Vibration and stability of axially loaded structures: Experimental and numerical studies

In the present paper, the interplay between vibration and stability in axially loaded beams and trusses is analyzed through experimental and numerical studies. Firstly, an experimental research on the fundamental frequency evolution in slender beams subjected to imposed axial displacements is presented. Different geometrical imperfections were analyzed, leading to distinguish two different phases in the fundamental frequency vs. axial load curves. We therefore present a multibody dynamic simulation of these experimental tests, showing a good agreement between numerical and experimental results. Lastly, we present results from finite element modeling of elementary space trusses subjected to a dead load, in terms of natural frequencies vs. load curves. In particular, we investigated the effects of direction and magnitude of the applied force on the natural frequencies and vibration modes of tripod-shaped trusses, comparing different constraint conditions and several geometrical configurations. Results show interesting aspects of the dynamic behavior of axially loaded elements, such as softening vs. stiffening structural responses and particular relationships between natural frequencies and buckling loads