har dening solids.