On the Concept of Stability of Inelastic Systems

Abstract : The various methods of structural analysis are reviewed, and the basic elastic buckling problem of the Euler strut is discussed. Simple models are used to show the important differences between buckling in the plastic range and classical elastic instability. Nonlinear behavior is shown often to be the key to a physically valid solution. The nonconservative nature of plastic deformation alone or in combination with nonlinearity requires concepts not to be found in classical approaches. However, the classical linearized condition of neutral equilibrium is not relevant in inelastic buckling. Analyses of the models suggest that the same information is obtained from essentially static systems by assuming initial geometrical imperfections as by assuming dynamic disturbances. Both approaches are helpful in understanding the physical phenomena.