Dynamic stability of two harmonically excited thin-walled structures carrying a top mass

In this paper the dynamic stability of two imperfect thin-walled structures is investigated both theoretically and experimentally. The first structure is a vertical, slender beam carrying a top mass and the second structure is a cylindrical shell also carrying a top mass. In both cases, the top mass can only move in vertical direction; the top mass weight does not cause static buckling. However, both the beam and the cylindrical shell are also harmonically excited at their base in vertical (i.e. axial) direction. In both structures, for certain dynamic excitation set-points, this will induce dynamic buckling. The numerical results are obtained using a semi-analytical approach, enabling accurate as well as fast parameter studies. Shaker and amplifier dynamics are included in both models. New insights in the steady-state behavior of both structures are obtained. Good quantitative (beam) and qualititative (cylinder) correspondence between numerical and experimental results is found