“…Schmidt and Winterstetter [27] carried out experimental and numerical investigations on the buckling behaviour of unstiffened cylindrical shells loaded by combined axial compression and torsion. Pal'chevskii [28] showed that the buckling mode of the cylindrical shell under axial compression (number of half-wave in the circumferential direction ππ) depends on the ratios πΏπΏ π
π
β and π
π
π‘π‘ β where πΏπΏ, π
π
and π‘π‘ are the length, radius and thickness of the shell. Cho et al [29] developed an empirical formula to predict the collapse strength of composite cylindrical-shell structures under external pressure loads.…”