Post-severance analysis of impulsively loaded beams

The dynamic energy imparted to structures can cause material failure. The present investigation considers such a failure for a simply supported beam which is subjected to a blast loading idealised as an initial velocity distributed uniformly throughout the span. The theoretical solutions are developed using a rigid, perfectly plastic idealization and are exact within the context of dynamic plasticity. A simple failure criterion, shown to be derived from Continuum Damage Mechanics, is used in the calculations. Attention is focused on the motion of the beam after it fails and becomes detached from supports. It is shown that a considerable amount of energy remains in the beam after failure, which depends on the beam geometry. Part of this energy is consumed in changing the beam shape after severance, with the remainder as kinetic energy of the beam travelling as a rigid body.

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