An experimental study of the nonlinear dynamics of cylindrical shells with clamped ends subjected to axial flow

This paper presents experimental results on the nonlinear dynamics and stability characteristics of thin-walled clamped-clamped circular cylindrical shells in contact with flowing fluid. The experiments were conducted with three experimental set-ups: one for experiments with elastomer shells in annular air-flow, the second for elastomer shells with internal air-flow, and the last one for aluminium or plastic cylindrical shells with internal water-flow. In all cases the interaction between the shell and the fully developed flow gives rise to instabilities in the form of static or dynamic divergence at sufficiently high flow velocities. The aim of the experimental study was (i) to gather data on the critical flow velocity for instability and on the post-critical flow/displacement-amplitude relationship, and (ii) to undertake an analysis of the experimental results and to compare them qualitatively with theoretical predictions. The experimental results show a softening type nonlinear behaviour, with a large hysteresis in the velocity for the onset and cessation of divergence.