Some considerations in axisymmetric folding of metallic round tubes

A mathematical analysis is presented for axial crushing of round tubes in concertina mode, wherein the change in thickness along the fold length during its formation, and difference in the yield stress values in compression and tension have been incorporated. The model considers straight folds and the variation of circumferential strain during the formation of a fold. The size of fold, folding parameter (proportions of inside and outside fold lengths) and mean as well as variation of crushing load have been computed. The results thus obtained have been compared with experiments and reasonably good agreement has been observed. The results are of help in understanding the phenomenon of the actual fold formation.