Bifurcation of a shaft under magnetic load

The paper is concerned with the effect of coexistence of self- and external excitations of slender rotating shafts. A symmetric edge movement is assum ed to excite a simply supported and geometrically nonlinear shaft. The anal ysis is focused on the resonant behaviour for both stable and unstable stat ic equilibrium. Computer simulation is applied to the equations of motion w ith special attention paid to periodic amplitude behaviour and irregular sh aft motions for various excitation frequencies.