Competition between Brittle Fracture and Plastic Collapse in the Failure of Thin Rectangular Panels

Abstract. A centre-cracked panel of elastic-plastic material of unit thickness is loaded remotely by an uniaxial traction acting along its longitudinal axis. Making use of the Dugdale-Barenblatt model, the size ω of the plastic segments ahead of the crack tips is obtained by equilibrium considerations. Connected to ω, a generalised elastic-plastic stress intensity factor K is subsequently defined which, as ω→0, approaches the ordinary elastic one. Once the critical values ωc or Kc at the onset of the unstable propagation of the crack have been specified, the residual-strength curves for plane stress state can be easily deduced. Moreover, conditions are sought for which ductile fracture, brittle fracture or plastic collapse takes place.