Nonclassical stability problems: Instability of slender tubes under pressure

Several nonclassical stability problems dealing with simple cantilever colu mns of practical engineering importance an comprehensively presented. The s alient feature of these rather peculiar problems is that column instability with a tubular cross section filled with a liquid or subjected to gas pres sure may occur while its cross section remains axially unstressed. Interest ing subcases are also discussed where the static stability criterion of exi stence of two adjacent equilibria fails to predict the actual critical load . This leads to the erroneous conclusion that the undeformed configuration is the only equilibrium position, being stable irrespective of the level of external loading. Hence, the dynamic stability criterion which is of gener al validity must be employed for establishing the critical load. It has als o been clarified that the hydrostatic pressure load, although nonconstant-d irectional, cannot be identified as nonconservative.