The effect of a rotational spring on the global stability aspects of the classical von Mises model under step loading

The present work deals with the global stability aspects of a simple two-de grees-of-freedom autonomous initially imperfect damped model, under step (c onservative) loading. The proposed system is an extension of the classical limit point one firstly introduced by von Mises, with the addition of a lin ear rotational spring. The effect of its properties (stiffness and damping) are fully assessed and under certain combinations of the parameters involv ed a third possibility of postbuckling dynamic response is revealed. This i s associated with a point attractor response on a stable prebuckling fixed point, although dynamic buckling has already occurred, a finding validating new relevant phenomena reported recently in the literature.