Failure of plastic structures under intense dynamic loading: modes, criteria and thresholds

This paper surveys the failure modes, criteria and thresholds of plastic st ructural members (beams, rings, plates and thin shells, etc.) subjected to intense dynamic loads, such as impulsive velocities or impact. Besides the three basic failure modes identified by Menkes and Opat [7] for impulsively loaded beams, namely, large inelastic deformation (Mode I), tensile tearin g (Mode II) and transverse shear failure at the supports (Mode III), more c omplicated failure behaviours observed in the cases of complex structural m embers and/or dynamic loading conditions are summarized and discussed. All the failure criteria used in the relevant theoretical analyses including el ementary failure criterion, energy density criterion and quasi-static equiv alent energy criterion, etc., are commented upon. The threshold impulsive v elocities for the onset of Mode III failure of fully clamped beams predicte d from various approaches are compared with each other, as well as with the relevant experimental results. Particular attention is paid to structural members with macro imperfections (for example, containing cracks or notches ), where failure which usually originate from the imperfections are fractur e-dominant so that local fracture criteria, such as the J-integral criterio n, should be incorporated into the global structural failure description. I n addition, some most recent results of the authors' studies are briefly pr esented. (C) 2000 Elsevier Science Ltd. All rights reserved.