ON THE PRESSURE BUCKLING OF RECTANGULAR BELLOWS FOR FUSION-REACTORS

Bellows are planned for use in the torus vacuum vessel of ITER to abso rb the relative displacements resulting from thermal expansion. Though both sides of the bellows are in vacuum during normal conditions, the se bellows would be subjected to external or internal pressures of sev eral MPa during accidents. Since the vacuum vessel forms the tritium b oundary during postulated accidents, the prevention of bellow failure in these events is very important in the ITER design. For equipping th e internal components, rectangular bellows are preferable to circular bellows in the ITER design. However, investigations concerning pressur e buckling of rectangular bellows are few. Therefore, we investigated the buckling behavior of rectangular bellows and proposed a simplified evaluation method based on the half pitch model for bellows with a re latively high length-to-diameter ratio, where elastic column squirm is dominant. For bellows with a lower number of convolutions, however, i nplane squirm buckling should be considered, therefore, we have invest igated inplane squirm of rectangular bellows and compared it with that of circular bellows in this paper. (C) 1998 Elsevier Science S.A. All rights reserved.