EXPERIMENTAL AND THEORETICAL STUDIES ON BUCKLING OF CONICAL AND CYLINDRICAL SHELLS UNDER COMBINED LOADING

Abstract

Abstract : Results of an experimental program on the instability of unstiffened aluminum-alloy conical shells under combinations of 3 loadings, axial compression, torsion and external or internal pressure are presented and compared with linear theory. Improvements in experimental technique permitted many repeated buckling tests on the same metal specimen without noticeable damage and yielded reliable interaction curves. Some tests on Mylar conical shells under similar combined loading, are then discussed. Tests of the mechanical properties of Mylar A sheets revealed considerable anisotropy that casts some doubt on the reliability of results obtained with Mylar specimens. The general instability of stiffened cylindrical shells under combined axial compression and external or internal pressure is then discussed and design implications are considered. The variation of stiffener spacing in stiffened conical shells yields an improvement in structural efficiency. Optimization studies that investigate this improvement for ring stiffened cones in detail are presented. Results of a continuation of an experimental program on the general instability of ring-stiffened conical shells are presented. Tests on integrally machined steel specimens under torsion, axial compression and combined torsion and axial compression are discussed and compared with theory.