CORRELATION BETWEEN VIBRATIONS AND BUCKLING OF STIFFENED CYLINDRICAL SHELLS UNDER EXTERNAL PRESSURE AND COMBINED LOADING

摘要

A vibration correlation technique for definition of the boundary conditions of stringer-stiffened shells, developed earlier for axial compression loading, is extended to the case of external pressure and axial compression. The technique consists essentially of an experimental determination of the natural frequencies, in vibration modes that resemble the buckling modes of a loaded shell, and assessment of the equivalent elastic restraints which represent the boundary conditions by comparison within theoretically predicted frequencies. With these assessed restraints obtained from non¬destructive tests, the buckling pressures or loads are calculated.