INTERACTION BETWEEN REFLECTED ELASTIC FLEXURAL WAVES AND A PLASTIC HINGE IN THE DYNAMIC-RESPONSE OF PULSE LOADED BEAMS

By employing an elastic-perfectly plastic ideal sandwich beam model an d solving the governing equations expressed in finite-difference form, the interaction between the reflected elastic flexural wave and the p lastic hinge in the dynamic response of the beam to a suddenly applied force pulse is examined, The evolution of the plastically deforming r egion in the beam (the plastic hinge) is shown to be closely related t o its encounter with reflected elastic waves. The correlation between the formation of a reversed hinge at the root with the notable oscilla tion in the position of the travelling hinge is also revealed. When th e Seam is loaded by a step force, the plastic hinge locates at a posit ion close to that predicted by the rigid-plastic analysis and it is re latively stable during its interaction with the reflected elastic wave s. When a rectangular pulse is applied, whether the reflected elastic waves can terminate the plastic flow in the plastic zone (i.e, whether the entire plastic zone undergoes complete elastic unloading) is show n to depend on the total impulse imparted to the beam. (C) 1997 Elsevi er Science Ltd.