Loading rig in which axially compressed thin cylindrical shells buckle near theoretical values

Fifteen near-perfect electroformed nickel cylindrical shells of highR/t ratios have been buckled by axial compression using a special loading-rig system. Buckling-stress values averaged 85 percent, and ranged from 80 to 96 percent, of the classical theoretical bucklingstress value. The loading rig described in this report makes use of a simple procedure for accurately aligning the thin shell with the load axis and, also, for maintaining the circularity of the shell at its end by accommodating for slightly different diameters, with the use of tapered circular end caps which provide exact fits in each case. The rig also provides a setup in which shells may be free to twist, tip and translate, or be restrained from these motions. Comparison between restrained and unrestrained tests reveoled no noticeable change in the buckling load. However, with the restraining mechanism, slightly higher postbuckling loads, repeated buckling loads and an increased number of circumferential waves resulted.