DYNAMIC ELASTIC-PLASTIC BEHAVIOR OF WHIPPING PIPES - EXPERIMENTS AND THEORETICAL-MODEL

This paper is concerned with the problem of pipe whip, the dynamic res ponse of a high pressure piping system subjected to an end force as th e result of a pipe break which releases a jet of fluid from the broken section. Both experimental and theoretical results are presented conc erning the dynamic elastic-plastic behaviour of cantilever pipes subje cted to a transverse force pulse at the free end. Comparisons between experimental data and theoretical predictions are made for mild-steel pipes with outer diameter-to-thickness ratios of 19.5, 28 and 32. It i s demonstrated that, for these geometries, the whipping pipes display three characteristically different responses, viz. elastic, plastic ha rdening behaviour for thick pipes, elastic, plastic hardening-softenin g behaviour for moderately thick pipes and elastic, plastic hardening- softening-collapse behaviour for thinner pipes. The experimental data taken from a series of high speed films are compared with the predicti ons of the instantaneous shapes of the whipping pipes derived from bot h a rigid, perfectly-plastic, large deflection, dynamic beam model and a more comprehensive model which incorporates the effects of elastici ty and plastic hardening and softening, the details of which are prese nted in the paper. Copyright (C) 1996 Elsevier Science Ltd.