Lateral Deflections of Circular Cylinder Walls during Buckling

The lateral deflections of circular cylinders with thin walls were recorded during buckling. Ten pick-up points were chosen along a transverse section of the cylinder, and their deflections recorded simultaneously.

The results suggest, within the precision of the measurements made, that buckling starts simultaneously or with a delay not larger than 0·02 sec, in a large region of the transverse section. Sometimes a local buckling wave appears before general collapse, but this wave does not seem to propagate continuously towards the final shape of the buckled surface.

It can also be concluded that, at buckling and after 0·01 or 0·02 sec, the wall tends directly to a stable polyhedral configuration, with a well-determined number of sides. No intermediate stage could be detected.

These results are interpreted according to previous studies of one of the authors, in such a way that an explanation of the ‘jump’ phenomenon is attempted, without the necessity to pass over Tsien's ‘energy jump’.