DYNAMIC EFFECTS IN MECHANICAL STRUCTURES WITH GAPS AND IMPACTING - ORDER AND CHAOS

The paper discusses orderly and chaotic dynamic responses of simple me chanical structures with clearances and impacting. Experimental result s from a simulator of a rotating machine with one loose pedestal are p resented, and a summary of analytical results for this case is given. The orderly and chaotic responses obtained through numerical integrati on are presented in the form of bifurcation diagrams. The second part of the paper discusses an existence of the main and higher order reson ances in structures with clearances and impacting, which are excited b y external periodic forces. For a one-degree-of-freedom nonlinear syst em, the application of a discontinuous variable transformation, follow ed by an averaging method provides analytical formulae describing the system response amplitudes and phases in the proximity of the main and harmonic resonances. A numerical example illustrates the results. The discussed methodology can be generalized for the cases of more comple x systems.