Torsional buckling analysis of bellows

Tsukimori, Kazuyuki*; Iwata, Koji; not registered; not registered

PNC has proceeded the feasibility study in respect of the bellows expansion joint for FBR pipings because the expansion point is an effective measure to rationaliz evarious piping systems. Essencially bellows should be designed not to be subjected to torsional loads and usually bellows is protected by hardware not to move in the direction of torsion. Actually, however, there are some sources of torsional deformation, e.g. the clearance of bearing structure, the deformation of hardware etc. Therefore it must be available to limit the torsional displacement of bellows clearly in view of improvement of reliability in design and fabrication. The torsional buckling behavior of bellows was investigated with both theory and numerical analysis. The new element, 3-mode axisy㎜etric shell harmonic series element (NAXSHEL3) which was developed in the FINAS fimite element computer progran, was used for the buckling eigen valve analysis. The numerical solutions corresponded to the theory very well in a wide range of dimensions and number of convolutions. Besed on these results the framework of the design rule related to the torsion of bellows was drawn.