Dynamic buckling experiments of fluid-structure-coupled co-axial thin cylinder

The purpose of this paper is to clarify dynamic buckling behaviours such as buckling mode and buckling pressure for thin cylindrical shells immersed i n fluid subjected to seismic excitations. For this purpose, dynamic bucklin g experiments of thin cylindrical shells placed inside a rigid liquid conta iner are carried out using a shaking table. These shells and the container are intended to represent thermal baffles and a main vessel of a fast breed er reactor, respectively. The fluid pressure caused by horizontal excitatio n induces buckling deformation which involves flower-shaped deformation, wh ich is a type of external pressure buckling. The buckling pressure is measu red with Various types of the test cylinders under seismic excitations and this pressure is confirmed to agree with static buckling pressure predicted by static buckling analysis. It is also found that sub-harmonic vibration occurs under a certain sinusoidal excitation inducing a sudden increase in response displacement at a lower pressure level than the buckling pressure under seismic excitations. Based on these experiments, it is pointed out th at, in seismic design, to prevent the buckling of thermal baffles, static b uckling analyses can be used as long as sub-harmonic vibration does not occ ur. (C) 1999 Elsevier Science S.A. All rights reserved.