Point attractors and dynamic buckling of autonomous systems under step loading

Abstract

In this study the dynamic response of autonomous mainly dissipative multi D.O.F. systems under step loading is re-examined. Based on the geometrical point of view of the theory of non-linear dynamical systems and the rapidly developing theory of attractors, the investigation focuses on limit point like systems, with snapping as their salient feature. It is found that dynamic buckling (through a saddle or its neighborhood) , although leading to a large amplitude motion, may be associated with a point attractor response on the pre-buckling fixed point, depending on the amount of damping considered in close conjunction with the motion channel geometry and the total potential characteristics of all (stable and complementary) equilibria. For such systems, only a straightforward fully non-linear dynamic analysis can provide valid information on the global dynamic stability, since the shape of the total potential hypersurface may become very complicated, rendering energy aspects practically not applicable. A 2-D.O.F. model, simulating an asymmetric suspended roof is comprehensively analyzed to capture the above findings, and a parametric investigation is carried out, revealing a variety of new dynamic response types and leading to a more accurate insight of the stability of motion in the large.